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Schaeffel F, Swiatczak B. Mechanisms of emmetropization and what might go wrong in myopia. Vision Res 2024; 220:108402. [PMID: 38705024 DOI: 10.1016/j.visres.2024.108402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 03/25/2024] [Accepted: 03/25/2024] [Indexed: 05/07/2024]
Abstract
Studies in animal models and humans have shown that refractive state is optimized during postnatal development by a closed-loop negative feedback system that uses retinal image defocus as an error signal, a mechanism called emmetropization. The sensor to detect defocus and its sign resides in the retina itself. The retina and/or the retinal pigment epithelium (RPE) presumably releases biochemical messengers to change choroidal thickness and modulate the growth rates of the underlying sclera. A central question arises: if emmetropization operates as a closed-loop system, why does it not stop myopia development? Recent experiments in young human subjects have shown that (1) the emmetropic retina can perfectly distinguish between real positive defocus and simulated defocus, and trigger transient axial eye shortening or elongation, respectively. (2) Strikingly, the myopic retina has reduced ability to inhibit eye growth when positive defocus is imposed. (3) The bi-directional response of the emmetropic retina is elicited with low spatial frequency information below 8 cyc/deg, which makes it unlikely that optical higher-order aberrations play a role. (4) The retinal mechanism for the detection of the sign of defocus involves a comparison of defocus blur in the blue (S-cone) and red end of the spectrum (L + M-cones) but, again, the myopic retina is not responsive, at least not in short-term experiments. This suggests that it cannot fully trigger the inhibitory arm of the emmetropization feedback loop. As a result, with an open feedback loop, myopia development becomes "open-loop".
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Affiliation(s)
- Frank Schaeffel
- Myopia Research Group, Institute of Molecular and Clinical Ophthalmology Basel (IOB), Switzerland; Section Neurobiology of the Eye, Institute of Ophthalmic Research, University of Tübingen, Germany; Zeiss Vision Lab, Institute of Ophthalmic Research, University of Tübingen, Germany.
| | - Barbara Swiatczak
- Myopia Research Group, Institute of Molecular and Clinical Ophthalmology Basel (IOB), Switzerland
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2
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Liang C, Li F, Gu C, Xie L, Yan W, Wang X, Shi R, Linghu S, Liu T. Metabolomic profiling of ocular tissues in rabbit myopia: Uncovering differential metabolites and pathways. Exp Eye Res 2024; 240:109796. [PMID: 38244883 DOI: 10.1016/j.exer.2024.109796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/09/2024] [Accepted: 01/16/2024] [Indexed: 01/22/2024]
Abstract
To investigate the metabolic difference among tissue layers of the rabbits' eye during the development of myopia using metabolomic techniques and explore any metabolic links or cascades within the ocular wall. Ultra Performance Liquid Chromatography - Mass Spectrometry (UPLC-MS) was utilized for untargeted metabolite screening (UMS) to identify the significant differential metabolites produced between myopia (MY) and control (CT) (horizontal). Subsequently, we compared those key metabolites among tissues (Sclera, Choroid, Retina) of MY for distribution and variation (longitudinal). A total of 6285 metabolites were detected in the three tissues. The differential metabolites were screened and the metabolic pathways of these metabolites in each myopic tissue were labeled, including tryptophan and its metabolites, pyruvate, taurine, caffeine metabolites, as well as neurotransmitters like glutamate and dopamine. Our study suggests that multiple metabolic pathways or different metabolites under the same pathway, might act on different parts of the eyeball and contribute to the occurrence and development of myopia by affecting the energy supply to the ocular tissues, preventing antioxidant stress, affecting scleral collagen synthesis, and regulating various neurotransmitters mutually.
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Affiliation(s)
- Chengpeng Liang
- Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, 563000, Guizhou Province, China.
| | - Fayuan Li
- Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, 563000, Guizhou Province, China
| | - Chengqi Gu
- Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, 563000, Guizhou Province, China
| | - Ling Xie
- Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, 563000, Guizhou Province, China
| | - Wen Yan
- Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, 563000, Guizhou Province, China
| | - Xiaoye Wang
- Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, 563000, Guizhou Province, China
| | - Rong Shi
- Department of Ophthalmology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563000, Guizhou Province, China
| | - Shaorong Linghu
- Department of Ophthalmology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563000, Guizhou Province, China
| | - Taixiang Liu
- Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, 563000, Guizhou Province, China; Department of Ophthalmology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563000, Guizhou Province, China.
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3
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Chen CS, Lin CF, Chou YL, Lee DY, Tien PT, Wang YC, Chang CY, Lin ES, Chen JJ, Wu MY, Ku H, Gan D, Chang YM, Lin HJ, Wan L. Acupuncture modulates development of myopia by reducing NLRP3 inflammasome activation via the dopamine-D1R signaling pathway. Acupunct Med 2023; 41:364-375. [PMID: 37211683 DOI: 10.1177/09645284231170886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
BACKGROUND Dopamine has been suggested to be a stop signal for eye growth and affects the development of myopia. Acupuncture is known to increase dopamine secretion and is widely used to treat myopia clinically. OBJECTIVE The aim of this study was to determine if acupuncture inhibits myopia progression in form deprived Syrian hamsters by inducing rises in dopamine content that in turn suppress inflammasome activation. METHODS Acupuncture was applied at LI4 and Taiyang every other day for 21 days. The levels of molecules associated with the dopamine signaling pathway, inflammatory signaling pathway and inflammasome activation were determined. A dopamine agonist (apomorphine) was used to evaluate if activation of the dopaminergic signaling pathway suppresses myopia progression by inhibiting inflammasome activation in primary retinal pigment epithelial (RPE) cells. A dopamine receptor 1 (D1R) inhibitor (SCH39166) was also administered to the hamsters. RESULTS Acupuncture inhibited myopia development by increasing dopamine levels and activating the D1R signaling pathway. Furthermore, we also demonstrated that nucleotide-binding oligomerization domain (NOD)-, leucine-rich repeat (LRR)- and pyrin domain-containing protein 3 (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome activation was inhibited by activation of the D1R signaling pathway. CONCLUSION Our findings suggest that acupuncture inhibits myopia development by suppressing inflammation, which is initiated by activation of the dopamine-D1R signaling pathway.
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Affiliation(s)
- Chih-Sheng Chen
- Department of Food Nutrition and Health Biotechnology, Asia University, Taichung
- Division of Chinese Medicine, Asia University Hospital, Taichung
| | - Chi-Fong Lin
- PhD Program for Health Science and Industry, China Medical University, Taichung
| | - Yung-Lan Chou
- School of Chinese Medicine, China Medical University, Taichung
| | - Der-Yen Lee
- Graduate Institute of Integrated Medicine, China Medical University, Taichung
| | - Peng-Tai Tien
- Eye Center, China Medical University Hospital, Taichung
| | - Yao-Chien Wang
- Department of Emergency Medicine, Taichung Tzu Chi Hospital, Taichung
| | - Ching-Yao Chang
- Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung
| | - En-Shyh Lin
- Department of Beauty Science, National Taichung University of Science and Technology, Taichung
| | | | - Ming-Yen Wu
- Eye Center, China Medical University Hospital, Taichung
| | - Hsiangyu Ku
- Department of Ophthalmology and Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
| | - Dekang Gan
- Department of Ophthalmology and Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
| | - Yung-Ming Chang
- The School of Chinese Medicine for Post Baccalaureate, I-Shou University, Kaohsiung
- Department of Chinese Medicine, 1PT Biotechnology Co., Ltd., Taichung
| | - Hui-Ju Lin
- School of Chinese Medicine, China Medical University, Taichung
- Graduate Institute of Integrated Medicine, China Medical University, Taichung
| | - Lei Wan
- School of Chinese Medicine, China Medical University, Taichung
- Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung
- Department of Obstetrics and Gynecology, China Medical University Hospital, Taichung
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Cui Z, Huang Y, Chen X, Chen T, Hou X, Yu N, Li Y, Qiu J, Chen P, Yu K, Zhuang J. Identification of miR-671-5p and Its Related Pathways as General Mechanisms of Both Form-Deprivation and Lens-Induced Myopia in Mice. Curr Issues Mol Biol 2023; 45:2060-2072. [PMID: 36975502 PMCID: PMC10047131 DOI: 10.3390/cimb45030132] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/15/2023] [Accepted: 03/01/2023] [Indexed: 03/06/2023] Open
Abstract
Animal models have been indispensable in shaping the understanding of myopia mechanisms, with form-deprivation myopia (FDM) and lens-induced myopia (LIM) being the most utilized. Similar pathological outcomes suggest that these two models are under the control of shared mechanisms. miRNAs play an important role in pathological development. Herein, based on two miRNA datasets (GSE131831 and GSE84220), we aimed to reveal the general miRNA changes involved in myopia development. After a comparison of the differentially expressed miRNAs, miR-671-5p was identified as the common downregulated miRNA in the retina. miR-671-5p is highly conserved and related to 40.78% of the target genes of all downregulated miRNAs. Moreover, 584 target genes of miR-671-5p are related to myopia, from which we further identified 8 hub genes. Pathway analysis showed that these hub genes are enriched in visual learning and extra-nuclear estrogen signaling. Furthermore, two of the hub genes are also targeted by atropine, which strongly supports a key role of miR-671-5p in myopic development. Finally, Tead1 was identified as a possible upstream regulator of miR-671-5p in myopia development. Overall, our study identified the general regulatory role of miR-671-5p in myopia as well as its upstream and downstream mechanisms and provided novel treatment targets, which might inspire future studies.
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Affiliation(s)
- Zedu Cui
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Yuke Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Xi Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Taiwei Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Xiangtao Hou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Na Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Yan Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Jin Qiu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Pei Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Keming Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
- Correspondence: (K.Y.); (J.Z.); Tel.: +86-20-6667-8735 (J.Z.); Fax: +86-20-8733-3271 (J.Z.)
| | - Jing Zhuang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
- Correspondence: (K.Y.); (J.Z.); Tel.: +86-20-6667-8735 (J.Z.); Fax: +86-20-8733-3271 (J.Z.)
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5
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Rozema J, Dankert S, Iribarren R. Emmetropization and nonmyopic eye growth. Surv Ophthalmol 2023:S0039-6257(23)00037-1. [PMID: 36796457 DOI: 10.1016/j.survophthal.2023.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 02/02/2023] [Accepted: 02/06/2023] [Indexed: 02/16/2023]
Abstract
Most eyes start with a hypermetropic refractive error at birth, but the growth rates of the ocular components, guided by visual cues, will slow in such a way that this refractive error decreases during the first 2 years of life. Once reaching its target, the eye enters a period of stable refractive error as it continues to grow by balancing the loss in corneal and lens power with the axial elongation. Although these basic ideas were first proposed over a century ago by Straub, the exact details on the controlling mechanism and the growth process remained elusive. Thanks to the observations collected in the last 40 years in both animals and humans, we are now beginning to get an understanding how environmental and behavioral factors stabilize or disrupt ocular growth. We survey these efforts to present what is currently known regarding the regulation of ocular growth rates.
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Affiliation(s)
- Jos Rozema
- Visual Optics Lab Antwerp (VOLANTIS), Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium; Institute for Medical Informatics, Statistics, and Epidemiology (IMISE), Leipzig University, Leipzig, Germany.
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6
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Neumann A, Breher K, Wahl S. Effects of screen-based retinal light stimulation measured with a novel contrast sensitivity test. PLoS One 2021; 16:e0254877. [PMID: 34324537 PMCID: PMC8320929 DOI: 10.1371/journal.pone.0254877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 07/05/2021] [Indexed: 02/02/2023] Open
Abstract
Myopia is increasing worldwide hence it exists a pressing demand to find effective myopia control strategies. Previous studies have shown that light, spectral composition, spatial frequencies, and contrasts play a critical role in refractive development. The effects of light on multiple retinal processes include growth regulation, but also visual performance and perception. Changes in subjective visual performance can be examined by contrast sensitivity (CS). This study was conducted to investigate whether retinal light stimulation of different wavelength ranges is able to elicit changes in CS and, therefore, may be used for myopia control purposes. In total, 30 right eyes were stimulated with the light of different wavelength ranges, including dominant wavelengths of ∼480 nm, ∼530 nm, ∼630 nm and polychromatic light via a commercial liquid crystal display (LCD) screen. Stimulation was performed screen full-field and on the optic nerve head only. CS was measured before any stimulation and after each stimulation condition using a novel and time-efficient CS test. Post-stimulation CS changes were analyzed by ANOVA regarding the influencing factors spatial frequency, stimulation wavelength and stimulation location. A priorly conducted verification study on a subset of five participants compared the newly developed CS test to a validated CS test. The novel CS test exhibited good reliability of 0.94 logCS and repeatability of 0.13 logCS with a duration of 92 sec ± 17 sec. No clinically critical change between pre- and post-stimulation CS was detected (all p>0.05). However, the results showed that post-stimulation CS differed significantly at 18 cpd after stimulation with polychromatic light from short-wavelength light (p<0.0001). Location of illumination (screen full-field vs. optic nerve head) or any interactions with other factors did not reveal significant influences (all p>0.05). To summarize, a novel CS test measures the relationship between retinal light stimulation and CS. However, using retinal illumination via LCD screens to increase CS is inconclusive.
