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Ding C, Mao D, Li X, Huang Y, Hou F, Chen H, Bao J. Peripheral myopic defocus signal affects the efficiency of visual information processing in myopic children. Ophthalmic Physiol Opt 2024; 44:1010-1016. [PMID: 38699881 DOI: 10.1111/opo.13325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 04/19/2024] [Accepted: 04/20/2024] [Indexed: 05/05/2024]
Abstract
PURPOSE Spectacle lenses with peripheral lenslets have shown promise for myopia control by providing peripheral myopic defocus signals. Here, we aimed to investigate the impact of prolonged exposure (>6 months) to peripheral myopic defocus on visual information processing in myopic children. METHODS The study included 30 myopic children who habitually wore spectacle lenses with highly aspherical lenslets (HAL group) and 34 children who habitually wore single-vision (SV group) spectacles. The quick contrast sensitivity function (qCSF) was used to measure contrast sensitivity (CS) under conditions of no or high noise. Both groups were tested with HAL and SV lenses. The perceptual template model was utilised to fit the contrast sensitivity function (CSF) and determine differences in information processing efficiency through internal additive noise (N add ) and perceptual template gain (β). RESULTS The areas under the log CSF in the SV group were significantly higher than for the HAL group in both zero-noise conditions with the SV test lens (p = 0.03) and high-noise conditions with the HAL test lens (p = 0.02). For 2 cycle per degree (cpd) stimuli, β was significantly higher in the SV group with the HAL test lens than in the HAL group (p = 0.02), while there was a trend towards a significant difference in β for 6 cpd stimuli (p = 0.07). However, there were no significant differences inN add between the two groups, with or without noise interference. CONCLUSION The reduced CS observed in myopic children wearing HAL lenses for 6 months or more may be due to decreased β. This suggests that prolonged use of spectacle lenses with peripheral myopic defocus signals may compromise the central visual system's ability to process additional external noise, resulting in decreased efficiency in visual information processing.
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Affiliation(s)
- Chenglu Ding
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Danyi Mao
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Xue Li
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yingying Huang
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Fang Hou
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Hao Chen
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Jinhua Bao
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
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Bang SP, Sabesan R, Yoon G. Effects of Neural Adaptation to Habitual Spherical Aberration on Depth of Focus. RESEARCH SQUARE 2024:rs.3.rs-3917931. [PMID: 38410431 PMCID: PMC10896392 DOI: 10.21203/rs.3.rs-3917931/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
We investigated how long-term visual experience with habitual spherical aberration (SA) influences subjective depth of focus (DoF). Nine healthy cycloplegic eyes with habitual SAs of different signs and magnitudes were enrolled. An adaptive optics (AO) visual simulator was used to measure through-focus high-contrast visual acuity after correcting all monochromatic aberrations and imposing +0.5 μm and -0.5 μm SAs for a 6-mm pupil. The positive (n=6) and negative (n=3) SA groups ranged from 0.17 to 0.8 μm and from -1.2 to -0.12 μm for a 6-mm pupil, respectively. For the positive habitual SA group, the median DoF with positive AO-induced SA (2.18D) was larger than that with negative AO-induced SA (1.91D); for the negative habitual SA group, a smaller DoF was measured with positive AO-induced SA (1.81D) than that with negative AO-induced SA (2.09D). The difference in the DoF of individual participants between the induced positive and negative SA groups showed a quadratic relationship with the habitual SA. Subjective DoF tended to be larger when the induced SA in terms of the sign and magnitude was closer to the participant's habitual SA, suggesting the importance of considering the habitual SA when applying the extended DoF method using optical or surgical procedures.
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Bosten JM, Coen-Cagli R, Franklin A, Solomon SG, Webster MA. Calibrating Vision: Concepts and Questions. Vision Res 2022; 201:108131. [PMID: 37139435 PMCID: PMC10151026 DOI: 10.1016/j.visres.2022.108131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The idea that visual coding and perception are shaped by experience and adjust to changes in the environment or the observer is universally recognized as a cornerstone of visual processing, yet the functions and processes mediating these calibrations remain in many ways poorly understood. In this article we review a number of facets and issues surrounding the general notion of calibration, with a focus on plasticity within the encoding and representational stages of visual processing. These include how many types of calibrations there are - and how we decide; how plasticity for encoding is intertwined with other principles of sensory coding; how it is instantiated at the level of the dynamic networks mediating vision; how it varies with development or between individuals; and the factors that may limit the form or degree of the adjustments. Our goal is to give a small glimpse of an enormous and fundamental dimension of vision, and to point to some of the unresolved questions in our understanding of how and why ongoing calibrations are a pervasive and essential element of vision.
