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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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Nilsen NG, Gilson SJ, Pedersen HR, Hagen LA, Wildsoet CF, Baraas RC. The effect of topical 1 % atropine on ocular dimensions and diurnal rhythms of the human eye. Vision Res 2024; 214:108341. [PMID: 38065032 DOI: 10.1016/j.visres.2023.108341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/23/2023]
Abstract
The effect of topical 1 % atropine on the diurnal rhythms of the human eye was investigated. Participants wore an activity monitor on Days 1-7. A set of measures (epochs) encompassing intraocular pressure (IOP), ocular biometry, and retinal imaging were obtained on Day 7 (baseline), followed by eight epochs on Day 8, and one on Day 9 from both eyes of healthy participants (n = 22, 19-25 years). The sleep time of participants (collected via actigraphy) was used as a reference in scheduling epochs. Topical 1 % atropine was instilled in the dominant eye on Day 8, 2 h after habitual wake time, using the fellow eye as control (paired-eye design). Sinusoids with a 24-h period were fitted to the data, and a non-linear mixed-effects model was used to estimate rhythmic statistics. There were no interocular differences in any of the measured parameters at baseline. Comparing pre- versus post-atropine in treated eyes revealed lower IOP, deeper anterior chamber (ACD), decreased crystalline lens thickness and shorter axial length (AL). The same trends were observed when comparing atropine-treated versus fellow control eyes, except for IOP and AL (no differences). Both atropine-treated and fellow control eyes showed significant diurnal variations in all ocular parameters, with atropine-treated eyes revealing larger AL and retinal thickness amplitudes, smaller vitreous chamber depth (VCD) amplitudes, and a significant phase advancement for ACD and VCD. There were no interocular differences in choroidal thickness rhythms. In conclusion, while ocular diurnal rhythms persisted after instillation of 1 % atropine, many rhythmic parameters were altered.
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Affiliation(s)
- Nickolai G Nilsen
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway
| | - Stuart J Gilson
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway
| | - Hilde R Pedersen
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway
| | - Lene A Hagen
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway
| | - Christine F Wildsoet
- Herbert Wertheim School of Optometry & Vision Science, University of California Berkeley, USA
| | - Rigmor C Baraas
- National Centre for Optics, Vision and Eye Care, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway.
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Song D, Rong Y, Zhang C, Sun Y. The Relationship between Choroidal Thickness and Liver Damage in Simple Auto-immune Hepatitis Patients. Niger J Clin Pract 2023; 26:1910-1915. [PMID: 38158360 DOI: 10.4103/njcp.njcp_435_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 08/11/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND There was no sufficient clinical evidence on the relationship between auto-immune hepatitis (AIH) and risk of eye illness, except 11 uveitis cases where related AIH is reported currently. AIM To determine the relationship between choroidal thickness (ChT) and liver damage in simple AIH patients without ocular symptoms after oral prednisone treatment. PATIENTS AND METHODS This prospective observational study included simple AIH patients. The patients' ChT was measured by swept-source (SS)-optical coherence tomography (OCT), and the liver damage was evaluated by alanine aminotransferase (ALT) and aspartate aminotransferase (AST). ChT and liver functions were assessed prior to and after treatment. Then comparisons were made prior to and post treatment. The relationships between biochemical indexes of liver injury and ChT were evaluated after a mean (SD) of 24 (1.28) weeks of regular oral prednisone. RESULTS A total of 35 patients (31 females, aged 45.66 ± 11.62 years) were included. After treatment, ChT was significantly increased in all sectors (including the center sector, superior inner sector, inner nasal sector, inferior inner sector, inner temporal sector, superior outer sector, outer nasal sector, inferior outer sector, and outer temporal sector) (all P < 0.001). After treatment, both ALT (51.34 ± 44.16 vs 255.06 ± 107.84, P < 0.001) and AST (38.66 ± 27.12 vs 164.89 ± 85.58, P < 0.001) were significantly decreased. The increase of ChT in all sectors was significantly related to the decrease of ALT and AST (all P < 0.001). CONCLUSION The improvement of ChT might reflect the remission of liver damage in simple AIH patients without ocular symptoms during oral prednisone treatment.