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Affiliation(s)
- Antonia Neumann
- Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Katharina Breher
- Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
- Carl Zeiss Vision International GmbH, Aalen, Germany
| | - Siegfried Wahl
- Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
- Carl Zeiss Vision International GmbH, Aalen, Germany
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7
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Thomson K, Karouta C, Ashby R. Form-Deprivation and Lens-Induced Myopia Are Similarly Affected by Pharmacological Manipulation of the Dopaminergic System in Chicks. Invest Ophthalmol Vis Sci 2021; 61:4. [PMID: 33016984 PMCID: PMC7545069 DOI: 10.1167/iovs.61.12.4] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose Animal models have demonstrated a link between decreases in retinal dopamine levels and the development of form-deprivation myopia (FDM). However, the consistency of dopamine's role in the other major form of experimental myopia, that of lens-induced myopia (LIM), is less clear, raising the question as to what extent dopamine plays a role in human myopia. Therefore, to better define the role of dopamine in both forms of experimental myopia, we examined how consistent the protection afforded by dopamine and the dopamine agonist 6-amino-5,6,7,8-tetrahydronaphthalene-2,3-diol hydrobromide (ADTN) is between FDM and LIM. Methods Intravitreal injections of dopamine (0.002, 0.015, 0.150, 1.500 µmol) or ADTN (0.001, 0.010, 0.100, 1.000 µmol) were administered daily to chicks developing FDM or LIM. Axial length and refraction were measured following 4 days of treatment. To determine the receptor subtype by which dopamine and ADTN inhibit FDM and LIM, both compounds were coadministered with either the dopamine D2-like antagonist spiperone (0.005 µmol) or the D1-like antagonist SCH-23390 (0.005 µmol). Results Intravitreal administration of dopamine or ADTN inhibited the development of FDM (ED50 = 0.003 µmol and ED50 = 0.011 µmol, respectively) and LIM (ED50 = 0.002 µmol and ED50 = 0.010 µmol, respectively) in a dose-dependent manner, with a similar degree of protection observed in both paradigms (P = 0.471 and P = 0.969, respectively). Coadministration with spiperone, but not SCH-23390, inhibited the protective effects of dopamine and ADTN against the development of both FDM (P = 0.214 and P = 0.138, respectively) and LIM (P = 0.116 and P = 0.100, respectively). Conclusions pharmacological targeting of the retinal dopamine system inhibits FDM and LIM in a similar dose-dependent manner through a D2-like mechanism.
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Affiliation(s)
- Kate Thomson
- Centre for Research in Therapeutic Solutions, Faculty of Science and Technology, University of Canberra, Canberra, Australia
| | - Cindy Karouta
- Centre for Research in Therapeutic Solutions, Faculty of Science and Technology, University of Canberra, Canberra, Australia
| | - Regan Ashby
- Centre for Research in Therapeutic Solutions, Faculty of Science and Technology, University of Canberra, Canberra, Australia.,Research School of Biology, Australian National University, Canberra, Australia
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8
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Jonas JB, Ang M, Cho P, Guggenheim JA, He MG, Jong M, Logan NS, Liu M, Morgan I, Ohno-Matsui K, Pärssinen O, Resnikoff S, Sankaridurg P, Saw SM, Smith EL, Tan DTH, Walline JJ, Wildsoet CF, Wu PC, Zhu X, Wolffsohn JS. IMI Prevention of Myopia and Its Progression. Invest Ophthalmol Vis Sci 2021; 62:6. [PMID: 33909032 PMCID: PMC8083117 DOI: 10.1167/iovs.62.5.6] [Citation(s) in RCA: 138] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The prevalence of myopia has markedly increased in East and Southeast Asia, and pathologic consequences of myopia, including myopic maculopathy and high myopia-associated optic neuropathy, are now some of the most common causes of irreversible blindness. Hence, strategies are warranted to reduce the prevalence of myopia and the progression to high myopia because this is the main modifiable risk factor for pathologic myopia. On the basis of published population-based and interventional studies, an important strategy to reduce the development of myopia is encouraging schoolchildren to spend more time outdoors. As compared with other measures, spending more time outdoors is the safest strategy and aligns with other existing health initiatives, such as obesity prevention, by promoting a healthier lifestyle for children and adolescents. Useful clinical measures to reduce or slow the progression of myopia include the daily application of low-dose atropine eye drops, in concentrations ranging between 0.01% and 0.05%, despite the side effects of a slightly reduced amplitude of accommodation, slight mydriasis, and risk of an allergic reaction; multifocal spectacle design; contact lenses that have power profiles that produce peripheral myopic defocus; and orthokeratology using corneal gas-permeable contact lenses that are designed to flatten the central cornea, leading to midperipheral steeping and peripheral myopic defocus, during overnight wear to eliminate daytime myopia. The risk-to-benefit ratio needs to be weighed up for the individual on the basis of their age, health, and lifestyle. The measures listed above are not mutually exclusive and are beginning to be examined in combination.
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Affiliation(s)
- Jost B Jonas
- Department of Ophthalmology, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Marcus Ang
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,Department of Ophthalmology and Visual Science, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Pauline Cho
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Jeremy A Guggenheim
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Ming Guang He
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Centre, Sun Yatsen University, Guangzhou, China.,Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
| | - Monica Jong
- Brien Holden Vision Institute, Sydney, Australia.,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.,Discipline of Optometry and Vision Science, University of Canberra, Australia
| | - Nicola S Logan
- School of Optometry, Aston University, Birmingham, United Kingdom
| | - Maria Liu
- School of Optometry, University of California, Berkeley, Berkeley, California, United States
| | - Ian Morgan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Centre, Sun Yatsen University, Guangzhou, China.,Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Kyoko Ohno-Matsui
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, Tokyo, Japan
| | - Olavi Pärssinen
- Department of Ophthalmology, Central Hospital of Central Finland, Jyväskylä, Finland.,Gerontology Research Center and Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Serge Resnikoff
- Brien Holden Vision Institute, Sydney, Australia.,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Padmaja Sankaridurg
- Brien Holden Vision Institute, Sydney, Australia.,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Seang-Mei Saw
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.,Eye & Retina Surgeons, Singapore, Singapore.,Duke-NUS Medical School, Singapore
| | - Earl L Smith
- Brien Holden Vision Institute, Sydney, Australia.,College of Optometry, University of Houston, Houston, Texas, United States
| | - Donald T H Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.,Department of Ophthalmology and Visual Science, Duke-NUS Graduate Medical School, Singapore, Singapore.,Eye & Retina Surgeons, Singapore, Singapore
| | - Jeffrey J Walline
- The Ohio State University College of Optometry, Columbus, Ohio, United States
| | - Christine F Wildsoet
- School of Optometry, University of California, Berkeley, Berkeley, California, United States
| | - Pei-Chang Wu
- Department of Ophthalmology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Xiaoying Zhu
- Biological and Vision Sciences, State University of New York, College of Optometry, New York, New York, United States
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9
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Morgan IG. The biological basis of myopic refractive error. Clin Exp Optom 2021; 86:276-88. [PMID: 14558849 DOI: 10.1111/j.1444-0938.2003.tb03123.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2003] [Revised: 08/04/2003] [Accepted: 09/02/2003] [Indexed: 11/28/2022] Open
Abstract
Myopia is among the most common refractive errors and is associated with the greatest risk of pathological outcomes. Most animals, including humans, are born with hyperopic errors. During development, axial elongation of the eye occurs and is regulated through a vision-dependent process, known as emmetropisation The extremely rapid changes in the prevalence of myopia and the dependence of myopia on the level of education indicate that there are very strong environmental impacts on the development of myopia. This conflicts with the common occurrence of familial patterns of inheritance of myopia, which suggests a role for genetic determination. There are more than 150 defined genetic syndromes in which familial high myopia is one of the features, including some that are not associated with other syndromes. The evidence for the roles of both nature and nurture in the aetiology of myopia is discussed. This review also examines the experimentally induced refractive errors associated with form-deprivation, recovery from form deprivation and the effects of both negative and positive lenses. In addition, it looks at the local and optical control of eye growth. Finally, the various control pathways for growth are considered. These include dopamine, ZENK-glucagon, retinoic acid and retinoic acid receptors, crystallin, seratonin and melatonin, vasoactive intestinal peptide and enkephalins, nitric oxide and various growth factors.
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Affiliation(s)
- Ian G Morgan
- Visual Sciences Group, Research School of Biological Science and Centre for VIsual Science, Australian National University, GPO Box 475, Canberra, ACT, 2601, Australia
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10
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Muralidharan AR, Lança C, Biswas S, Barathi VA, Wan Yu Shermaine L, Seang-Mei S, Milea D, Najjar RP. Light and myopia: from epidemiological studies to neurobiological mechanisms. Ther Adv Ophthalmol 2021; 13:25158414211059246. [PMID: 34988370 PMCID: PMC8721425 DOI: 10.1177/25158414211059246] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 10/25/2021] [Indexed: 12/22/2022] Open
Abstract
Myopia is far beyond its inconvenience and represents a true, highly prevalent, sight-threatening ocular condition, especially in Asia. Without adequate interventions, the current epidemic of myopia is projected to affect 50% of the world population by 2050, becoming the leading cause of irreversible blindness. Although blurred vision, the predominant symptom of myopia, can be improved by contact lenses, glasses or refractive surgery, corrected myopia, particularly high myopia, still carries the risk of secondary blinding complications such as glaucoma, myopic maculopathy and retinal detachment, prompting the need for prevention. Epidemiological studies have reported an association between outdoor time and myopia prevention in children. The protective effect of time spent outdoors could be due to the unique characteristics (intensity, spectral distribution, temporal pattern, etc.) of sunlight that are lacking in artificial lighting. Concomitantly, studies in animal models have highlighted the efficacy of light and its components in delaying or even stopping the development of myopia and endeavoured to elucidate possible mechanisms involved in this process. In this narrative review, we (1) summarize the current knowledge concerning light modulation of ocular growth and refractive error development based on studies in human and animal models, (2) summarize potential neurobiological mechanisms involved in the effects of light on ocular growth and emmetropization and (3) highlight a potential pathway for the translational development of noninvasive light-therapy strategies for myopia prevention in children.
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Affiliation(s)
| | | | | | | | | | | | - Dan Milea
- Singapore Eye Research Institute, Singapore
| | - Raymond P Najjar
- Visual Neurosciences Group, Singapore Eye Research Institute, The Academia, 20 College Road, Discovery Tower Level 6, Singapore 169856
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11
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Ostrin LA, Read SA, Vincent SJ, Collins MJ. Sleep in Myopic and Non-Myopic Children. Transl Vis Sci Technol 2020; 9:22. [PMID: 32879778 PMCID: PMC7442863 DOI: 10.1167/tvst.9.9.22] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 06/07/2020] [Indexed: 12/16/2022] Open
Abstract
Purpose To examine differences in sleep between myopic and non-myopic children. Methods Objective measurements of sleep, light exposure, and physical activity were collected from 91 children, aged 10 to 15 years, for two 14-day periods approximately 6 months apart. Sleep parameters were analyzed with respect to refractive error, season, day of the week, age, and sex. Results Myopic children exhibited differences in sleep duration by day of the week (P < 0.001) and season (P = 0.007). Additionally, myopic children exhibited shorter sleep latency than non-myopic children (P = 0.04). For all children, wake time was later (P < 0.001) and sleep duration was longer (P = 0.03) during the cooler season compared with the warmer season. On weekends, children went to bed later (P < 0.001), woke up later (P < 0.001), and had increased sleep duration (P < 0.001) than on weekdays. Younger children exhibited earlier bedtime (P = 0.005) and wake time (P = 0.01) than older children. Time spent outdoors was positively associated with sleep duration (P = 0.03), and daily physical activity was negatively associated with wake time (P < 0.001). Conclusions Myopic children tended to have more variable sleep duration and shorter latency than non-myopic children. Sleep patterns were influenced by season, day of the week, age, time outdoors, and activity. Translational Relevance Myopic children tended to have more variable sleep duration and shorter latency than non-myopic children, which may reflect previously reported differences in environmental and behavioral factors between refractive error groups.