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Affiliation(s)
| | - Ruben Coen-Cagli
- Department of Systems Computational Biology, and Dominick P. Purpura Department of Neuroscience, and Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx NY
| | | | - Samuel G Solomon
- Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, UK
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Huang Y, Li X, Wang C, Zhou F, Yang A, Chen H, Bao J. Visual acuity, near phoria and accommodation in myopic children using spectacle lenses with aspherical lenslets: results from a randomized clinical trial. EYE AND VISION 2022; 9:33. [PMID: 36045391 PMCID: PMC9434851 DOI: 10.1186/s40662-022-00304-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 08/11/2022] [Indexed: 11/10/2022]
Abstract
Abstract
Objectives
To investigate the short- and long-term effects of myopia control spectacle lenses with highly aspherical lenslets (HAL) and slightly aspherical lenslets (SAL) on visual function and visual quality using data obtained from a randomized controlled clinical trial.
Methods
This was a prospective, randomized, controlled, and double-blinded study; 170 myopic children aged 8–13 years were randomly assigned to the HAL, SAL, or single-vision spectacle lenses (SVL) groups. Distance and near visual acuity (VA) at high (100%) and low (10%) contrast in photopic and scotopic conditions, near phoria, stereoacuity, and accommodative lag, microfluctuations (AMFs), amplitude (AA) were measured after wearing lenses for 10 min, 6 months, and 12 months.
Results
In total, 161 subjects completed all follow-up in 12 months and were included in the analysis. After 10 min of wearing, the HAL and SAL groups had lower scotopic and low-contrast VA than the SVL group (decreased 0.03–0.08 logMAR and 0.01–0.04 logMAR in different VAs in the HAL and SAL groups, respectively, all P < 0.05). The reduction in VA was recovered at 12 months as the HAL and SAL groups exhibited significant VA improvements, and the VA was not different among the three groups (all P > 0.05). The HAL and SAL groups had significantly larger AMFs than the SVL group (HAL vs. SAL vs. SVL: 0.21 ± 0.08 D vs. 0.16 ± 0.05 D vs. 0.15 ± 0.06 D at baseline, 0.19 ± 0.07 D vs. 0.17 ± 0.05 D vs. 0.13 ± 0.07 D at 12 months, all P < 0.05). There were no significant differences in accommodative lag, AA, or phoria between the groups (all P > 0.05). The HAL and SAL groups had reduced stereoacuity compared to the SVL group at baseline (70’ vs. 60’ vs. 50’, P = 0.005), but no difference was observed at 12 months (70’ vs. 70’ vs. 70’, P = 0.11).
Conclusions
HAL and SAL have no significant influence on accommodation and phoria except had larger AMF than SVL. Scotopic VA and low-contrast VA are reduced with short-term HAL and SAL use but recovered to be at same level with the SVL after 1 year of use.
Trial registration Chinese Clinical Trial Registry: ChiCTR1800017683. Registered on 9 August 2018. http://www.chictr.org.cn/showproj.aspx?proj=29789
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The role of retinotopic cues in deciphering the direction and magnitude of monocular dynamic ocular accommodation: A review. Vision Res 2022; 196:108026. [DOI: 10.1016/j.visres.2022.108026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 02/04/2022] [Accepted: 02/10/2022] [Indexed: 12/28/2022]
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Variability of Accommodative Microfluctuations in Myopic and Emmetropic Juveniles during Sustained near Work. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19127066. [PMID: 35742313 PMCID: PMC9222619 DOI: 10.3390/ijerph19127066] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/31/2022] [Accepted: 06/06/2022] [Indexed: 11/26/2022]
Abstract
Near work has been considered to be a potential risk factor for the onset of myopia, but with inadequate evidence. Chinese adolescents use digital devices for near work, such as study and entertainment purposes, especially during the COVID-19 pandemic. In this study, we investigated the influence of prolonged periods of near work on accommodative response, accommodative microfluctuations (AMFs), and pupil diameter between juvenile subjects of myopia and emmetropia. Sixty juveniles (30 myopes and 30 emmetropes) were recruited for the study. Participants were instructed to play a video game on a tablet PC at a distance of 33.3 cm for 40 min. Accommodative response and pupil diameter were measured with an open-field infrared refractometer in High-speed mode. Parameters of the subjects were measured once every 10 min, and analyzed by one-way repeated measure ANOVA for variation tendency. There were no significant differences between emmetropia and myopia groups with respect to age and sex (p > 0.05). The low-frequency component (LFC) of myopia gradually increased with time, reached a peak at 30 min, and then declined (p = 0.043). The high-frequency component (HFC) of myopia also reached a peak at 30 min (p = 0.036). Nevertheless, there was no significant difference in the LFC (p = 0.171) or HFC (p = 0.278) of the emmetropia group at each time point. There was no significant difference in the mean and standard deviation of the accommodative response and pupil diameter both in emmetropic and myopic juveniles. Compared with juvenile emmetropes, myopes exhibit an unstable tendency in their accommodation system for prolonged near work at a certain time point. Accommodative microfluctuations may be a sensitive, objective indicator of fatigue under sustained near work in juvenile myopes.