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Affiliation(s)
- D Song
- Department of Ophthalmology, Beijing University International Hospital, No. 1 Shengmingyuan Road, Zhongguancun Life Science Park, Changping District, Beijing, China
| | - Y Rong
- Department of Liver Disease, Beijing University International Hospital, No. 1 Shengmingyuan Road, Zhongguancun Life Science Park, Changping District, Beijing, China
| | - C Zhang
- Department of Ophthalmology, Beijing University International Hospital, No. 1 Shengmingyuan Road, Zhongguancun Life Science Park, Changping District, Beijing, China
| | - Y Sun
- Department of Liver Disease-Senior Department of Hepatology, The Fifth Medical Center of PLA General Hospital, No. 100 Xisihuanzhong Road, Fengtai District, Beijing, China
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Obradović D, Pešić I, Čarapić M, Lazović S, Agbaba D. Analysis of scopolamine and its related substances by means of high-performance liquid chromatography. ACTA CHROMATOGR 2022. [DOI: 10.1556/1326.2022.01107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AbstractThe retention behaviour of scopolamine (hyoscine) and its related compounds (norhyoscine, atropine, homatropine, and noratropine) was investigated on the silica-based HPLC stationary phase. The retention of investigated tropane alkaloids was interpreted by using the Soczewiński-Wachtmeister equation. A high correlation between the retention parameter (log k) and lipophilicity (log P) (R = 0.9923) confirms the significant influence of hydrophobic interactions on the retention behaviour of the aforementioned compounds. It was found that by increasing the acetonitrile fraction, a decrease in retention of the more polar epoxide derivatives (scopolamine, norhyoscine) and an increase in retention of the more lipophilic derivatives (atropine, noratropine, homatropine) is obtained. The best separation of the tropane alkaloids was achieved by a simple procedure that involved a mobile phase composed of acetonitrile and 40 mM ammonium acetate/0.05% TEA, pH 6.5; 50:50 v/v. Selected conditions were assumed for the determination of scopolamine hydrochloride in the eye drops (Scopolamini hydrobromidum 0.25%). The method was validated and it was found as selective, sensitive, precise, accurate, and robust for the further qualitative analysis of the scopolamine-related compounds.
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Affiliation(s)
- Darija Obradović
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Ivana Pešić
- Service for the Pharmaceutical Business and Supply, Clinical Center of Serbia, Pasterova 2, 11000 Belgrade, Serbia
| | - Marija Čarapić
- Medicines and Medical Devices Agency of Serbia, Vojvode Stepe 458, 11000 Belgrade, Serbia
| | - Saša Lazović
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Danica Agbaba
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11000 Belgrade, Serbia
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Accommodation is Decreased in Eyes with Acute Central Serous Chorioretinopathy. Optom Vis Sci 2022; 99:687-691. [PMID: 35678631 DOI: 10.1097/opx.0000000000001914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE This is a case-control study showing changes in accommodation in eyes with acute central serous chorioretinopathy. Decreased accommodative amplitude we found in affected eyes may indicate suppression of parasympathetic activity in those eyes as one of the pathophysiological mechanisms controlling choroidal thickness and perfusion. PURPOSE To evaluate the changes of accommodation in patients with acute central serous chorioretinopathy (CSC). METHODS Patients with unilateral CSC, with and without foveal involvement as well as patients after resolution of subretinal fluid, and healthy age-matched controls were included. Accommodative amplitude was measured and compared between eyes with active or resolved CSC, fellow eyes of active CSC individuals and eyes of controls. Correlation between accommodative amplitude and ocular and demographic parameters was calculated. RESULTS Nineteen acute CSC patients (16 males and 3 females, 38.1 ± 5.1 years) and 17 age-matched controls (13 males and 4 females, 37.2 ± 5.4 years) were included. Accommodative amplitude in study eyes of CSC patients was lower than in the fellow unaffected eyes, 1.25 ± 1.0 D and 2.54 ± 0.94 D, respectively (P = .002) or in the eyes of healthy controls (2.41 ± 1.38 D, P = .002). In CSC eyes after resolution of subretinal fluid or without foveal involvement the median accommodative amplitude was lower than in fellow eyes, 1.6 D (95% CI 0.83 to 1.75) and 2.7 D (95% CI 1.23 to 3.61), respectively (P = .004). No correlation was found between accommodative amplitude in affected CSC eyes and different parameters, except for age (r = -0.47, P = .04). CONCLUSIONS Acute CSC is associated with a substantial reduction of accommodative amplitude.