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Affiliation(s)
- Lisa A Ostrin
- College of Optometry, University of Houston, Houston, TX, USA
| | - Scott A Read
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Brisbane, Queensland, Australia
| | - Stephen J Vincent
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Brisbane, Queensland, Australia
| | - Michael J Collins
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Brisbane, Queensland, Australia
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12
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Levodopa inhibits the development of lens-induced myopia in chicks. Sci Rep 2020; 10:13242. [PMID: 32764736 PMCID: PMC7413395 DOI: 10.1038/s41598-020-70271-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/23/2020] [Indexed: 11/18/2022] Open
Abstract
Animal models have demonstrated a link between dysregulation of the retinal dopamine system and the development of myopia (short-sightedness). We have previously demonstrated that topical application of levodopa in chicks can inhibit the development of form-deprivation myopia (FDM) in a dose-dependent manner. Here, we examine whether this same protection is observed in lens-induced myopia (LIM), and whether levodopa’s protection against FDM and LIM occurs through a dopamine D1- or D2-like receptor mechanism. To do this, levodopa was first administered daily as an intravitreal injection or topical eye drop, at one of four ascending doses, to chicks developing LIM. Levodopa’s mechanism of action was then examined by co-administration of levodopa injections with D1-like (SCH-23390) or D2-like (spiperone) dopamine antagonists in chicks developing FDM or LIM. For both experiments, levodopa’s effectiveness was examined by measuring axial length and refraction after 4 days of treatment. Levodopa inhibited the development of LIM in a dose-dependent manner similar to its inhibition of FDM when administered via intravitreal injections or topical eye drops. In both FDM and LIM, levodopa injections remained protective against myopia when co-administered with SCH-23390, but not spiperone, indicating that levodopa elicits its protection through a dopamine D2-like receptor mechanism in both paradigms.
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13
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Chakraborty R, Ostrin LA, Benavente-Perez A, Verkicharla PK. Optical mechanisms regulating emmetropisation and refractive errors: evidence from animal models. Clin Exp Optom 2019; 103:55-67. [PMID: 31742789 DOI: 10.1111/cxo.12991] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/24/2019] [Accepted: 09/25/2019] [Indexed: 12/22/2022] Open
Abstract
Our current understanding of emmetropisation and myopia development has evolved from decades of work in various animal models, including chicks, non-human primates, tree shrews, guinea pigs, and mice. Extensive research on optical, biochemical, and environmental mechanisms contributing to refractive error development in animal models has provided insights into eye growth in humans. Importantly, animal models have taught us that eye growth is locally controlled within the eye, and can be influenced by the visual environment. This review will focus on information gained from animal studies regarding the role of optical mechanisms in guiding eye growth, and how these investigations have inspired studies in humans. We will first discuss how researchers came to understand that emmetropisation is guided by visual feedback, and how this can be manipulated by form-deprivation and lens-induced defocus to induce refractive errors in animal models. We will then discuss various aspects of accommodation that have been implicated in refractive error development, including accommodative microfluctuations and accommodative lag. Next, the impact of higher order aberrations and peripheral defocus will be discussed. Lastly, recent evidence suggesting that the spectral and temporal properties of light influence eye growth, and how this might be leveraged to treat myopia in children, will be presented. Taken together, these findings from animal models have significantly advanced our knowledge about the optical mechanisms contributing to eye growth in humans, and will continue to contribute to the development of novel and effective treatment options for slowing myopia progression in children.
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Affiliation(s)
- Ranjay Chakraborty
- College of Nursing and Health Sciences, Optometry and Vision Science, Flinders University, Adelaide, Australia
| | - Lisa A Ostrin
- University of Houston College of Optometry, Houston, Texas, USA
| | | | - Pavan Kumar Verkicharla
- Myopia Research Lab, Prof. Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India
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14
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Liu H, Schaeffel F, Trier K, Feldkaemper M. Effects of 7-Methylxanthine on Deprivation Myopia and Retinal Dopamine Release in Chickens. Ophthalmic Res 2019; 63:347-357. [PMID: 31533122 DOI: 10.1159/000502529] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 08/06/2019] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Intake of 7-methylxanthine (7-MX), an adenosine receptor (AR) antagonist, has been shown to inhibit school myopia in children and deprivation myopia in rhesus monkeys, but the underlying mechanisms are not known. Also retinal dopamine seems to be involved in the control of eye growth, and in the brain, ARs and dopamine receptors interact widely by heteromerization. We have studied whether 7-MX can inhibit deprivation myopia also in chickens and whether inhibition may involve the retinal dopamine system. METHODS 7-MX was applied by either tube-feeding (100 µg/g body weight, twice a day) or intravitreal injection (12.5 µg, every other day). Forty-eight 2-week-old chicks wore unilateral diffusers and were randomly assigned to either the tube-feeding group (involving 7-MX, vehicle [xanthan gum], or no feeding, for 13 days) or the intravitreal injection group (involving 7-MX, vehicle, or DMSO, for 8 days). Refractions (REs), ocular biometry (AL, VCD), and scleral and choroidal thickness (ChT) were measured before and after treatment. Dopamine and dihydroxyphenylacetic acid (DOPAC) content were determined in retina and vitreous by HPLC at the end of the experiments. RESULTS No matter how 7-MX was applied, it did not inhibit deprivation myopia in chicks. No significant differences were observed in RE, VCD, AL, and scleral fibrous layer thickness. Feeding 7-MX produced more choroidal thinning in the open contralateral eye compared to control eyes in the vehicle-fed group (-40 ± 14 vs. -1 ± 7 µm, unpaired t test, p < 0.05). DOPAC and dopamine concentration in vitreous and DOPAC concentration in retina did not change with 7-MX. Vitreal dopamine content was significantly decreased in deprived eyes in the groups fed with the vehicle xanthan gum (paired t test, p < 0.01) but not in 7-MX-treated eyes, perhaps indicating a small effect of 7-MX on dopamine. CONCLUSIONS In our study, 7-MX had no effect on DM in chicks and only minor effects on ChT and retinal dopamine. It remains unclear whether 7-MX inhibits myopia through a retinal mechanism or whether it acts directly on choroid and sclera. In the latter case, the finding that myopia is suppressed in mammals but not birds might be explained by differences in scleral structure.
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Affiliation(s)
- Hong Liu
- Aier School of Ophthalmology, Central South University, Changsha, China
- Institute for Ophthalmic Research, Section of Neurobiology of the Eye, University of Tuebingen, Tuebingen, Germany
| | - Frank Schaeffel
- Institute for Ophthalmic Research, Section of Neurobiology of the Eye, University of Tuebingen, Tuebingen, Germany
| | - Klaus Trier
- Trier Research Laboratories, Hellerup, Denmark
| | - Marita Feldkaemper
- Institute for Ophthalmic Research, Section of Neurobiology of the Eye, University of Tuebingen, Tuebingen, Germany,
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Vutipongsatorn K, Yokoi T, Ohno-Matsui K. Current and emerging pharmaceutical interventions for myopia. Br J Ophthalmol 2019; 103:1539-1548. [DOI: 10.1136/bjophthalmol-2018-313798] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 04/22/2019] [Accepted: 04/27/2019] [Indexed: 01/09/2023]
Abstract
Myopia is a major cause of visual impairment. Its prevalence is growing steadily, especially in East Asia. Despite the immense disease and economic burden, there are currently no Food and Drug Administration-approved drugs for myopia. This review aims to summarise pharmaceutical interventions of myopia at clinical and preclinical stages in the last decade and discuss challenges for preclinical myopia drugs to progress to clinical trials. Atropine and oral 7-methylxanthine are shown to reduce myopia progression in human studies. The former has been extensively studied and is arguably the most successful medication. However, it has side effects and trials on low-dose atropine are ongoing. Other pharmaceutical agents being investigated at a clinical trial level include ketorolac tromethamine, oral riboflavin and BHVI2 (an experimental drug). Since the pathophysiology of myopia is not fully elucidated, numerous drugs have been tested at the preclinical stage and can be broadly categorised based on the proposed mechanisms of myopisation, namely antimuscarinic, dopaminergic, anti-inflammatory and more. However, several agents were injected intravitreally or subconjunctivally, hindering their progress to human trials. Furthermore, with atropine being the most successful medication available, future preclinical interventions should be studied in combination with atropine to optimise the treatment of myopia.
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16
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Rucker F. Monochromatic and white light and the regulation of eye growth. Exp Eye Res 2019; 184:172-182. [PMID: 31018118 DOI: 10.1016/j.exer.2019.04.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/02/2019] [Accepted: 04/16/2019] [Indexed: 12/25/2022]
Abstract
Experiments employing monochromatic light have been used to investigate the role of longitudinal chromatic aberration (LCA) as possible signals for emmetropization for many years. LCA arising from the dispersion of light, causes differences in the focal length at different wavelengths and can impose defocus (wavelength defocus). Short-wavelength light focuses with a shorter focal length than long-wavelength light and, as such, would be expected to produce a smaller, more hyperopic eye. Emmetropization can respond to wavelength defocus since animals reared in monochromatic light adjust their refractive state relative to that measured in white light. In many species, animals reared in monochromatic light respond as predicted by wavelength defocus, becoming more hyperopic in blue light and more myopic in red light. However, tree shrews and rhesus monkey become more hyperopic in red light, and while tree shrews initially become more hyperopic in blue light, they later become more myopic. This review examines the experiments performed in monochromatic light and highlights the potential differences in protocols affecting the results, including experiment duration, circadian rhythm stimulation, light intensity, bandwidth, humoral factors and temporal sensitivity.
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Affiliation(s)
- Frances Rucker
- New England College of Optometry, 424 Beacon St, Boston, MA, 02115, USA.
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17
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Troilo D, Smith EL, Nickla DL, Ashby R, Tkatchenko AV, Ostrin LA, Gawne TJ, Pardue MT, Summers JA, Kee CS, Schroedl F, Wahl S, Jones L. IMI - Report on Experimental Models of Emmetropization and Myopia. Invest Ophthalmol Vis Sci 2019; 60:M31-M88. [PMID: 30817827 PMCID: PMC6738517 DOI: 10.1167/iovs.18-25967] [Citation(s) in RCA: 221] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 10/20/2018] [Indexed: 11/24/2022] Open
Abstract
The results of many studies in a variety of species have significantly advanced our understanding of the role of visual experience and the mechanisms of postnatal eye growth, and the development of myopia. This paper surveys and reviews the major contributions that experimental studies using animal models have made to our thinking about emmetropization and development of myopia. These studies established important concepts informing our knowledge of the visual regulation of eye growth and refractive development and have transformed treatment strategies for myopia. Several major findings have come from studies of experimental animal models. These include the eye's ability to detect the sign of retinal defocus and undergo compensatory growth, the local retinal control of eye growth, regulatory changes in choroidal thickness, and the identification of components in the biochemistry of eye growth leading to the characterization of signal cascades regulating eye growth and refractive state. Several of these findings provided the proofs of concepts that form the scientific basis of new and effective clinical treatments for controlling myopia progression in humans. Experimental animal models continue to provide new insights into the cellular and molecular mechanisms of eye growth control, including the identification of potential new targets for drug development and future treatments needed to stem the increasing prevalence of myopia and the vision-threatening conditions associated with this disease.
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Affiliation(s)
- David Troilo
- SUNY College of Optometry, State University of New York, New York, New York, United States
| | - Earl L. Smith
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Debora L. Nickla
- Biomedical Sciences and Disease, New England College of Optometry, Boston, Massachusetts, United States
| | - Regan Ashby
- Health Research Institute, University of Canberra, Canberra, Australia
| | - Andrei V. Tkatchenko
- Department of Ophthalmology, Department of Pathology and Cell Biology, Columbia University, New York, New York, United States
| | - Lisa A. Ostrin
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Timothy J. Gawne
- School of Optometry, University of Alabama Birmingham, Birmingham, Alabama, United States
| | - Machelle T. Pardue
- Biomedical Engineering, Georgia Tech College of Engineering, Atlanta, Georgia, United States31
| | - Jody A. Summers
- College of Medicine, University of Oklahoma, Oklahoma City, Oklahoma, United States
| | - Chea-su Kee
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, SAR, China
| | - Falk Schroedl
- Departments of Ophthalmology and Anatomy, Paracelsus Medical University, Salzburg, Austria
| | - Siegfried Wahl
- Institute for Ophthalmic Research, University of Tuebingen, Zeiss Vision Science Laboratory, Tuebingen, Germany
| | - Lyndon Jones
- CORE, School of Optometry and Vision Science, University of Waterloo, Ontario, Canada
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18
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Ostrin LA. The ipRGC-driven pupil response with light exposure and refractive error in children. Ophthalmic Physiol Opt 2018; 38:503-515. [PMID: 30259538 DOI: 10.1111/opo.12583] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 09/08/2018] [Indexed: 11/30/2022]
Abstract
PURPOSE The intrinsically photosensitive retinal ganglion cells (ipRGCs) signal environmental light, control pupil size and entrain circadian rhythm. There is speculation that ipRGCs may be involved in the protective effects of light exposure in myopia. Here, the ipRGC-driven pupil response was evaluated in children and examined with light exposure and refractive error. METHODS Children ages 5-15 years participated. Subjects wore an actigraph device prior to the lab visit for objective measures of light exposure and sleep. For pupillometry, the left eye was dilated and presented with stimuli, and the consensual pupil response was measured in the right eye. Pupil measurements were preceded by 5 min dark adaptation. In Experiment 1 (n = 14), 1 s long wavelength light ('red,' 651 nm, 167 cd m-2 ) and 10 increasing intensities of 1 s short wavelength light ('blue,' 456 nm, 0.167-167 cd m-2 ) were presented with a 60 s interstimulus interval. A piecewise two-segment regression was fit to the stimulus response function to determine the functional melanopsin threshold. Pupil responses were analysed with light exposure over the previous 24 h. For Experiment 2 (n = 42), three 1 s red and three 1 s blue alternating stimuli were presented with a 60 s interstimulus interval. Following an additional 5-min dark adaption, the experiment was repeated. Pupil metrics included peak constriction, the 6 s and 30 s post-illumination response (PIPR), early and late area under the curve (AUC). Following pupil measurements, cycloplegic refractive error and axial length were measured. RESULTS For Experiment 1, PIPR metrics demonstrated a graded response to increasing intensity blue stimuli, with a mean functional melanopsin threshold of 6.2 ± 4.5 cd m-2 (range: 0.84-16.7 cd m-2 ). The 6 s PIPR and early AUC were associated with 24-h light exposure for high intensity stimuli (33.3 and 83.3 cd m-2 , p < 0.005 for both). For Experiment 2, there were no associations between pupil metrics and refractive error. The 6 s PIPR and early AUC to blue stimuli were significantly increased for Trial 2 compared to Trial 1. CONCLUSIONS The ipRGC-driven pupil responses in children were robust and similar to responses previously measured in an adult population. The 6 s PIPR and early AUC to high intensity blue stimuli were associated with previous light exposure. There were no associations between the ipRGC-driven pupil response and refractive status in this cohort.