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Effects of Customized Progressive Addition Lenses vs. Single Vision Lenses on Myopia Progression in Children with Esophoria: A Randomized Clinical Trial. J Ophthalmol 2022; 2022:9972761. [PMID: 35265370 PMCID: PMC8898881 DOI: 10.1155/2022/9972761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 02/08/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose To evaluate the effect of customized progressive addition lenses (CPALs) versus single vision lenses (SVLs) on the progression of juvenile-onset myopia in children with near esophoria. Methods Ninety-three Chinese children, aged 7–14 years with spherical equivalent refraction (SER) ranging from −0.50 to −4.00 D and near esophoria ≥2Δ, were randomly assigned into a CPALs (n = 46) and an SVLs group (n = 47) for a 2-year, double-masked, randomized trial. The primary outcome measure was the progression of myopia, as determined by cycloplegic autorefraction. A customized near addition, calculated by a regression equation, was prescribed to establish a fixed heterophoria status for each child, which was −3Δ exophoria. Results Eighty-four (90.3%) of the 93 children completed the 2-year follow-up. The mean initial near addition lenses were 1.65 ± 0.07 D (mean ± SE). The adjusted 2-year myopia progression was 0.23 ± 0.08 D slower in the CPALs group than in the SVLs group (p=0.046). Post hoc analysis found significantly larger treatment effects for CPALs in children without myopic parents (0.47 ± 0.15 D; 95% CI: 0.18–0.76), with lower baseline myopia (0.33 ± 0.09 D; 95% CI: 0.14–0.52; p < 0.05), with higher baseline accommodative lag (0.36 ± 0.11 D; 95% CI: 0.12–0.60; p < 0.05), and with higher baseline near esophoria (0.30 ± 0.10 D; 95% CI: 0.12–0.48; p < 0.05). Conclusion CPALs exerted a significant but minimal protective effect against myopia progression in Chinese children with esophoric myopia, as compared with SVLs. Regulating near heterophoria and accommodative lag by near addition lenses may not be an appropriate way to prevent myopia progression.
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Hughes A, Fylan F, Elliott DB. What are patients' beliefs about, and experiences of, adaptation to glasses and how does this affect their wearing habits? Ophthalmic Physiol Opt 2021; 41:1034-1047. [PMID: 34405421 DOI: 10.1111/opo.12867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/25/2021] [Accepted: 06/28/2021] [Indexed: 11/28/2022]
Abstract
PURPOSE It is well known that some patients experience difficulties adapting to new glasses. However, little is known about what patients themselves understand of the adaptation process, and how this influences their attitudes and the decisions they make when adapting to a new pair of glasses. Nor is it understood whether these factors affect their wearing habits. METHODS We conducted four focus groups. Participants were 22 glasses wearers (mean ± SD age 43 ± 14 years, range 21-71 years) who reported they: (1) wore spectacle correction for distance vision (single vision, bifocal or progressive lenses); (2) had struggled to get used to a new pair of glasses and (3) sometimes chose not to wear their distance correction. Focus groups were audio recorded, transcribed verbatim and analysed thematically. RESULTS We identified three themes. Trust is about how participants' trust in their optometrist and themselves influences the likelihood of them adapting successfully to new glasses. Conflict describes how the advice patients have received about adapting to glasses can conflict with what they have experienced and how this conflict influences their expectations. Part of Me explores how participants' experiences and feelings about their glasses are important to adaptation and this includes physical, visual, emotional and behavioural aspects. CONCLUSIONS The traditional optometric perspective of adaptation to glasses is much narrower than that held by patients, and significantly underestimates the physical, behavioural and emotional adaptation that patients must go through in order to feel fully comfortable wearing their glasses. Patients should receive significantly more information about adaptation, including symptoms that may be experienced and why these happen, practical tips to aid adaptation, and when and how to raise concerns. Patients should also receive information about the day-to-day effects of blur adaptation to avoid them not wearing their glasses, including for vision-critical tasks such as driving.