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Asmussen A, Smith BS, Møller F, Jakobsen TM. Repeatability and inter-observer variation of choroidal thickness measurements using swept-source optical coherence tomography in myopic danish children aged 6-14 years. Acta Ophthalmol 2022; 100:74-81. [PMID: 34126650 PMCID: PMC9291036 DOI: 10.1111/aos.14890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 02/27/2021] [Accepted: 04/11/2021] [Indexed: 11/08/2022]
Abstract
Purpose To estimate repeatability and inter‐observer variation of choroidal thickness measurements in myopic Danish children aged 7–14 years using swept‐source optical coherence tomography (SS‐OCT). Methods Thirty‐nine children were enrolled. Optical correction was single‐vision spectacles (SVS) or orthokeratology lenses (OKL). Three repeated 7 × 7 mm 3‐dimensional SS‐OCT macula scans and three repeated 9 mm SS‐OCT line scans were collected for each child using a DRI OCT Triton. Choroidal thickness was measured using three different methods: line scan method 1 (LM1), line scan method 2 (LM2) and 3D macula scan method (3DM). Segmentation was adjusted if needed. Coefficients of repeatability (CR) and limits of agreement (LoA) were calculated. Results The CRs ranged from 13.4 to 23.9 µm, 14.5 to 26.2 µm and 5.2 to 10.7 µm for LM1, LM2 and 3DM, respectively. The LoA ranged from −22.9 to +31.5 µm, −23.3 to +32.2 µm and −10.2 to +12.4 µm for LM1, LM2 and 3DM, respectively. Segmentation was adjusted in most scans (63%–92%). Mean choroidal thickness ranged from 142.2 ± 47.2 to 253.8 ± 60.9 µm and 190.1 ± 64.0 to 299.0 ± 55.8 µm for the SVS and OKL groups, respectively, measured by 3DM. Conclusion The 3DM was the most repeatable method in this paediatric population. It yielded a CR of 10.7 µm, confidence interval 2.4 µm, which makes the minimal detectable difference between two measurements 13.1 µm. Most inter‐observer variation could be explained by the intramethod variation. Segmentation adjustment on 3D macula scans did not increase CR on a group level.