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Affiliation(s)
- Lisa A Ostrin
- College of Optometry, University of Houston, Houston, USA
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Wang M, Schaeffel F, Jiang B, Feldkaemper M. Effects of Light of Different Spectral Composition on Refractive Development and Retinal Dopamine in Chicks. ACTA ACUST UNITED AC 2018; 59:4413-4424. [DOI: 10.1167/iovs.18-23880] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Min Wang
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Tuebingen, Germany
- The Second Xiangya Hospital, Central South University, Xiangya, Hunan Province, China
| | - Frank Schaeffel
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Tuebingen, Germany
| | - Bing Jiang
- The Second Xiangya Hospital, Central South University, Xiangya, Hunan Province, China
| | - Marita Feldkaemper
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Tuebingen, Germany
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20
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Chakraborty R, Ostrin LA, Nickla DL, Iuvone PM, Pardue MT, Stone RA. Circadian rhythms, refractive development, and myopia. Ophthalmic Physiol Opt 2018; 38:217-245. [PMID: 29691928 PMCID: PMC6038122 DOI: 10.1111/opo.12453] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/11/2018] [Indexed: 12/14/2022]
Abstract
PURPOSE Despite extensive research, mechanisms regulating postnatal eye growth and those responsible for ametropias are poorly understood. With the marked recent increases in myopia prevalence, robust and biologically-based clinical therapies to normalize refractive development in childhood are needed. Here, we review classic and contemporary literature about how circadian biology might provide clues to develop a framework to improve the understanding of myopia etiology, and possibly lead to rational approaches to ameliorate refractive errors developing in children. RECENT FINDINGS Increasing evidence implicates diurnal and circadian rhythms in eye growth and refractive error development. In both humans and animals, ocular length and other anatomical and physiological features of the eye undergo diurnal oscillations. Systemically, such rhythms are primarily generated by the 'master clock' in the surpachiasmatic nucleus, which receives input from the intrinsically photosensitive retinal ganglion cells (ipRGCs) through the activation of the photopigment melanopsin. The retina also has an endogenous circadian clock. In laboratory animals developing experimental myopia, oscillations of ocular parameters are perturbed. Retinal signaling is now believed to influence refractive development; dopamine, an important neurotransmitter found in the retina, not only entrains intrinsic retinal rhythms to the light:dark cycle, but it also modulates refractive development. Circadian clocks comprise a transcription/translation feedback control mechanism utilizing so-called clock genes that have now been associated with experimental ametropias. Contemporary clinical research is also reviving ideas first proposed in the nineteenth century that light exposures might impact refraction in children. As a result, properties of ambient lighting are being investigated in refractive development. In other areas of medical science, circadian dysregulation is now thought to impact many non-ocular disorders, likely because the patterns of modern artificial lighting exert adverse physiological effects on circadian pacemakers. How, or if, such modern light exposures and circadian dysregulation contribute to refractive development is not known. SUMMARY The premise of this review is that circadian biology could be a productive area worthy of increased investigation, which might lead to the improved understanding of refractive development and improved therapeutic interventions.
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Affiliation(s)
- Ranjay Chakraborty
- College of Nursing and Health Sciences, Flinders University, Adelaide, Australia
| | | | | | | | - Machelle T. Pardue
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur
| | - Richard A. Stone
- University of Pennsylvania School of Medicine, Philadelphia, USA
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Yang X, Huang G, Xu MJ, Zhang C, Cheng Y, Yang Z. Cloning and functional characterization of the DA2 receptor gene in Chinese mitten crab (Eriocheir sinensis). PLoS One 2018; 13:e0193999. [PMID: 29554147 PMCID: PMC5858782 DOI: 10.1371/journal.pone.0193999] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 02/22/2018] [Indexed: 12/27/2022] Open
Abstract
Dopamine (DA) plays a modulatory role in numerous physiological processes such as light adaptation and food intake, and exerts these functions through DA receptors (DARs). This study presents, for the first time, isolation and characterization of the dopamine receptor 2(DA2 receptor) cDNA from the intestinal tissue of Eriocheir sinensis, an economically important freshwater aquaculture species in China. The DA2 receptor cDNA sequence, which was obtained by rapid amplification of cDNA ends, is 2369bp long, encode peptide of 589 amino acid, and is highly homologous to related sequences in crustaceans. Analysis of the deduced amino acid sequence and the structure of the DA2 indicated that this receptor is a member of the family of G protein-coupled receptors (GPCRs), as it contains seven transmembrane domains and other common signatures of GPCRs. RT-PCR showed that the expression of the DA2 receptor gene was distributed in various tissues, and high expression levels were observed in the cranial ganglia and the thoracic ganglia. Further study of the effect of photoperiod on DA2 expression showed that constant darkness induced a significant increase in DA2 expression in the cranial ganglia. Finally, analysis of DA2 receptor expression under different feeding statuses showed that there was significantly greater expression in the hepatopancreas and intestines after feeding than before feeding, but there were no differences in expression between the before feeding and during feeding periods in either tissue. Our results indicate that the DA2 receptor structurally belongs to the family of G protein-coupled receptors, and that the cranial ganglia are the main tissues in which the DA2 receptor participates in light adaptation during dark hours. In addition, the DA2 receptor in E. sinensis may be involved in the physiological regulation of the hepatopancreas and digestive tract after the ingestion of food. This study provides a foundation for further exploration of the light adaptation and digestive functions of the DA2 receptor in decapods.
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Affiliation(s)
- Xiaozhen Yang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture; Shanghai Ocean University, Shanghai, China
| | - Genyong Huang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture; Shanghai Ocean University, Shanghai, China
| | - Min-jie Xu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture; Shanghai Ocean University, Shanghai, China
| | - Cong Zhang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture; Shanghai Ocean University, Shanghai, China
| | - Yongxu Cheng
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture; Shanghai Ocean University, Shanghai, China
- * E-mail:
| | - Zhigang Yang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture; Shanghai Ocean University, Shanghai, China
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Li B, Luo X, Li T, Zheng C, Ji S, Ma Y, Zhang S, Zhou X. Effects of Constant Flickering Light on Refractive Status, 5-HT and 5-HT2A Receptor in Guinea Pigs. PLoS One 2016; 11:e0167902. [PMID: 27959948 PMCID: PMC5154534 DOI: 10.1371/journal.pone.0167902] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 11/22/2016] [Indexed: 11/18/2022] Open
Abstract
Purpose To investigate the effects of constant flickering light on refractive development, the role of serotonin (i.e.5-hydroxytryptamine, 5-HT)and 5-HT2A receptor in myopia induced by flickering light in guinea pigs. Methods Forty-five guinea pigs were randomly divided into three groups: control, form deprivation myopia (FDM) and flickering light induced myopia (FLM) groups(n = 15 for each group). The right eyes of the FDM group were covered with semitransparent hemispherical plastic shells serving as eye diffusers. Guinea pigs in FLM group were raised with illumination of a duty cycle of 50% at a flash frequency of 0.5Hz. The refractive status, axial length (AL), corneal radius of curvature(CRC) were measured by streak retinoscope, A-scan ultrasonography and keratometer, respectively. Ultramicroscopy images were taken by electron microscopy. The concentrations of 5-HTin the retina, vitreous body and retinal pigment epithelium (RPE) were assessed by high performance liquid chromatography, the retinal 5-HT2A receptor expression was evaluated by immunohistofluorescence and western blot. Results The refraction of FDM and FLM eyes became myopic from some time point (the 4th week and the 6th week, respectively) in the course of the experiment, which was indicated by significantly decreased refraction and longer AL when compared with the controls (p<0.05). The concentrations of 5-HT in the retina, vitreous body and RPE of FDM and FLM eyes were significantly increased in comparison with those of control eyes (both p<0.05). Similar to FDM eyes, the expression of retinal 5-HT2A receptor in FLM eyes was significantly up-regulated compared to that of control eyes (both p<0.05). Western blot analysis showed that retinal 5-HT2A receptor level elevated less in the FLM eyes than that in the FDM eyes. Moreover, the levels of norepinephrine and epinephrine in FDM and FLM groups generally decreased when compared with control groups (all p<0.05). Conclusions Constant flickering light could cause progressive myopia in guinea pigs. 5-HT and 5-HT2A receptor increased both in form deprivation myopia and flickering light induced myopia, indicating that 5-HT possibly involved in myopic development via binding to5-HT2A receptor.
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Affiliation(s)
- Bing Li
- Central Laboratory, Jinshan Hospital affiliated to Fudan University, Shanghai, China
| | - Xiumei Luo
- Department of Ophthalmology, Jinshan Hospital affiliated to Fudan University, Shanghai, China
| | - Tao Li
- Department of Ophthalmology, Jinshan Hospital affiliated to Fudan University, Shanghai, China
| | - Changyue Zheng
- Department of Ophthalmology, Jinshan Hospital affiliated to Fudan University, Shanghai, China
| | - Shunmei Ji
- Department of Ophthalmology, Jinshan Hospital affiliated to Fudan University, Shanghai, China
| | - Yuanyuan Ma
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Shuangshuang Zhang
- Department of Dermatology, Jinshan Hospital affiliated to Fudan University, Shanghai, China
| | - Xiaodong Zhou
- Department of Ophthalmology, Jinshan Hospital affiliated to Fudan University, Shanghai, China
- * E-mail:
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Dillingham CM, Guggenheim JA, Erichsen JT. The effect of unilateral disruption of the centrifugal visual system on normal eye development in chicks raised under constant light conditions. Brain Struct Funct 2016; 222:1315-1330. [PMID: 27535408 PMCID: PMC5368197 DOI: 10.1007/s00429-016-1279-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 07/22/2016] [Indexed: 12/02/2022]
Abstract
The centrifugal visual system (CVS) comprises a visually driven isthmic feedback projection to the retina. While its function has remained elusive, we have previously shown that, under otherwise normal conditions, unilateral disconnection of centrifugal neurons in the chick affected eye development, inducing a reduced rate of axial elongation that resulted in a unilateral hyperopia in the eye contralateral to the lesion. Here, we further investigate the role of centrifugal neurons in ocular development in chicks reared in an abnormal visual environment, namely constant light. The baseline ocular phenotype of constant light-reared chicks (n = 8) with intact centrifugal neurons was assessed over a 3-week post-hatch time period and, subsequently, compared to chicks raised in normal diurnal lighting (n = 8). Lesions of the isthmo-optic tract or sham surgeries were performed in another seventeen chicks, all raised under constant light. Ocular phenotyping was performed over a 21-day postoperative period to assess changes in refractive state (streak retinoscopy) and ocular component dimensions (A-scan ultrasonography). A pathway-tracing paradigm was employed to quantify lesion success. Chicks raised in constant light conditions with an intact CVS developed shallower anterior chambers combined with elongated vitreous chambers relative to chicks raised in normal diurnal lighting. Seven days following surgery to disrupt centrifugal neurons, a significant positive correlation between refractive error asymmetry between the eyes and lesion success was evident, characterized by hyperopia in the eye contralateral to the lesion. By 21 days post-surgery, these contralateral eyes had become emmetropic, while ipsilateral eyes had developed relative axial hyperopia. Our results provide further support for the hypothesis that the centrifugal visual system can modulate eye development.