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Affiliation(s)
- Amy Hughes
- Bradford School of Optometry and Vision Science, University of Bradford, Bradford, UK
| | - Fiona Fylan
- Brainbox Research, Leeds, UK.,Leeds Sustainability Institute, Leeds Beckett University, Leeds, UK
| | - David B Elliott
- Bradford School of Optometry and Vision Science, University of Bradford, Bradford, UK
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Abstract
Myopes exhibit a larger capability of adaptation to defocus. Adaptation produces a boost in visual performance that can be characterized through different metrics. The ability of myopes to adapt to other sources of blur, such as diffusion, has not been studied so far. In this work, a group of 20 myopes with normal vision underwent high-contrast visual acuity (VA) measurements under different viewing conditions, wearing their refractive correction with or without a diffuser (Bangerter filter, BF). VA decreased immediately after wearing the BF of density 0.6, showing a significant relationship with the ocular refraction. After 40 minutes of binocular vision through the BF, a statistically significant increase (p = 0.02) in VA from 0.54 to 0.62 in decimal scale (from 0.3 to 0.2 logMAR) was obtained. No correlation with the refraction was observed. After removing the diffuser, VA returned to baseline. A control group (17 subjects) underwent the same experimental protocol but without diffuser filters. No significant changes in VA were found in this group. We describe a new type of contrast adaptation to blur in myopes caused by scattering, rather than by defocus. The effects of low scattering levels in vision might be relevant in the analysis of early stage of cataract, amblyopia treatments, and myopia understanding.
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10
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Wood JM, Chiu C, Kim GH, Le J, Lee HJ, Nguyen T, Black AA. Refractive blur affects judgement of pedestrian walking direction at night. Ophthalmic Physiol Opt 2021; 41:582-590. [DOI: 10.1111/opo.12811] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 02/21/2021] [Accepted: 02/21/2021] [Indexed: 11/29/2022]
Affiliation(s)
- Joanne M Wood
- Centre for Vision and Eye Research School of Optometry and Vision Science Queensland University of Technology Brisbane Queensland Australia
| | - Chiau‐Ni Chiu
- Centre for Vision and Eye Research School of Optometry and Vision Science Queensland University of Technology Brisbane Queensland Australia
| | - Gie Hee Kim
- Centre for Vision and Eye Research School of Optometry and Vision Science Queensland University of Technology Brisbane Queensland Australia
| | - Jenny Le
- Centre for Vision and Eye Research School of Optometry and Vision Science Queensland University of Technology Brisbane Queensland Australia
| | - Hyun Jung Lee
- Centre for Vision and Eye Research School of Optometry and Vision Science Queensland University of Technology Brisbane Queensland Australia
| | - Tien Nguyen
- Centre for Vision and Eye Research School of Optometry and Vision Science Queensland University of Technology Brisbane Queensland Australia
| | - Alex A Black
- Centre for Vision and Eye Research School of Optometry and Vision Science Queensland University of Technology Brisbane Queensland Australia
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11
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Xu J, Tao C, Mao X, Lu X, Bao J, Drobe B, Chen H. Blur Detection Sensitivity Increases in Children Using Orthokeratology. Front Neurosci 2021; 15:630844. [PMID: 33790734 PMCID: PMC8006440 DOI: 10.3389/fnins.2021.630844] [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: 11/18/2020] [Accepted: 02/24/2021] [Indexed: 11/29/2022] Open
Abstract
Purpose To investigate changes in blur detection sensitivity in children using orthokeratology (Ortho-K) and explore the relationships between blur detection thresholds (BDTs) and aberrations and accommodative function. Methods Thirty-two children aged 8–14 years old who underwent Ortho-K treatment participated in and completed this study. Their BDTs, aberrations, and accommodative responses (ARs) were measured before and after a month of Ortho-K treatment. A two forced-choice double-staircase procedure with varying extents of blur in three images (Tumbling Es, Lena, and Street View) was used to measure the BDTs. The participants were required to judge whether the images looked blurry. The BDT of each of the images (BDT_Es, BDT_Lena, and BDT_Street) was the average value of the last three reversals. The accommodative lag was quantified by the difference between the AR and the accommodative demand (AD). Changes in the BDTs, aberrations, and accommodative lags and their relationships were analyzed. Results After a month of wearing Ortho-K lenses, the children’s BDT_Es and BDT_Lena values decreased, the aberrations increased significantly (for all, P ≤0.050), and the accommodative lag decreased to a certain extent [T(31) = 2.029, P = 0.051]. Before Ortho-K treatment, higher-order aberrations (HOAs) were related to BDT_Lena (r = 0.463, P = 0.008) and the accommodative lag was related to BDT_Es (r = −0.356, P = −0.046). After one month, no significant correlations were found between the BDTs and aberrations or accommodative lags, as well as between the variations of them (for all, P ≥ 0.069). Conclusion Ortho-K treatment increased the children’s level of blur detection sensitivity, which may have contributed to their good visual acuity.