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Affiliation(s)
| | | | - Flemming Møller
- Department of Ophthalmology Lillebaelt Hospital University Hospital of Southern Denmark Odense Denmark
| | - Trine M. Jakobsen
- Department of Ophthalmology Lillebaelt Hospital University Hospital of Southern Denmark Odense Denmark
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Guo B, Lau JK, Cheung SW, Cho P. Repeatability and reproducibility of manual choroidal thickness measurement using Lenstar images in children before and after orthokeratology treatment. Cont Lens Anterior Eye 2021; 45:101484. [PMID: 34303626 DOI: 10.1016/j.clae.2021.101484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 12/19/2022]
Abstract
PURPOSE To investigate the repeatability and reproducibility of choroidal thickness measurements using Lenstar images in young myopic children before and after one-month orthokeratology (ortho-k) treatment. METHOD Ocular biometry of 39 subjects were performed using the Lenstar 900. The first five measurements with maximum differences of 0.02 mm in axial length in the right eyes were saved and used for measurement of choroidal thickness. Subfoveal choroidal thickness were manually measured by identifying the signals from the retinal pigmented epithelium layer and chorioscleral interface. Repeatability was determined by comparing measurements of the same images made by the same observer on two separate occasions (four weeks apart), while reproducibility was calculated by comparing measurements of the same images made by two independent observers. Data was analysed using intra-class correlation coefficients (ICC) and non-parametric Bland and Altman plots. RESULTS The choroidal peaks could not be identified in all five measurements in all subjects. On average, only 71% subjects had at least four definable images. Compared with the use of fewer than four images, reliability using an average of four definable images improved statistically, but remained clinically unacceptable (>10 µm), although pre- and post-ortho-k ICC values were good to excellent for repeatability (0.867 and 0.975, respectively) and excellent and good for reproducibility (0.959 and 0.868, respectively). Non-parametric pre- and post-ortho-k limits of agreement (2.5% and 97.5% percentiles) obtained were -45.8 to 79.3 µm and -30.3 to 9.5 µm, respectively for repeatability, and -29.0 to 33.5 µm and -21.8 to 70.0 µm, respectively for reproducibility. CONCLUSION Choroidal thickness measurements using the Lenstar did not show good reliability, despite the high ICC values, non-parametric Bland and Altman plots demonstrated a wide variability of measurement errors. Any changes in subfoveal choroidal thickness, measured by Lenstar, of <80 µm may not represent real changes.
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Affiliation(s)
- Biyue Guo
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region.
| | - Jason K Lau
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region
| | - Sin Wan Cheung
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region
| | - Pauline Cho
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region
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Vincent SJ, Cho P, Chan KY, Fadel D, Ghorbani-Mojarrad N, González-Méijome JM, Johnson L, Kang P, Michaud L, Simard P, Jones L. CLEAR - Orthokeratology. Cont Lens Anterior Eye 2021; 44:240-269. [DOI: 10.1016/j.clae.2021.02.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 02/01/2021] [Indexed: 12/25/2022]
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Delshad S, Collins MJ, Read SA, Vincent SJ. The human axial length and choroidal thickness responses to continuous and alternating episodes of myopic and hyperopic blur. PLoS One 2020; 15:e0243076. [PMID: 33264356 PMCID: PMC7710071 DOI: 10.1371/journal.pone.0243076] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 11/14/2020] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To investigate the change in axial length (AxL) and choroidal thickness (ChT) in response to continuous and alternating episodes of monocular myopic and hyperopic defocus. METHODS The right eye of sixteen young adults was exposed to 60 minute episodes of either continuous or alternating myopic and hyperopic defocus (+3 DS & -3 DS) over six separate days, with the left eye optimally corrected for distance. During alternating defocus conditions, the eye was exposed to either 30 or 15 minute cycles of myopic and hyperopic defocus, with the order of defocus reversed in separate sessions. The AxL and ChT of the right eye were measured before, during and after each defocus condition. RESULTS Significant changes in AxL were observed over time, dependent upon the defocus condition (p < 0.0001). In general, AxL exhibited a greater magnitude of change during continuous than alternating defocus conditions. The maximum AxL elongation was +7 ± 7 μm (p = 0.010) in response to continuous hyperopic defocus and the maximum AxL reduction was -8 ± 10 μm of (p = 0.046) in response to continuous myopic defocus. During both 30 and 15 minute cycles of alternating myopic and hyperopic defocus of equal duration, the effect of opposing blur sessions cancelled each other and the AxL was near baseline levels following the final defocus session (mean change from baseline across all alternating defocus conditions was +2 ± 10 μm, p > 0.05). Similar, but smaller magnitude, changes were observed for ChT. CONCLUSIONS The human eye appears capable of temporal averaging of visual cues from alternating myopic and hyperopic defocus. In the short term, this integration appears to be a cancellation of the effects of the preceding defocus condition of opposite sign.