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Affiliation(s)
| | - Jeremy Andrew Guggenheim
- School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, Wales, UK
| | - Jonathan Thor Erichsen
- School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, Wales, UK.
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Abstract
Ocular clocks, first identified in the retina, are also found in the retinal pigment epithelium (RPE), cornea, and ciliary body. The retina is a complex tissue of many cell types and considerable effort has gone into determining which cell types exhibit clock properties. Current data suggest that photoreceptors as well as inner retinal neurons exhibit clock properties with photoreceptors dominating in nonmammalian vertebrates and inner retinal neurons dominating in mice. However, these differences may in part reflect the choice of circadian output, and it is likely that clock properties are widely dispersed among many retinal cell types. The phase of the retinal clock can be set directly by light. In nonmammalian vertebrates, direct light sensitivity is commonplace among body clocks, but in mice only the retina and cornea retain direct light-dependent phase regulation. This distinguishes the retina and possibly other ocular clocks from peripheral oscillators whose phase depends on the pace-making properties of the hypothalamic central brain clock, the suprachiasmatic nuclei (SCN). However, in mice, retinal circadian oscillations dampen quickly in isolation due to weak coupling of its individual cell-autonomous oscillators, and there is no evidence that retinal clocks are directly controlled through input from other oscillators. Retinal circadian regulation in both mammals and nonmammalian vertebrates uses melatonin and dopamine as dark- and light-adaptive neuromodulators, respectively, and light can regulate circadian phase indirectly through dopamine signaling. The melatonin/dopamine system appears to have evolved among nonmammalian vertebrates and retained with modification in mammals. Circadian clocks in the eye are critical for optimum visual function where they play a role fine tuning visual sensitivity, and their disruption can affect diseases such as glaucoma or retinal degeneration syndromes.
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Affiliation(s)
- Joseph C Besharse
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI
| | - Douglas G McMahon
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
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Lan W, Yang Z, Feldkaemper M, Schaeffel F. Changes in dopamine and ZENK during suppression of myopia in chicks by intense illuminance. Exp Eye Res 2016; 145:118-124. [DOI: 10.1016/j.exer.2015.11.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 11/20/2015] [Accepted: 11/25/2015] [Indexed: 11/25/2022]
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Nebbioso M, Plateroti AM, Pucci B, Pescosolido N. Role of the dopaminergic system in the development of myopia in children and adolescents. J Child Neurol 2014; 29:1739-46. [PMID: 24996871 DOI: 10.1177/0883073814538666] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This review summarizes the experimental evidence that supports the role of dopamine in the regulation of ocular axial growth. The most important functions attributed to dopamine are light adaptation and regulation of the retinal circadian rhythm. An increase of the retinal levels of dopamine activates D1 and D2 dopaminergic receptors present throughout the retina, generating a signal that inhibits axial growth once the eye has reached emmetropization. Researchers induced form-deprivation myopia in animal models in order to assess the different changes of ocular axial growth. Other studies have shown that phenylethylamine is an endogenous precursor-neurotransmitter capable of modulating the activity of dopamine. Considering the role of the dopaminergic system in the development of myopia (in children and adolescents) and the fact that phenylethylamine improves the consequences of a dopamine deficit, it would be interesting to study the effect of phenylethylamine on the regulation of axial growth, which represents the genesis of myopia.
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Affiliation(s)
- Marcella Nebbioso
- Department of Sense Organs, Sapienza University of Rome, Rome, Italy
| | | | - Bruna Pucci
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Nicola Pescosolido
- Department of Cardiovascular, Respiratory, Nephrology, Geriatric, and Anesthetic Sciences, Sapienza University of Rome, Rome, Italy
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He L, Frost MR, Siegwart JT, Norton TT. Gene expression signatures in tree shrew choroid in response to three myopiagenic conditions. Vision Res 2014; 102:52-63. [PMID: 25072854 DOI: 10.1016/j.visres.2014.07.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 06/23/2014] [Accepted: 07/10/2014] [Indexed: 11/18/2022]
Abstract
We examined gene expression in tree shrew choroid in response to three different myopiagenic conditions: minus lens (ML) wear, form deprivation (FD), and continuous darkness (DK). Four groups of tree shrews (n=7 per group) were used. Starting 24 days after normal eye opening (days of visual experience [DVE]), the ML group wore a monocular -5D lens for 2 days. The FD group wore a monocular translucent diffuser for 2 days. The DK group experienced continuous darkness binocularly for 11 days, starting at 17 DVE. An age-matched normal group was examined at 26 DVE. Quantitative PCR was used to measure the relative (treated eye vs. control eye) differences in mRNA levels in the choroid for 77 candidate genes. Small myopic changes were observed in the treated eyes (relative to the control eyes) of the ML group (-1.0±0.2D; mean±SEM) and FD group (-1.9±0.2D). A larger myopia developed in the DK group (-4.4±1.0D) relative to Normal eyes (both groups, mean of right and left eyes). In the ML group, 28 genes showed significant differential mRNA expression; eighteen were down-regulated. A very similar pattern occurred in the FD group; twenty-seven of the same genes were similarly regulated, along with five additional genes. Fewer expression differences in the DK group were significant compared to normal or the control eyes of the ML and FD groups, but the pattern was similar to that of the ML and FD differential expression patterns. These data suggest that, at the level of the choroid, the gene expression signatures produced by "GO" emmetropization signals are highly similar despite the different visual conditions.
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Affiliation(s)
- Li He
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, United States
| | - Michael R Frost
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, United States.
| | - John T Siegwart
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, United States
| | - Thomas T Norton
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, United States
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Xiao H, Fan ZY, Tian XD, Xu YC. Comparison of form-deprived myopia and lens-induced myopia in guinea pigs. Int J Ophthalmol 2014; 7:245-50. [PMID: 24790865 DOI: 10.3980/j.issn.2222-3959.2014.02.10] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Accepted: 10/08/2013] [Indexed: 11/02/2022] Open
Abstract
AIM To study the efficacy difference between form-deprived myopia (FDM) and lens-induced myopia (LIM), the degree of myopia, axial length and pathological changes of the posterior sclera from guinea pigs were evaluated. METHODS Four-week pigmented guinea pigs were randomly assigned into 3 groups, including normal control (n=6), FDM group with monocular cover (n=11) and LIM group with monocular -7D lens treatment (n=11). FDM group was form-deprived while LIM group was lens-induced for 14 d. Refractive error and axial length were measured prior to and post treatment, respectively. Morphological changes of sclera were examined using both light and electronic microscopes. RESULTS After 14d treatment, refractive errors for FDM group and LIM group were -3.05±0.71D and -2.12±1.29D, respectively, which were significantly more myopic than that of normal controls and fellow control eyes (P<0.01). As for axial length, it was 7.93±0.03 mm for FDM group and 7.89±0.06 mm for LIM group, which were significantly longer than both normal and fellow controls (P<0.01). With respect to both refractory error and axial length, the differences between FDM group and LIM group were not significant (P>0.05). Under light microscope, both FDM group and LIM group showed thinned sclera, disarrangement of fibrosis and enlarged disassociation between fibers. Consistently, ultrastructural examination showed degenerated fibroblasts and thinned fibers in posterior sclera. CONCLUSION Following two weeks of myopia induction in guinea pigs, with regard to the degree of myopia, axial length and pathological alterations, there was no significant difference between FDM and LIM models. Therefore, FDM and LIM are equally effective and useful as a model of experimental myopia and guinea pigs are ideal animals for induction of experimental myopia because their high sensitivity to both form-deprivation and lens-induction.
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Affiliation(s)
- Hui Xiao
- Department of Ophthalmology, the First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning Province, China ; Department of Ophthalmology, the 463th Hospital of the People's Liberation Army, Shenyang 110042, Liaoning Province, China
| | - Zhong-Yi Fan
- Department of Ophthalmology, the 463th Hospital of the People's Liberation Army, Shenyang 110042, Liaoning Province, China
| | - Xiao-Dan Tian
- Department of Ophthalmology, the Fourth People's Hospital of Shenyang, Shenyang 110000, Liaoning Province, China
| | - Yan-Chun Xu
- Department of Ophthalmology, the First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning Province, China
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McMahon DG, Iuvone PM, Tosini G. Circadian organization of the mammalian retina: from gene regulation to physiology and diseases. Prog Retin Eye Res 2013; 39:58-76. [PMID: 24333669 DOI: 10.1016/j.preteyeres.2013.12.001] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 11/27/2013] [Accepted: 12/01/2013] [Indexed: 01/27/2023]
Abstract
The retinal circadian system represents a unique structure. It contains a complete circadian system and thus the retina represents an ideal model to study fundamental questions of how neural circadian systems are organized and what signaling pathways are used to maintain synchrony of the different structures in the system. In addition, several studies have shown that multiple sites within the retina are capable of generating circadian oscillations. The strength of circadian clock gene expression and the emphasis of rhythmic expression are divergent across vertebrate retinas, with photoreceptors as the primary locus of rhythm generation in amphibians, while in mammals clock activity is most robust in the inner nuclear layer. Melatonin and dopamine serve as signaling molecules to entrain circadian rhythms in the retina and also in other ocular structures. Recent studies have also suggested GABA as an important component of the system that regulates retinal circadian rhythms. These transmitter-driven influences on clock molecules apparently reinforce the autonomous transcription-translation cycling of clock genes. The molecular organization of the retinal clock is similar to what has been reported for the SCN although inter-neural communication among retinal neurons that form the circadian network is apparently weaker than those present in the SCN, and it is more sensitive to genetic disruption than the central brain clock. The melatonin-dopamine system is the signaling pathway that allows the retinal circadian clock to reconfigure retinal circuits to enhance light-adapted cone-mediated visual function during the day and dark-adapted rod-mediated visual signaling at night. Additionally, the retinal circadian clock also controls circadian rhythms in disk shedding and phagocytosis, and possibly intraocular pressure. Emerging experimental data also indicate that circadian clock is also implicated in the pathogenesis of eye disease and compelling experimental data indicate that dysfunction of the retinal circadian system negatively impacts the retina and possibly the cornea and the lens.
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Affiliation(s)
- Douglas G McMahon
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - P Michael Iuvone
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, USA; Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, 30310 GA, USA.
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30
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Morgan IG, Ashby RS, Nickla DL. Form deprivation and lens-induced myopia: are they different? Ophthalmic Physiol Opt 2013; 33:355-61. [PMID: 23662966 DOI: 10.1111/opo.12059] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In the following point-counterpoint article, internationally-acclaimed myopia researchers were challenged to defend the two opposing sides of the topic defined by the title; their contributions, which appear in the order Point followed by Counterpoint, were peer-reviewed by both the editorial team and an external reviewer. Independently of the invited authors, the named member of the editorial team provided an Introduction and Summary, both of which were reviewed by the other members of the editorial team. By their nature, views expressed in each section of the Point-Counterpoint article are those of the author concerned and may not reflect the views of all of the authors.
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Affiliation(s)
- Ian G Morgan
- Research School of Biology, ARC Centre of Excellence in Vision Science, Australian National University, Canberra, Australia.
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31
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Guo L, Frost MR, He L, Siegwart JT, Norton TT. Gene expression signatures in tree shrew sclera in response to three myopiagenic conditions. Invest Ophthalmol Vis Sci 2013; 54:6806-19. [PMID: 24045991 DOI: 10.1167/iovs.13-12551] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE We compared gene expression signatures in tree shrew sclera produced by three different visual conditions that all produce ocular elongation and myopia: minus-lens wear, form deprivation, and dark treatment. METHODS Six groups of tree shrews (n = 7 per group) were used. Starting 24 days after normal eye-opening (days of visual experience [DVE]), two minus-lens groups wore a monocular -5 diopter (D) lens for 2 days (ML-2) or 4 days (ML-4); two form-deprivation groups wore a monocular translucent diffuser for 2 days (FD-2) or 4 days (FD-4). A dark-treatment (DK) group was placed in continuous darkness for 11 days after experiencing a light/dark environment until 17 DVE. A normal colony-reared group was examined at 28 DVE. Quantitative PCR was used to measure the relative differences in mRNA levels for 55 candidate genes in the sclera that were selected, either because they showed differential expression changes in previous ML studies or because a whole-transcriptome analysis suggested they would change during myopia development. RESULTS The treated eyes in all groups responded with a significant myopic shift, indicating that the myopia was actively progressing. In the ML-2 group, 27 genes were significantly downregulated in the treated eyes, relative to control eyes. In the treated eyes of the FD-2 group, 16 of the same genes also were significantly downregulated and one was upregulated. The two gene expression patterns were significantly correlated (r(2) = 0.90, P < 0.001). After 4 days of treatment, 31 genes were significantly downregulated in the treated eyes of the ML-4 group and three were upregulated. Twenty-nine of the same genes (26 down- and 3 up-regulated) and six additional genes (all downregulated) were significantly affected in the FD-4 group. The response patterns were highly correlated (r(2) = 0.95, P < 0.001). When the DK group (mean of right and left eyes) was compared to the control eyes of the ML-4 group, the direction and magnitude of the gene expression patterns were similar to those of the ML-4 (r(2) = 0.82, P < 0.001, excluding PENK). Similar patterns also were found when the treated eyes of the ML-4, FD-4, and DK groups were compared to the age-matched normal eyes. CONCLUSIONS The very similar gene expression signatures produced in the sclera by the three different myopiagenic visual conditions at different time points suggests that there is a "scleral remodeling signature" in this mammal, closely related to primates. The scleral genes examined did not distinguish between the specific visual stimuli that initiate the signaling cascade that results in axial elongation and myopia.