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Affiliation(s)
- Jingjing Xu
- School of Ophthalmology and Optometry, Affiliated Eye Hospital, State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China.,WEIRC, Wenzhou Medical University-Essilor International Research Center, Wenzhou, China
| | - Chunwen Tao
- School of Ophthalmology and Optometry, Affiliated Eye Hospital, State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Xinjie Mao
- School of Ophthalmology and Optometry, Affiliated Eye Hospital, State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China.,WEIRC, Wenzhou Medical University-Essilor International Research Center, Wenzhou, China
| | - Xin Lu
- School of Ophthalmology and Optometry, Affiliated Eye Hospital, State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Jinhua Bao
- School of Ophthalmology and Optometry, Affiliated Eye Hospital, State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China.,WEIRC, Wenzhou Medical University-Essilor International Research Center, Wenzhou, China
| | - Björn Drobe
- WEIRC, Wenzhou Medical University-Essilor International Research Center, Wenzhou, China.,R&D AMERA, Essilor International, Singapore, Singapore
| | - Hao Chen
- School of Ophthalmology and Optometry, Affiliated Eye Hospital, State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China.,WEIRC, Wenzhou Medical University-Essilor International Research Center, Wenzhou, China
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Hoseini-Yazdi H, Vincent SJ, Read SA, Collins MJ. Astigmatic Defocus Leads to Short-Term Changes in Human Choroidal Thickness. Invest Ophthalmol Vis Sci 2021; 61:48. [PMID: 32729913 PMCID: PMC7425733 DOI: 10.1167/iovs.61.8.48] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To examine the choroidal thickness (ChT) response to short-term with-the-rule (WTR) and against-the-rule (ATR) simple myopic astigmatic defocus, with the response to spherical myopic defocus and clear vision used as control conditions. Methods The left eye of 18 healthy adults aged 28 ± 6 years was exposed to clear vision, +3 D spherical myopic defocus, +3 D × 180 WTR, or +3 D × 90 ATR astigmatic defocus for 60 minutes, over four randomly ordered visits, while their right eye was optimally corrected. The macular ChT was measured with optical coherence tomography along the vertical and horizontal meridians before and after 20, 40, and 60 minutes of defocus. Results After 60 minutes of defocus, ChT increased by +8 ± 5 µm (P < 0.001) with spherical myopic defocus, but varied with simple myopic astigmatic defocus, depending on the axis of astigmatism (P < 0.001), increasing by +5 ± 6 µm (P = 0.037) with WTR and decreasing by −4 ± 5 µm (P = 0.011) with ATR astigmatic defocus. These changes were similar across the vertical and horizontal meridians (P = 0.22). The ChT changes were greater than the change during the clear vision control condition (−1 ± 4 µm) for WTR (+5 ± 5 µm, P = 0.002) but not ATR (−4 ± 6 µm, P = 0.09) astigmatic defocus. Conclusions These results provide insights into the human ChT response to short-term astigmatic defocus and highlight a potential difference in the myopiagenic signal associated with the orientation of astigmatic blur.
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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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14
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Accommodation responses following contrast adaptation. Vision Res 2020; 170:12-17. [PMID: 32217367 DOI: 10.1016/j.visres.2020.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/03/2020] [Accepted: 03/03/2020] [Indexed: 11/21/2022]
Abstract
The current study explored the effects of contrast adaptation on the accommodation response (AR), using low- and high-pass filtered video clips as stimuli. Ten young myopic (mean ± standard deviation: -2.91 ± 1.36D) and 10 near emmetropic subjects (-0.19 ± 0.14D) participated in the study. The AR was monitored under monocular viewing conditions using an eccentric infrared photorefractor. A 2-stage procedure was used: (1) the minimum spatial frequency content necessary to produce a proper individual AR; and (2) the AR was compared before and after adaptation to low-pass (s = -0.5), control (s = 0) and high-pass (s = +0.5) filtered videos. We found that (1) the average threshold Sinc-blur of both myopes and emmetropes necessary to evoke accommodation was (mean ± standard deviation) λ = 7.40 ± 4.05 cpd. Myopes required a higher Sinc blur (average, 10.00 ± 4.05 cpd) compared to emmetropes (average, 4.80 ± 1.60 cpd). (2) Adaptation to low-pass filtered videos increased the AR by 0.41 ± 0.33D in the myopic group and reduced it in the emmetropic group by 0.31 ± 0.25D. Adaptation to high pass-filtered videos induced similar changes in both refractive groups (an increase of 0.41 ± 0.40D and 0.46 ± 0.29D for myopes and emmetropes, respectively). Our measurements show that the human AR can be modified by spatial frequency selective contrast adaptation although these were short-term effects. The perhaps most striking finding was that adaptation to low pass filtered videos had opposite effects on the AR in emmetropes and myopes. It remains to be studied whether these differences were a consequence of myopia or a contributing factor in myopia development.