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Affiliation(s)
- Samaneh Delshad
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia
- * E-mail:
| | - Michael John Collins
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia
| | - Scott Andrew Read
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia
| | - Stephen James Vincent
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, School of Optometry and Vision Science, Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia
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Abstract
The review summarizes experimental and clinical data attesting to the important role the choroid plays in the development of refraction through optically oriented thickness changes and the release of growth factors. Because of its unique anatomical position, the choroid can influence the transmission of a cascade of chemical signals from the retina to the sclera and thereby affect the growth of the eye. Understanding the relationship between the optical defocus and the response of the choroid to it will help uncover the fundamental mechanisms for controlling eye growth and develop new strategies for preventing the progression of myopia.
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Affiliation(s)
- E P Tarutta
- Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - S V Milash
- Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - G A Markosyan
- Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - N A Tarasova
- Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
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Hughes RPJ, Read SA, Collins MJ, Vincent SJ. Changes in ocular biometry during short‐term accommodation in children. Ophthalmic Physiol Opt 2020; 40:584-594. [DOI: 10.1111/opo.12711] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/29/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Rohan P J Hughes
- Contact Lens and Visual Optics Laboratory School of Optometry and Vision Science Queensland University of Technology (QUT) Brisbane Queensland Australia
| | - Scott A Read
- Contact Lens and Visual Optics Laboratory School of Optometry and Vision Science Queensland University of Technology (QUT) Brisbane Queensland Australia
| | - Michael J Collins
- Contact Lens and Visual Optics Laboratory School of Optometry and Vision Science Queensland University of Technology (QUT) Brisbane Queensland Australia
| | - Stephen J Vincent
- Contact Lens and Visual Optics Laboratory School of Optometry and Vision Science Queensland University of Technology (QUT) Brisbane Queensland Australia
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The time course of the onset and recovery of axial length changes in response to imposed defocus. Sci Rep 2020; 10:8322. [PMID: 32433541 PMCID: PMC7239843 DOI: 10.1038/s41598-020-65151-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 04/20/2020] [Indexed: 12/18/2022] Open
Abstract
The human eye is capable of responding to the presence of blur by changing its axial length, so that the retina moves towards the defocused image plane. We measured how quickly the eye length changed in response to both myopic and hyperopic defocus and how quickly the eye length changed when the defocus was removed. Axial length was measured at baseline and every 10 minutes during 1 hour of exposure to monocular defocus (right eye) with the left eye optimally corrected for two defocus conditions (+3 D and −3 D) and a control condition. Recovery was measured for 20 minutes after blur removal. A rapid increase in axial length was observed after exposure (~2 minutes) to hyperopic defocus (+7 ± 5 μm, p < 0.001) while the reduction in axial length with myopic defocus was slower and only statistically significant after 40 minutes (−8 ± 9 μm, p = 0.017). The eye length also recovered toward baseline levels during clear vision more rapidly following hyperopic than myopic defocus (p < 0.0001). These findings provide evidence that the human eye is able to detect and respond to the presence and sign of blur within minutes.
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Short-Term Effect of Low-Dose Atropine and Hyperopic Defocus on Choroidal Thickness and Axial Length in Young Myopic Adults. J Ophthalmol 2019; 2019:4782536. [PMID: 31531235 PMCID: PMC6721261 DOI: 10.1155/2019/4782536] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/25/2019] [Accepted: 05/28/2019] [Indexed: 12/13/2022] Open
Abstract
Purpose To examine the interaction between a short period of hyperopic defocus and low-dose atropine upon the choroidal thickness and ocular biometrics of healthy myopic subjects. Methods Twenty young adult myopic subjects had subfoveal choroidal thickness (ChT) and ocular biometry measurements taken before and 30 and 60 min following the introduction of optical blur (0.00 D and −3.00 D) combined with administration of 0.01% atropine or placebo. Each combination of optical blur and drug was tested on different days in a fixed order. Results The choroid exhibited significant thinning after imposing hyperopic defocus combined with placebo (mean change of −11 ± 2 μm, p < 0.001). The combination of hyperopic blur and 0.01% atropine led to a significantly smaller magnitude of subfoveal choroidal thinning (−4 ± 8 μm), compared to placebo and hyperopic defocus (p < 0.01). Eyes treated with 0.01% atropine with no defocus exhibited a significant increase in ChT (+6 ± 2 μm, p < 0.01). Axial length also underwent small but significant changes after treatment with hyperopic blur and placebo and 0.01% atropine alone (both p < 0.01), but of opposite direction to the changes in choroidal thickness. However, the 0.01% atropine/hyperopic blur condition did not lead to a significant change in axial length compared to baseline (p > 0.05). Conclusion Low-dose atropine does inhibit the short-term effect of hyperopic blur on choroidal thickness and, when used alone, does cause a slight thickening of the choroid in young healthy myopic adults.