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Affiliation(s)
- Lin Guo
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama
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Alvarez AA, Wildsoet CF. Quantifying light exposure patterns in young adult students. JOURNAL OF MODERN OPTICS 2013; 60:1200-1208. [PMID: 25342873 PMCID: PMC4204734 DOI: 10.1080/09500340.2013.845700] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Exposure to bright light appears to be protective against myopia in both animals (chicks, monkeys) and children, but quantitative data on human light exposure are limited. In this study, we report on a technique for quantifying light exposure using wearable sensors. Twenty-seven young adult subjects wore a light sensor continuously for two weeks during one of three seasons, and also completed questionnaires about their visual activities. Light data were analyzed with respect to refractive error and season, and the objective sensor data were compared with subjects' estimates of time spent indoors and outdoors. Subjects' estimates of time spent indoors and outdoors were in poor agreement with durations reported by the sensor data. The results of questionnaire-based studies of light exposure should thus be interpreted with caution. The role of light in refractive error development should be investigated using multiple methods such as sensors to complement questionnaires.
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Affiliation(s)
- Amanda A. Alvarez
- Vision Science Graduate Group, School of Optometry, University of
California, Berkeley 588 Minor Hall, Berkeley, CA 94720-2020, USA
| | - Christine F. Wildsoet
- Vision Science Graduate Group, School of Optometry, University of
California, Berkeley 588 Minor Hall, Berkeley, CA 94720-2020, USA
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Tkatchenko TV, Shen Y, Braun RD, Bawa G, Kumar P, Avrutsky I, Tkatchenko AV. Photopic visual input is necessary for emmetropization in mice. Exp Eye Res 2013; 115:87-95. [PMID: 23838522 DOI: 10.1016/j.exer.2013.06.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 06/18/2013] [Accepted: 06/25/2013] [Indexed: 10/26/2022]
Abstract
It was recently demonstrated that refractive errors in mice stabilize around emmetropic values during early postnatal development, and that they develop experimental myopia in response to both visual form deprivation and imposed optical defocus similar to other vertebrate species. Animal studies also suggest that photopic vision plays critical role in emmetropization in diurnal species; however, it is unknown whether refractive eye development is guided by photopic vision in the mouse, which is a nocturnal species. We used an infrared mouse photorefractor and a high-resolution MRI to clarify the role of photopic visual input in refractive eye development in the mouse. Refractive eye development and form-deprivation myopia in P21-P89 C57BL/6J mice were analyzed under 12:12 h light-dark cycle, constant light and constant darkness regimens. Animals in all experimental groups were myopic at P21 (-13.2 ± 1.6 D, light-dark cycle; -12.5 ± 0.9 D, constant light; -12.5 ± 2.0 D, constant dark). The mean refractive error in the light-dark-cycle-reared animals was -0.5 ± 1.3 D at P32 and, and did not change significantly until P40 (+0.3 ± 0.6 D, P40). Animals in this group became progressively hyperopic between P40 and P89 (+2.2 ± 0.6 D, P67; +3.7 ± 2.0 D, P89). The mean refractive error in the constant-light-reared mice was -1.0 ± 0.7 D at P32 and remained stable until P89 (+0.1 ± 0.6 D, P40; +0.3 ± 0.6 D, P67; 0.0 ± 0.4 D, P89). Dark-reared animals exhibited highly hyperopic refractive errors at P32 (+5.2 ± 1.8 D) and became progressively more hyperopic with age (+8.7 ± 1.9 D, P40; +11.2 ± 1.4 D, P67). MRI analysis revealed that emmetropization in the P40-P89 constant-light-reared animals was associated with larger eyes, a longer axial length and a larger vitreous chamber compared to the light-dark-cycle-reared mice. Constant-light-reared mice also developed 4 times higher degrees of form-deprivation myopia on average compared to light-dark-cycle-reared animals (-12.0 ± 1.4 D, constant light; -2.7 ± 0.7 D, light-dark cycle). Dark-rearing completely prevented the development of form-deprivation myopia (-0.3 ± 0.5 D). Thus, photopic vision plays important role in normal refractive eye development and ocular response to visual form deprivation in the mouse.
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Affiliation(s)
- Tatiana V Tkatchenko
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, United States
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Feldkaemper M, Schaeffel F. An updated view on the role of dopamine in myopia. Exp Eye Res 2013; 114:106-19. [PMID: 23434455 DOI: 10.1016/j.exer.2013.02.007] [Citation(s) in RCA: 245] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 01/23/2013] [Accepted: 02/05/2013] [Indexed: 10/27/2022]
Abstract
A large body of data is available to support the hypothesis that dopamine (DA) is one of the retinal neurotransmitters involved in the signaling cascade that controls eye growth by vision. Initially, reduced retinal DA levels were observed in eyes deprived of sharp vision by either diffusers ("deprivation myopia", DM) or negative lenses ("lens induced myopia", LIM). Simulating high retinal DA levels by intravitreal application of a DA agonist can suppress the development of both DM and LIM. Also more recent studies using knock-out mouse models of DA receptors support the idea of an association between decreased DA levels and DM. There seem to be differences in the magnitude of the effects of DA on DM and LIM, with larger changes in DM but the degrees of image degradation by both treatments need to be matched to support this conclusion. Although a number of studies have shown that the inhibitory effects of dopamine agonists on DM and LIM are mediated through stimulation of the D2-receptor, there is also recent evidence that the balance of D2- and D1-receptor activation is important. Inhibition of D2-receptors can also slow the development of spontaneous myopia in albino guinea pigs. Retinal DA content displays a distinct endogenous diurnal, and partially circadian rhythm. In addition, retinal DA is regulated by a number of visual stimuli like retinal illuminance, spatial frequency content of the image, temporal contrast and, in chicks, by the light input from the pineal organ. A close interaction was found between muscarinergic and dopaminergic systems, and between nitric oxide and dopaminergic pathways, and there is evidence for crosstalk between the different pathways, perhaps multiple binding of the ligands to different receptors. It was shown that DA agonists interact with the immediate early signaling molecule ZENK which triggers the first steps in eye growth regulation. However, since long treatment periods were often needed to induce significant changes in retinal dopamine synthesis and release, the role of dopamine in the early steps is unclear. The wide spatial distribution of dopaminergic amacrine cells in the retina and the observation that changes in dopamine levels can be locally induced by local retinal deprivation is in line with the assumption that dopaminergic mechanisms control both central and peripheral eye growth. The protective effect of outdoor activity on myopia development in children seems to be partly mediated by the stimulatory effect of light on retinal dopamine production and release. However, the dose-response function linking light exposure to dopamine and to the suppression of myopia is not known and requires further studies.
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Affiliation(s)
- Marita Feldkaemper
- Centre for Ophthalmology, Institute for Ophthalmic Research, Section of Neurobiology of the Eye, Calwerstraße 7/1, 72076 Tuebingen, Germany.
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Stone RA, Pardue MT, Iuvone PM, Khurana TS. Pharmacology of myopia and potential role for intrinsic retinal circadian rhythms. Exp Eye Res 2013; 114:35-47. [PMID: 23313151 DOI: 10.1016/j.exer.2013.01.001] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 12/22/2012] [Accepted: 01/02/2013] [Indexed: 12/27/2022]
Abstract
Despite the high prevalence and public health impact of refractive errors, the mechanisms responsible for ametropias are poorly understood. Much evidence now supports the concept that the retina is central to the mechanism(s) regulating emmetropization and underlying refractive errors. Using a variety of pharmacologic methods and well-defined experimental eye growth models in laboratory animals, many retinal neurotransmitters and neuromodulators have been implicated in this process. Nonetheless, an accepted framework for understanding the molecular and/or cellular pathways that govern postnatal eye development is lacking. Here, we review two extensively studied signaling pathways whose general roles in refractive development are supported by both experimental and clinical data: acetylcholine signaling through muscarinic and/or nicotinic acetylcholine receptors and retinal dopamine pharmacology. The muscarinic acetylcholine receptor antagonist atropine was first studied as an anti-myopia drug some two centuries ago, and much subsequent work has continued to connect muscarinic receptors to eye growth regulation. Recent research implicates a potential role of nicotinic acetylcholine receptors; and the refractive effects in population surveys of passive exposure to cigarette smoke, of which nicotine is a constituent, support clinical relevance. Reviewed here, many puzzling results inhibit formulating a mechanistic framework that explains acetylcholine's role in refractive development. How cholinergic receptor mechanisms might be used to develop acceptable approaches to normalize refractive development remains a challenge. Retinal dopamine signaling not only has a putative role in refractive development, its upregulation by light comprises an important component of the retinal clock network and contributes to the regulation of retinal circadian physiology. During postnatal development, the ocular dimensions undergo circadian and/or diurnal fluctuations in magnitude; these rhythms shift in eyes developing experimental ametropia. Long-standing clinical ideas about myopia in particular have postulated a role for ambient lighting, although molecular or cellular mechanisms for these speculations have remained obscure. Experimental myopia induced by the wearing of a concave spectacle lens alters the retinal expression of a significant proportion of intrinsic circadian clock genes, as well as genes encoding a melatonin receptor and the photopigment melanopsin. Together this evidence suggests a hypothesis that the retinal clock and intrinsic retinal circadian rhythms may be fundamental to the mechanism(s) regulating refractive development, and that disruptions in circadian signals may produce refractive errors. Here we review the potential role of biological rhythms in refractive development. While much future research is needed, this hypothesis could unify many of the disparate clinical and laboratory observations addressing the pathogenesis of refractive errors.
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Affiliation(s)
- Richard A Stone
- Department of Ophthalmology, University of Pennsylvania School of Medicine, Scheie Eye Institute, D-603 Richards Building, Philadelphia, PA 19104-6075, USA.
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Huang J, Hung LF, Smith EL. Recovery of peripheral refractive errors and ocular shape in rhesus monkeys (Macaca mulatta) with experimentally induced myopia. Vision Res 2012; 73:30-9. [PMID: 23026012 DOI: 10.1016/j.visres.2012.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/03/2012] [Accepted: 09/06/2012] [Indexed: 10/27/2022]
Abstract
This study aimed to investigate the changes in ocular shape and relative peripheral refraction during the recovery from myopia produced by form deprivation (FD) and hyperopic defocus. FD was imposed in six monkeys by securing a diffuser lens over one eye; hyperopic defocus was produced in another six monkeys by fitting one eye with -3D spectacle. When unrestricted vision was re-established, the treated eyes recovered from the vision-induced central and peripheral refractive errors. The recovery of peripheral refractive errors was associated with corresponding changes in the shape of the posterior globe. The results suggest that vision can actively regulate ocular shape and the development of central and peripheral refractions in infant primates.
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Affiliation(s)
- Juan Huang
- College of Optometry, University of Houston, Houston, TX, United States
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Zhang Y, Liu Y, Wildsoet CF. Bidirectional, optical sign-dependent regulation of BMP2 gene expression in chick retinal pigment epithelium. Invest Ophthalmol Vis Sci 2012; 53:6072-80. [PMID: 22879416 DOI: 10.1167/iovs.12-9917] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
PURPOSE We explored the role of bone morphogenic protein 2 (BMP2) in defocus-induced ocular growth using gene expression changes in RPE as a surrogate. METHODS Young White-Leghorn chickens were used in this study. Normal gene expression of BMP2 and its receptors was examined in retina, RPE, and choroid, and BMP2 protein expression assessed in the same tissues using Western blots and immunohistochemistry. Quantitative PCR (qPCR) was used to assess the effects of short-term exposure (2 or 48 hours) to monocular +10 and -10 diopter (D) lenses, on RPE gene expression of BMP2 and its receptors. Ocular growth was assessed using A-scan ultrasonography. RESULTS In the eyes of untreated chickens, BMP2 mRNA was expressed more highly in RPE compared to retina and choroid and all three tissues expressed BMP2 protein. The gene expression for all three receptors also was detected in these tissues, with BMPR2 showing highest and BMPR1B lowest expression. BMP2 was up-regulated in the RPE from eyes wearing +10 D lenses, which exhibited shorter than normal vitreous chambers (VCDs) and thickened choroids, while BMP2 was down-regulated in the RPE from eyes wearing -10 D lenses, which developed enlarged VCDs. These treatments did not induce differential expression of BMP receptors in RPE. CONCLUSIONS That mRNA expression of BMP2 in chick RPE shows bidirectional, defocus sign-dependent changes is suggestive of a role for BMP2 in eye growth regulation, although the diffuse ocular expression of BMP2 and its receptors suggests complex growth-modulatory signal pathways.