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15
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Cufflin MP, Mallen EA. Blur adaptation: clinical and refractive considerations. Clin Exp Optom 2019; 103:104-111. [PMID: 31801179 DOI: 10.1111/cxo.13033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/08/2019] [Accepted: 11/13/2019] [Indexed: 01/28/2023] Open
Abstract
The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed.
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Affiliation(s)
- Matthew P Cufflin
- School of Optometry and Vision Science, University of Bradford, Bradford, West Yorkshire, UK
| | - Edward Ah Mallen
- School of Optometry and Vision Science, University of Bradford, Bradford, West Yorkshire, UK
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Durmus D, Davis W. Blur perception and visual clarity in light projection systems. OPTICS EXPRESS 2019; 27:A216-A223. [PMID: 30876137 DOI: 10.1364/oe.27.00a216] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/31/2019] [Indexed: 06/09/2023]
Abstract
Previous studies proposed a smart lighting system that can detect object colors and emit spectrally optimized lighting to reduce the light absorbed by surfaces. The spatial resolution of an absorption-minimization light projection system is investigated using images of various visual complexity. Participants with normal color vision and good visual acuity judged the visual clarity of low, medium, and high complexity images by using a mean opinion score (MOS) scale. Results from the visual assessments show that blur acceptability of illuminated images significantly reduces when the circle of confusion (CoC) is increased by 3%. Blur perception also changes with visual complexity.
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Labhishetty V, Chakraborty A, Bobier WR. Is blur sensitivity altered in children with progressive myopia? Vision Res 2018; 154:142-153. [PMID: 30472331 DOI: 10.1016/j.visres.2018.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 11/07/2018] [Accepted: 11/13/2018] [Indexed: 12/25/2022]
Abstract
School aged children with progressive myopia show large accommodative lags to blur only cue which is suggestive of a large depth of focus (DOF). While DOF measures are lacking in this age group, their blur detection and discrimination capacities appear to be similar to their non-myopic peers. Accordingly, the current study quantified DOF and blur detection ability in progressive myopic children showing large accommodative lags compared to their non-myopic peers and adults. Blur sensitivity measures were taken from 12 children (8-13 years, 6 myopes and 6 emmetropes) and 6 adults (20-35 years). DOF was quantified using step changes in the lens induced defocus while the subjects viewed a high contrast target through a Badal lens at either 2 or 4D demand. Blur detection thresholds (BDT) were tested using a similar high contrast target in a 2-alternate forced-choice paradigm (2AFC) at both the demands. In addition to the large accommodative lags, micro fluctuations and DOF were significantly larger in myopic children compared to the other groups. However, BDTs were similar across the three groups. When limited to blur cues, the findings of a large DOF coupled with large response lags suggests that myopes are less sensitive to retinal defocus. However, in agreement to a previous study, refractive error had no influence on their BDTs suggesting that the reduced sensitivity to the defocus in a myopic eye appears to be compensated by some form of an adjustment in the higher visual processes to preserve the subjective percept even with a poor retinal image quality.
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Affiliation(s)
- Vivek Labhishetty
- School of Optometry and Vision Science, University of Waterloo, Waterloo, ON N2L3G1, Canada.