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Lau JK, Wan K, Cheung SW, Vincent SJ, Cho P. Weekly Changes in Axial Length and Choroidal Thickness in Children During and Following Orthokeratology Treatment With Different Compression Factors. Transl Vis Sci Technol 2019; 8:9. [PMID: 31360614 PMCID: PMC6656409 DOI: 10.1167/tvst.8.4.9] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 05/13/2019] [Indexed: 12/13/2022] Open
Abstract
Purpose To determine the influence of compression factor upon changes in axial length and choroidal thickness during and following orthokeratology treatment. Methods Orthokeratology lenses of different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to 28 subjects (median [range] age: 9.3 [7.8–11.0] years). Ocular biometrics were measured weekly for 1 month of lens wear and after lens cessation until the refraction stabilized (mean duration: 2.8 ± 0.4 weeks). Changes between eyes, and the associations between axial shortening and choroidal thickening with other ocular biometrics were analyzed. Results There were no significant between-eye differences in the changes of ocular biometrics (all P > 0.05). After adjusting for paired-eye data, axial length initially decreased by 26 ± 41 μm (P = 0.03) at week 1, then gradually returned to its original length. An approximate antiphase relationship of choroidal thickness (mean change: 9 ± 12 μm, P < 0.001) with axial length was observed. A significant rebound in axial length, but not choroidal thickness, occurred during the cessation period. Central corneal thinning and choroidal thickening accounted for 70% of initial axial shortening. Conclusions Increasing the compression factor by 1.00 D did not affect changes in ocular biometrics in short-term orthokeratology. Significant axial shortening and choroidal thickening were observed during early treatment period. Axial shortening could not be entirely explained by central corneal thinning and choroidal thickening, which warrants further investigation. Translational Relevance Initial axial shortening in orthokeratology is transient and therefore axial length remains useful for long-term monitoring of axial elongation in children.
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Affiliation(s)
- Jason K Lau
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Kin Wan
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Sin-Wan Cheung
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Stephen J Vincent
- Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
| | - Pauline Cho
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
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Hoseini-Yazdi H, Vincent SJ, Collins MJ, Read SA. Regional alterations in human choroidal thickness in response to short-term monocular hemifield myopic defocus. Ophthalmic Physiol Opt 2019; 39:172-182. [PMID: 30950105 DOI: 10.1111/opo.12609] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 03/06/2019] [Indexed: 12/20/2022]
Abstract
PURPOSE To examine the regional changes in human choroidal thickness following short-term exposure to hemifield myopic defocus using optical coherence tomography (OCT). METHODS The central 26˚ visual field of the left eye of 25 healthy young adults (mean age 26 ± 5 years) was exposed to 60 min of clear vision (control session), +3 D full-field, +3 D superior retinal and +3 D inferior retinal myopic defocus, with the right eye occluded. Choroidal thickness across the central 5 mm (17°) macular region was examined before and after 60 min of defocus using a high-resolution, foveal centred vertical OCT line scan, with optical defocus simultaneously imposed using a Badal optometer and cold mirror system mounted on a Spectralis OCT device. RESULTS Averaged across the central 5 mm macular area, choroidal thickness decreased by -4 ± 7 μm during the control session (p = 0.01), most likely due to the unique stimulus conditions of this study. The mean macular choroidal thickness increased during full-field (+2 ± 8 μm), inferior retinal (+3 ± 7 μm) and superior retinal myopic defocus (+5 ± 9 μm), representing a significant thickening of the choroid compared to the control session (all p < 0.05). The defocus induced changes in macular choroidal thickness differed between the superior and inferior hemiretinal regions (F2.26, 54.27 = 29.75, p < 0.001). When only the superior retina was exposed to myopic defocus, the choroid thickened in the superior region (+7 ± 8 μm, p < 0.001), but did not change significantly in the inferior region (+3 ± 9 μm, p = 0.12). When only the inferior retina was exposed to myopic defocus, the choroid thickened inferiorly (+4 ± 8 μm, p = 0.005), with no significant change observed in the superior region (+1 ± 8 μm, p = 0.46). CONCLUSIONS These findings provide evidence supporting a local regional choroidal response to myopic defocus in the human eye, with hemifield myopic defocus leading to significant thickening of the choroid localised to the retinal region exposed to defocus. The novel finding of a localised response of the human choroid to hemifield myopic defocus, particularly in the superior hemiretina, may have important implications in optimising the optical design of myopia control interventions.