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Affiliation(s)
- Yan Zhang
- Center for Eye Disease & Development, Vision Science Program & School of Optometry, University of California, Berkeley, Berkeley, California 94720, USA.
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Cohen Y, Peleg E, Belkin M, Polat U, Solomon AS. Ambient illuminance, retinal dopamine release and refractive development in chicks. Exp Eye Res 2012; 103:33-40. [PMID: 22960317 DOI: 10.1016/j.exer.2012.08.004] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/29/2012] [Accepted: 08/09/2012] [Indexed: 11/29/2022]
Abstract
Form deprivation and low illuminance of ambient light are known to induce myopia in chicks. Low concentrations of retinal dopamine, a light-driven neurohormone, was previously shown to be associated with form deprivation myopia. In the present study we examined the dependence of retinal dopamine release in chicks on illuminance during light-dark cycles and in continuous light, and the role of retinal dopamine release in illuminance dependent refractive development. Newly hatched chicks (n = 166) were divided into two experimental groups, a dopamine (n = 88) and a refraction group (n = 78). Both groups were further divided into six illumination groups for exposure of chicks to illuminances of 50, 500 or 10,000 lux of incandescent illumination (referred to throughout as low, medium, and high illuminance, respectively), either under a light-dark cycle with lights on between 7 AM and 7 PM or under continuous illumination. For the dopamine experiment, chicks were euthanized and vitreous was extracted on day 14 post-hatching at 7, 8 AM and 1 PM. Vitreal dihydroxyphenylacetic acid (DOPAC) and dopamine concentrations were quantified by high-performance liquid chromatography coupled to electrochemical detection. For the refraction experiment, chicks underwent refraction, keratometry and A-scan ultrasonography on days 30, 60 and 90 post-hatching, and each of those measurements was correlated with vitreal DOPAC concentration measured at 1 PM (representing the index of retinal dopamine release). The results showed that under light-dark cycles, vitreal DOPAC concentration was strongly correlated with log illuminance, and was significantly correlated with the developing refraction, corneal radius of curvature, and axial length values. On day 90, low vitreal DOPAC concentrations were associated with myopia (-2.41 ± 1.23 D), flat cornea, deep anterior and vitreous chambers, and thin lens. Under continuous light, vitreal DOPAC concentrations measured at 1 PM in the low, medium, and high illuminance groups did not differ from the concentrations measured at 8 AM. On day 90, low DOPAC concentrations were associated with emmetropia (+0.63 ± 3.61), steep cornea, and shallow vitreous chamber. We concluded that ambient light over a log illuminance range of 1.69-4 is linearly related to vitreal DOPAC concentration. Under both light-dark cycles and continuous light, the intensity of ambient light regulates the release of retinal dopamine. Refractive development is associated with illuminance dependent dopamine release.
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Affiliation(s)
- Yuval Cohen
- Goldschleger Eye Research Institute, Tel Aviv University, 53621 Tel Hashomer, Israel.
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Nickla DL, Schroedl F. Parasympathetic influences on emmetropization in chicks: evidence for different mechanisms in form deprivation vs negative lens-induced myopia. Exp Eye Res 2012; 102:93-103. [PMID: 22828050 DOI: 10.1016/j.exer.2012.07.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 06/26/2012] [Accepted: 07/06/2012] [Indexed: 10/28/2022]
Abstract
Ciliary ganglionectomy inhibits the development of myopia in chicks (Schmid et al., 1999), but has no effect on the compensatory responses to spectacle lenses (Schmid and Wildsoet, 1996). This study was done to assess the potential influence of the other parasympathetic input to the choroid, the pterygopalatine ganglia, on the choroidal and axial responses to retinal defocus, and to form deprivation. 4-5 week-old chicks had one of the following surgeries to one eye: (1) Section (X) of the autonomic part of cranial N VII (input to the pterygopalatine ganglia) (PPGX, n = 16), (2) PPGX plus ciliary ganglionectomy (PPG/CGX, n = 23) or (3) PPGX plus superior cervical ganglionectomy (PPG/SCGX, n = 10). Experimental eyes were fitted with positive or negative lenses, or diffusers, several days after surgery. In one group of PPG/CGX, eyes did not wear any devices (n = 8). Intact (no surgery) controls were done for all visual manipulations (lenses or diffusers). Sham surgeries were done for the PPG/CGX condition (n = 4). Ocular dimensions were measured using A-scan ultrasonography prior to the surgery, 5 days later when visual devices were placed on the eyes, at the end of lens- or diffuser-wear, and in the case of diffusers, 4 days after diffuser removal to look at "recovery". Refractive errors were measured using a Hartinger's refractometer. IOP was measured in 7 PPG/CGX birds 7d after surgery. PPGX/CGX resulted in choroidal thickening (125 μm) and a decrease in IOP over one week post-surgery. It also prevented the development of myopia in response to form deprivation (X vs intact: 0.2 D vs -4.1 D; p < 0.005), by preventing the increase in axial elongation (250 μm vs 670 μm/5d; p < 0.005). In fact, growth rate slowed below normal (X vs fellow eyes: 250 μm vs 489 μm/5d; p = 0.002). By contrast, there were no effects of this lesion on the development of myopia in response to negative lenses (X vs intact: -5.4 D vs -5.3 D). All three lesions inhibited the compensatory choroidal thickening in response to myopic defocus (ANOVA, p = 0.0008), but had no effect on the thinning response to hyperopic defocus. These results argue for different underlying mechanisms for the growth responses to form deprivation vs negative lens wear. They also imply that choroidal thickening and thinning are not opposing elements of a single mechanism.
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Affiliation(s)
- Debora L Nickla
- Department of Biosciences, The New England College of Optometry, Boston, MA 02115, United States.
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Smith EL, Hung LF, Huang J. Protective effects of high ambient lighting on the development of form-deprivation myopia in rhesus monkeys. Invest Ophthalmol Vis Sci 2012; 53:421-8. [PMID: 22169102 DOI: 10.1167/iovs.11-8652] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
PURPOSE Time spent outdoors reduces the likelihood that children will develop myopia, possibly because light levels are much higher outdoors than indoors. To test this hypothesis, the effects of high ambient lighting on vision-induced myopia in monkeys were determined. METHODS Monocular form deprivation was imposed on eight infant rhesus monkeys. Throughout the rearing period (23 ± 2 to 132 ± 8 days), auxiliary lighting increased the cage-level illuminance from normal lighting levels (15-630 lux) to ∼25,000 lux for 6 hours during the middle of the daily 12-hour light cycle. Refractive development and axial dimensions were assessed by retinoscopy and ultrasonography, respectively. Comparison data were obtained in previous studies from 18 monocularly form-deprived and 32 normal monkeys reared under ordinary laboratory lighting. RESULTS Form deprivation produced axial myopia in 16 of 18 normal-light-reared monkeys. In contrast, only 2 of the 8 high-light-reared monkeys developed myopic anisometropias, and in 6 of these monkeys, the form-deprived eyes were more hyperopic than their fellow eyes. The treated eyes of the high-light-reared monkeys were more hyperopic than the form-deprived eyes of the normal-light-reared monkeys. In addition, both eyes of the high-light-reared monkeys were more hyperopic than those of normal monkeys. CONCLUSIONS High ambient lighting retards the development of form-deprivation myopia in monkeys. These results are in agreement with the hypothesis that the protective effects of outdoor activities against myopia in children are due to exposure to the higher light levels encountered outdoors. It is possible that therapeutic protection against myopia can be achieved by manipulating indoor lighting levels.
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Affiliation(s)
- Earl L Smith
- College of Optometry, University of Houston, Houston, Texas 77204-2020, USA.
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Nickla DL, Totonelly K. Dopamine antagonists and brief vision distinguish lens-induced- and form-deprivation-induced myopia. Exp Eye Res 2011; 93:782-5. [PMID: 21872586 DOI: 10.1016/j.exer.2011.08.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 08/03/2011] [Accepted: 08/03/2011] [Indexed: 11/25/2022]
Abstract
In eyes wearing negative lenses, the D2 dopamine antagonist spiperone was only partly effective in preventing the ameliorative effects of brief periods of vision (Nickla et al., 2010), in contrast to reports from studies using form-deprivation. The present study was done to directly compare the effects of spiperone, and the D1 antagonist SCH-23390, on the two different myopiagenic paradigms. 12-day old chickens wore monocular diffusers (form-deprivation) or -10 D lenses attached to the feathers with matching rings of Velcro. Each day for 4 days, 10 μl intravitreal injections of the dopamine D2/D4 antagonist spiperone (5 nmoles) or the D1 antagonist SCH-23390, were given under isoflurane anesthesia, and the diffusers (n = 16; n = 5, respectively) or lenses (n = 20; n = 6) were removed for 2 h immediately after. Saline injections prior to vision were done as controls (form-deprivation: n = 11; lenses: n = 10). Two other saline-injected groups wore the lenses (n = 12) or diffusers (n = 4) continuously. Axial dimensions were measured by high frequency A-scan ultrasonography at the start, and on the last day immediately prior to, and 3 h after the injection. Refractive errors were measured at the end of the experiment using a Hartinger's refractometer. In form-deprived eyes, spiperone, but not SCH-23390, prevented the ocular growth inhibition normally effected by the brief periods of vision (change in vitreous chamber depth, spiperone vs saline: 322 vs 211 μm; p = 0.01). By contrast, neither had any effect on negative lens-wearing eyes given similar unrestricted vision (210 and 234 μm respectively, vs 264 μm). The increased elongation in the spiperone-injected form-deprived eyes did not, however, result in a myopic shift, probably due to the inhibitory effect of the drug on anterior chamber growth (drug vs saline: 96 vs 160 μm; p < 0.01). Finally, spiperone inhibited the vision-induced transient choroidal thickening in form-deprived eyes, while SCH-23390 did not. These results indicate that the dopaminergic mechanisms mediating the protective effects of brief periods of unrestricted vision differ for form-deprivation versus negative lens-wear, which may imply different growth control mechanisms between the two.
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Stone RA, McGlinn AM, Baldwin DA, Tobias JW, Iuvone PM, Khurana TS. Image defocus and altered retinal gene expression in chick: clues to the pathogenesis of ametropia. Invest Ophthalmol Vis Sci 2011; 52:5765-77. [PMID: 21642623 DOI: 10.1167/iovs.10-6727] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
PURPOSE Because of the retina's role in refractive development, this study was conducted to analyze the retinal transcriptome in chicks wearing a spectacle lens, a well-established means of inducing refractive errors, to identify gene expression alterations and to develop novel mechanistic hypotheses about refractive development. METHODS One-week-old white Leghorn chicks wore a unilateral spectacle lens of +15 or -15 D for 6 hours or 3 days. With total RNA from the retina/(retinal pigment epithelium, RPE), chicken gene microarrays were used to compare gene expression levels between lens-wearing and contralateral control eyes (n = 6 chicks for each condition). Normalized microarray signal intensities were evaluated by analysis of variance, using a false discovery rate of <10% as the statistical criterion. Selected differentially expressed genes were validated by qPCR. RESULTS Very few retina/RPE transcripts were differentially expressed after plus lens wear. In contrast, approximately 1300 transcripts were differentially expressed under each of the minus lens conditions, with minimal overlap. For each condition, low fold-changes typified the altered transcriptome. Differentially regulated genes under the minus lens conditions included many potentially informative signaling molecules and genes whose protein products have roles in intrinsic retinal circadian rhythms. CONCLUSIONS Plus or minus lens wear induce markedly different, not opposite, alterations in retina/RPE gene expression. The initial retinal responses to defocus are quite different from those when the eye growth patterns are well established, suggesting that different mechanisms govern the initiation and persistence or progression of refractive errors. The gene lists identify promising signaling candidates and regulatory pathways for future study, including a potential role for circadian rhythms in refractive development.
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Affiliation(s)
- Richard A Stone
- Department of Ophthalmology, University of Pennsylvania School of Medicine, Scheie Eye Institute, Philadelphia, Pennsylvania 19104-6075, USA.