| | - Arijit Chakraborty
- School of Optometry and Vision Science, University of Waterloo, Waterloo, ON N2L3G1, Canada
| | - William R Bobier
- School of Optometry and Vision Science, University of Waterloo, Waterloo, ON N2L3G1, Canada
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Reduced amblyopic eye fixation stability cannot be simulated using retinal-defocus-induced reductions in visual acuity. Vision Res 2018; 154:14-20. [PMID: 30389388 DOI: 10.1016/j.visres.2018.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 10/05/2018] [Accepted: 10/23/2018] [Indexed: 11/23/2022]
Abstract
Amblyopia is associated with impaired visual acuity (VA) and reduced fixation stability (FS). To assess whether impaired VA may cause reduced FS, the effects of retinal-defocus-induced visual acuity reductions on FS were measured in observers with amblyopia and controls. Fixational eye movements were measured in 8 patients with amblyopia and 12 controls. Monocular near VA of a subset of controls (n = 5) was then varied from 20/20 to 20/100 using convex lenses. The amblyopia group completed three monocular conditions; 1) amblyopic eye fixating, 2) fellow eye fixating and 3) fellow eye fixating with VA reduced to match the amblyopic eye. Fixational eye movements were quantified using bivariate contour ellipse area (BCEA) and microsaccadic amplitude. Amblyopic eye BCEA was significantly larger with increased microsaccadic amplitude compared to the fellow eye and control eyes. BCEA and VA were positively correlated for amblyopic eyes. VA impairments induced by retinal defocus did not reduce FS in controls or the fellow eye of observers with amblyopia, even when fellow eye VA was matched to that of the amblyopic eye. This suggests that reduced FS in amblyopic eyes cannot be simulated by acute VA reductions. Therefore, reduced amblyopic eye FS may not be a direct consequence of the VA loss alone. As in previous studies, a correlation between BCEA and VA for amblyopic eyes was observed. This relationship could be due to a third, mediating variable or an effect of fixational eye movements on VA.
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Zapata-Díaz JF, Marín-Franch I, Radhakrishnan H, López-Gil N. Impact of higher-order aberrations on depth-of-field. J Vis 2018; 18:5. [PMID: 30458513 DOI: 10.1167/18.12.5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
It is well known that depth-of-focus (DOF) is influenced by optical factors (such as pupil size and monochromatic aberrations). However, neural factors such as blur sensitivity and defocus adaptation may play an important role on the extent of DOF. A series of experiments were conducted to study if optical or neural factors are most pertinent in explaining the variability of DOF across subjects. An adaptive optics system with a black and white target, a 3.8-mm artificial pupil, and a subjective criterion (based on objectionable blur) were used to measure depth of field ([DOFi]; DOF computed in the object space) in 11 participants, after at least 6 min of adaptation. This was done under three conditions: (a) with their own higher order aberrations (HOA); (b) after correction of their monochromatic HOA; and (c) after altering the HOA pattern for some participants to reflect the HOA pattern measured for a different participant. Natural DOFi and DOFi after HOA correction were positively correlated (R2 = 0.461), but a significant decrease in DOFi (21% on average) was found after HOA correction (p = 0.042). Effect of HOA on the intersubject variability of DOFi was 3.9 times smaller than the effect of the image neural processing. This study shows that DOFi depends on both optical and neural factors, but the latter seems to play a more important role than the former.
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Affiliation(s)
- Juan F Zapata-Díaz
- Grupo de Investigación en Ciencias de la Visión, Universidad de Murcia, Murcia, Spain.,Faculty of Biology, Medicine & Health, The University of Manchester, Manchester Academic Health Science Center, Manchester, UK
| | - Iván Marín-Franch
- Grupo de Investigación en Ciencias de la Visión, Universidad de Murcia, Murcia, Spain.,Department of Ophthalmology and Vision Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hema Radhakrishnan
- Faculty of Biology, Medicine & Health, The University of Manchester, Manchester Academic Health Science Center, Manchester, UK
| | - Norberto López-Gil
- Grupo de Investigación en Ciencias de la Visión, Universidad de Murcia, Murcia, Spain
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Abstract
PURPOSE To examine the effects of optical blur, auditory distractors, and age on eye movement patterns while performing a driving hazard perception test (HPT). METHODS Twenty young (mean age 27.1 ± 4.6 years) and 20 older (73.3 ± 5.7 years) drivers with normal vision completed a HPT in a repeated-measures counterbalanced design while their eye movements were recorded. Testing was performed under two visual (best-corrected vision and with +2.00DS blur) and two distractor (with and without auditory distraction) conditions. Participants were required to respond to road hazards appearing in the HPT videos of real-world driving scenes and their hazard response times were recorded. RESULTS Blur and distractors each significantly delayed hazard response time by 0.42 and 0.76 s, respectively (p < 0.05). A significant interaction between age and distractors indicated that older drivers were more affected by distractors than young drivers (response with distractors delayed by 0.96 and 0.60 s, respectively). There were no other two- or three-way interaction effects on response time. With blur, for example, both groups fixated significantly longer on hazards before responding compared to best-corrected vision. In the presence of distractors, both groups exhibited delayed first fixation on the hazards and spent less time fixating on the hazards. There were also significant differences in eye movement characteristics between groups, where older drivers exhibited smaller saccades, delayed first fixation on hazards, and shorter fixation duration on hazards compared to the young drivers. CONCLUSIONS Collectively, the findings of delayed hazard response times and alterations in eye movement patterns with blur and distractors provide further evidence that visual impairment and distractors are independently detrimental to driving safety given that delayed hazard response times are linked to increased crash risk.