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Affiliation(s)
- Hosein Hoseini-Yazdi
- Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
| | - Stephen J Vincent
- Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
| | - Michael J Collins
- Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
| | - Scott A Read
- Contact Lens and Visual Optics Laboratory, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
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16
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Read SA, Fuss JA, Vincent SJ, Collins MJ, Alonso-Caneiro D. Choroidal changes in human myopia: insights from optical coherence tomography imaging. Clin Exp Optom 2018; 102:270-285. [PMID: 30565333 DOI: 10.1111/cxo.12862] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 10/23/2018] [Accepted: 11/12/2018] [Indexed: 01/05/2023] Open
Abstract
The choroid is a vascular tissue which plays a range of critical roles in the normal physiology of the eye, such as supplying the outer retina with oxygen and nutrients and the regulation of intraocular pressure. There is also substantial evidence, particularly from animal studies, that the choroid plays an important role in the regulation of eye growth and the development of common refractive errors like myopia. In recent years, advances in optical coherence tomography technology have improved our ability to image and measure the choroid in the human eye. Research using this technology over the past decade has dramatically improved our knowledge of the normal choroid, and its potential role in the regulation of eye growth and refractive error development. This review aims to provide an overview of recent work examining the normal human choroid, its changes with myopia and the possible role of the choroid in the mechanism regulating eye growth. Studies have demonstrated that choroidal thinning accompanies the development and progression of myopia, and have established a close link between eye growth and choroidal thickness changes. Dramatic thinning of the choroid is seen with high myopia, and associations are also observed between choroidal thinning and reduced vision, and the development of retinal pathology associated with high myopia. In the short-term, environmental factors known to be associated with myopia development and more rapid eye growth typically lead to a thinning of the choroid, whereas factors linked to a slowing of eye growth are typically associated with short-term choroidal thickening. Collectively, these findings suggest that the choroid is an important biomarker of eye growth in the human eye, and additional research to better understand the human choroid is likely to further our knowledge of the signals and pathways regulating eye growth, myopia development and progression.
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Affiliation(s)
- Scott A Read
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Queensland, Australia
| | - James A Fuss
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Stephen J Vincent
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Michael J Collins
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Queensland, Australia
| | - David Alonso-Caneiro
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Queensland, Australia
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17
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Logan N, Guggenheim J, To CH. Myopia: mechanisms, manifestations and management. Ophthalmic Physiol Opt 2018; 38:207-209. [PMID: 29691924 DOI: 10.1111/opo.12461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Nicola Logan
- Ophthalmic Research Group at Aston University, Birmingham, UK
| | - Jez Guggenheim
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, UK
| | - Chi-Ho To
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
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