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Nickla DL, Totonelly K, Dhillon B. Dopaminergic agonists that result in ocular growth inhibition also elicit transient increases in choroidal thickness in chicks. Exp Eye Res 2010; 91:715-20. [PMID: 20801115 PMCID: PMC2962673 DOI: 10.1016/j.exer.2010.08.021] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 08/12/2010] [Accepted: 08/19/2010] [Indexed: 10/19/2022]
Abstract
The dopaminergic system has been implicated in ocular growth regulation in chicks and monkeys. In both, dopamine D2 agonists inhibit the development of myopia in response to form deprivation, and in chicks, to negative lenses as well. Because there is mounting evidence that the choroidal response to defocus plays a role in ocular growth regulation, we asked whether the effective agonists also elicit transient thickening of the choroid concomitant with the growth inhibition. Negative lenses mounted on velcro rings were worn on one eye starting at age 8-12 days. Intravitreal injections (20 μl; dose = 10 nmole) of the agonist (dissolved in saline) or saline, were given through the superior temporal sclera using a 30G needle. Eyes were injected daily at noon, for 4 days, and the lenses immediately replaced. Agonists used were apomorphine (non-specific; n = 17), quinpirole (D2; n = 10), SKF-38393 (D1; n = 9), and saline controls (n = 22). For the antagonists, the same protocol was used, but on each day, the lenses were removed for 2 h. Immediately prior to lens-removal, the antagonist was injected (20 μl; dose = 5 nmole). Antagonists used were methylergonovine (non-specific; n = 12), spiperone (D2; n = 20), SCH-23390 (D1; n = 6) and saline controls (n = 27). Comparisons to saline (continuous lens wear) controls were from the agonist experiment. Axial dimensions were measured using high frequency A-scan ultrasonography at the start of lens wear, and on day 4 prior to the injections, and then again 3 h later. Refractive errors were measured using a Hartinger's refractometer at the end of the experiment. Apomorphine and quinpirole inhibited the refractive response to the hyperopic defocus induced by the negative lenses (drug vs saline controls: -1.3 and 1.2 D vs -5.6 D; p < 0.005 for both). This effect was axial: both drugs prevented the excessive ocular elongation (change in axial length: 233 and 205 μm vs 417 μm; p < 0.01 for both). Both drugs were also associated with a transient thickening of the choroid over 3 h (41 and 32 μm vs -1 μm; p < 0.01; p = 0.059 respectively) that did not summate: choroids thinned significantly over the 4 day period in all lens-wearing eyes. Two daily hours of unrestricted vision during negative lens wear normally prevents the development of myopia. Spiperone and SCH-23390 inhibited the ameliorating effects of periods of vision on lens-induced refractive error (-2.9 and -2.8 D vs 0.6 D; p < 0.0001), however, the effects on neither axial length nor choroidal thickness were significant. These data support a role for both D1 and D2 receptors in the ocular growth responses.
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Affiliation(s)
- Debora L Nickla
- The New England College of Optometry, Dept. of Biosciences, 424 Beacon St., Boston, MA 02115, USA.
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Smith EL, Hung LF, Huang J, Blasdel TL, Humbird TL, Bockhorst KH. Effects of optical defocus on refractive development in monkeys: evidence for local, regionally selective mechanisms. Invest Ophthalmol Vis Sci 2010; 51:3864-73. [PMID: 20220051 PMCID: PMC2910632 DOI: 10.1167/iovs.09-4969] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 01/07/2010] [Accepted: 02/11/2010] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize the influence of optical defocus on ocular shape and the pattern of peripheral refraction in infant rhesus monkeys. METHODS Starting at 3 weeks of age, eight infant monkeys were reared wearing -3 diopter (D) spectacle lenses over one eye that produced relative hyperopic defocus in the nasal field (NF) but allowed unrestricted vision in the temporal field (NF group). Six infants were reared with monocular -3 D lenses that produced relative hyperopic defocus across the entire field of view. Control data were obtained from 11 normal monkeys. Refractive development was assessed by streak retinoscopy performed along the pupillary axis and at eccentricities of 15 degrees, 30 degrees, and 45 degrees along the vertical and horizontal meridians. Central axial dimensions and eye shape were assessed with magnetic resonance imaging. RESULTS In response to full-field hyperopic defocus, the eye developed relative central axial myopia, became less oblate, and exhibited relative peripheral hyperopia in both the nasal and the temporal hemifields. Conversely, nasal-field hyperopic defocus produced relative myopia that was largely restricted to the nasal hemifield; these alterations in the patterns of peripheral refraction in the NF monkeys were associated with local, region-specific alterations in vitreous chamber depth in the treated hemiretina. CONCLUSIONS Optically imposed defocus can alter the shape and pattern of peripheral refraction in infant primates. Like those of form deprivation, the effects of optical defocus in primates are dominated by mechanisms that integrate visual signals in a spatially restricted manner and exert their influence in a regionally selective manner.
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Affiliation(s)
- Earl L Smith
- College of Optometry, University of Houston, Houston, Texas 77204-2020, USA.
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Abstract
1. Poultry are naturally long-sighted when they hatch, becoming emmetropic by 6 weeks of age. However, Cobb and Ross broilers exposed to <or=12-h photoperiods rapidly learn to eat in the dark, a behaviour which could adversely affect the establishment of emmetropia. And so, in the current study, eyes were enucleated, post mortem, at 40 and 54 d from broilers given various photoperiods between 2 and 24 h, and eye weight determined to indirectly assess the extent to which photoperiod might affect ocular development. 2. In both genotypes, there was an inverse linear relationship between absolute eye weight and photoperiod up to 21 h, but continuously illuminated birds consistently had heavier eyes. When expressed relative to body weight, eye weight for <or=21-h birds was inversely related to the logarithm of photoperiod. 3. The slope of the regression of relative eye weight on <or=21-h photoperiod log values was significantly less at 54 d than at 40 d in both genotypes, but constantly illuminated birds continued to have above average eye weights. 4. Cobb birds invariably had heavier eyes than Ross, both in absolute and relative (to body weight) terms. 5. The results support previous work suggesting that there is a minimum period of daily darkness required to maintain chicken eye growth within the normal range and show that very short photoperiods, as well as ultra-long photoperiods and continuous illumination, adversely affect ocular development, with potential welfare implications.
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Affiliation(s)
- P D Lewis
- Animal and Poultry Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa.
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Tkatchenko TV, Shen Y, Tkatchenko AV. Mouse experimental myopia has features of primate myopia. Invest Ophthalmol Vis Sci 2009; 51:1297-303. [PMID: 19875658 DOI: 10.1167/iovs.09-4153] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Several recent studies have suggested that experimental myopia can be induced in mice. However, it is not clear what role the photopic visual input plays in this process and whether mouse myopia is similar to human myopia. The purpose of this study was to carry out an in vivo high-resolution analysis of changes in ocular components and refractive state of the eye upon induction of experimental myopia in mice. METHODS A high-resolution small animal MRI system and a high-resolution automated eccentric infrared photorefractor were used to analyze changes of the refractive state and ocular components in C57BL/6J mice associated with experimental myopia induced by diffusers and -25 D lenses under photopic conditions. RESULTS The authors found that both diffusers and -25 D lenses induce myopia in C57BL/6J mice under photopic conditions (continuous light, 200 +/- 15 lux). The extent of myopic shift induced by -25 D lenses was greater than the shift induced by diffusers (-15.2 +/- 0.7 D, lenses; -12.0 +/- 1.4 D, diffusers). Myopia in mice is attributed to an increase in size of the postequatorial segment of the eye. Experimental myopia in mice can be induced only during the susceptible period in postnatal development, which ends around postnatal day 67. CONCLUSIONS Both diffusers and spectacle lenses induce myopia in mice under photopic conditions, during the susceptible period in postnatal development. Myopia in mice is associated with elongation of the vitreous chamber of the eye, as in humans and nonhuman primates.
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Affiliation(s)
- Tatiana V Tkatchenko
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan 48201, USA.
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Smith EL, Hung LF, Huang J. Relative peripheral hyperopic defocus alters central refractive development in infant monkeys. Vision Res 2009; 49:2386-92. [PMID: 19632261 PMCID: PMC2745495 DOI: 10.1016/j.visres.2009.07.011] [Citation(s) in RCA: 281] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Revised: 07/17/2009] [Accepted: 07/20/2009] [Indexed: 10/20/2022]
Abstract
Understanding the role of peripheral defocus on central refractive development is critical because refractive errors can vary significantly with eccentricity and peripheral refractions have been implicated in the genesis of central refractive errors in humans. Two rearing strategies were used to determine whether peripheral hyperopia alters central refractive development in rhesus monkeys. In intact eyes, lens-induced relative peripheral hyperopia produced central axial myopia. Moreover, eliminating the fovea by laser photoablation did not prevent compensating myopic changes in response to optically imposed hyperopia. These results show that peripheral refractive errors can have a substantial impact on central refractive development in primates.
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Affiliation(s)
- Earl L Smith
- College of Optometry, University of Houston, Houston, TX 77204-2020, USA.
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Cohen Y, Belkin M, Yehezkel O, Avni I, Polat U. Light intensity modulates corneal power and refraction in the chick eye exposed to continuous light. Vision Res 2008; 48:2329-35. [DOI: 10.1016/j.visres.2008.07.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2008] [Revised: 07/06/2008] [Accepted: 07/15/2008] [Indexed: 10/21/2022]
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Padmanabhan V, Shih J, Wildsoet CF. Patching fellow eyes during subjective night does not prevent disruption to minus lens compensation in constant light-reared chicks. Vision Res 2008; 48:1992-8. [PMID: 18585401 PMCID: PMC2567919 DOI: 10.1016/j.visres.2008.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 05/23/2008] [Accepted: 06/02/2008] [Indexed: 11/16/2022]
Abstract
PURPOSE This study re-examined an earlier claim that monocular patching during subjective night (i.e. patched at the usual time that night would occur) in the chicks reared in continuous lighting (CL), offered unpatched eyes some protection from the ocular effects of CL. It also examined whether this monocular patching protected unpatched eyes against the disruptive effect of CL on compensation to minus lenses. METHODS Hatchling White-Leghorn chicks were reared in either constant or diurnal lighting conditions (n=28) for 2 weeks. Some CL chicks had their right eyes patched every night during the entire study. Lenses of either +10 or -10D power were fitted to the unpatched eyes of some patched chicks at the beginning of the second week. Retinoscopy, IR photo-keratometry and high-frequency A-scan ultrasonography were used to track refractions, corneal radius of curvature and ocular axial dimensions respectively; data were collected on experimental days 0, 7, 9 and 14. RESULTS The patched eyes were completely protected from the ocular growth effects of CL, i.e. accelerated posterior segment (vitreous chamber) growth and inhibited anterior segment growth. Although the unpatched eyes showed no protection from the anterior chamber effects of CL, they were completely protected from the effects of CL on vitreous chamber growth. Nonetheless, the response to the -10D lenses was disrupted in unpatched eyes, which responded in the wrong direction for compensation (+5.5+/-0.25D more hyperopic than no lens-unpatched eyes). The response to the +10D lenses was preserved (+9.25+/-0.25D more hyperopic than no lens-unpatched eyes). CONCLUSION These data provide further support for local control of emmetropization, as reflected in compensatory lens responses, but point to additional influences on eye growth as reflected in CL-induced ocular changes.
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Affiliation(s)
- Varuna Padmanabhan
- School of Optometry, University of California-Berkeley, Berkeley, CA 94720-2020, USA.
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Pardue MT, Faulkner AE, Fernandes A, Yin H, Schaeffel F, Williams RW, Pozdeyev N, Iuvone PM. High susceptibility to experimental myopia in a mouse model with a retinal on pathway defect. Invest Ophthalmol Vis Sci 2008; 49:706-12. [PMID: 18235018 DOI: 10.1167/iovs.07-0643] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Nob mice share the same mutation in the Nyx gene that is found in humans with complete congenital stationary night blindness (CSNB1). Nob mutant mice were studied to determine whether this defect resulted in myopia, as it does in humans. METHODS Refractive development was measured in unmanipulated wild-type C57BL/6J (WT) and nob mice from 4 to 12 weeks of age by using an infrared photorefractor. The right eye was form deprived by means of a skull-mounted goggling apparatus at 4 weeks of age. Refractive errors were recorded every 2 weeks after goggling. The content of dopamine and the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were measured by HPLC with electrochemical detection (HPLC-ECD) in retinas of nob and WT mice under light- and dark-adapted conditions. RESULTS The nob mice had greater hyperopic refractive errors than did the WT mice under normal visual conditions, until 12 weeks of age when both strains had similar refractions. At 6 weeks of age, refractions became less hyperopic in the nob mice but continued to become more hyperopic in the WT mice. After 2 weeks of form deprivation (6 weeks of age), the nob mice displayed a significant myopic shift (~4 D) in refractive error relative to the opposite and control eyes, whereas WT mice required 6 weeks of goggling to elicit a similar response. As expected with loss of ON pathway transmission, light exposure did not alter DOPAC levels in the nob mice. However, dopamine and DOPAC levels were significantly lower in the nob mice compared with WT. CONCLUSIONS Under normal laboratory visual conditions, only minor differences in refractive development were observed between the nob and WT mice. The largest myopic shift in the nob mice resulted after form deprivation, suggesting that visual pathways dependent on nyctalopin and/or abnormally low dopaminergic activity play a role in regulating refractive development. These findings demonstrate an interaction of genetics and environment in refractive development.
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Affiliation(s)
- Machelle T Pardue
- Rehabilitation Research and Development Center, Atlanta VA Medical Center, Decatur, GA 30033, USA.
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