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Neural adaptation to peripheral blur in myopes and emmetropes. Vision Res 2016; 132:69-77. [PMID: 27919674 DOI: 10.1016/j.visres.2016.09.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/30/2016] [Accepted: 09/23/2016] [Indexed: 11/20/2022]
Abstract
In the presence of optical blur at the fovea, blur adaptation can improve visual acuity (VA) and perceived image quality over time. However, little is known regarding blur adaptation in the peripheral retina. Here, we examined neural adaptation to myopic defocus at the fovea and parafovea (10° temporal retina) in both emmetropes and myopes. During a 60-min adaptation period, subjects (3 emmetropes and 3 myopes) watched movies with +2 diopters of defocus blur through a 6-mm artificial pupil in two separate, counter-balanced sessions for each retinal location. VA was measured at 10-min intervals under full aberration-corrected viewing using an adaptive optics (AO) vision simulator. By correcting subjects' native optical aberrations with AO, we bypassed the influence of the individual subjects' optical aberrations on visual performance. Overall, exhibited a small but significant improvement after the 60-min of adaptation at both the fovea (mean±SE VA improvement: -0.06±0.04 logMAR) and parafovea (mean±SE VA improvement: -0.07±0.04 logMAR). Myopic subjects exhibited significantly greater improvement in parafoveal VA (mean±SE VA improvement: 0.10±0.02 logMAR), than that of emmetropic subjects (mean±SE VA improvement: 0.04±0.03 logMAR). In contrast, there was no significant difference in foveal VA between the two refractive-error groups. In conclusion, our results reveal differences in peripheral blur adaptation between refractive-error groups, with myopes displaying a greater degree of adaptation.
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Khan KA, Cufflin MP, Mallen EAH. The effect of interrupted defocus on blur adaptation. Ophthalmic Physiol Opt 2016; 36:649-656. [PMID: 27790776 DOI: 10.1111/opo.12323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 08/25/2016] [Indexed: 01/22/2023]
Abstract
PURPOSE Blur adaptation occurs when an observer is exposed to continuous defocus. However, it is unclear whether adaptation requires constant defocus, or whether the effect can still be achieved when the adaptation period is interrupted by short periods of clear vision. METHODS The study included 12 emmetropes and 12 myopes. All observers wore full refractive correction throughout the experiment. 1D and 3D of myopic defocus was introduced using spherical convex lenses. An automated system was used to place the blurring lens before the RE for varying periods of blurred and clear vision during adaptation. Participants watched a DVD at 3 m during each 15 min trial. Visual acuity was measured using Test Chart 2000 before and after adaptation. RESULTS Blur adaptation occurs to varying degrees depending on the periods of incremental blur exposure. Significant improvements in defocused visual acuity occur with continuous blur, equal blur and clear periods, as well as for longer blur periods. However, longer clear periods showed reduced adaptation and this trial is significantly different to the other three trials for both defocus levels (p < 0.001). No refractive group differences were observed for neither 1D nor 3D defocus (p = 0.58 and p = 0.19 respectively). CONCLUSIONS Intervening periods of clear vision cause minimal disruption to improvements in defocused visual acuity after adaptation, indicating that blur adaptation is a robust phenomenon. However, when the exposure to clear vision exceeds the defocused periods, adaptation is inhibited. This gives insight into the effects of real-world tasks on adaptation to blur.
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Affiliation(s)
- Kiren A Khan
- School of Optometry and Vision Science, University of Bradford, Bradford, UK
| | - Matthew P Cufflin
- School of Optometry and Vision Science, University of Bradford, Bradford, UK
| | - Edward A H Mallen
- School of Optometry and Vision Science, University of Bradford, Bradford, UK.
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Vasudevan B, Sultani K, Cossette C, Burr B. Effect of defocus on response time in different age groups: A pilot study. JOURNAL OF OPTOMETRY 2016; 9:196-202. [PMID: 26749188 PMCID: PMC4911444 DOI: 10.1016/j.optom.2015.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 11/13/2015] [Accepted: 11/18/2015] [Indexed: 06/05/2023]
Abstract
PURPOSE To assess the response time associated with visual performance (VP) tasks in the presence of defocus in different presbyopic populations. METHODS 58 eyes between the ages of 35 and 50 years were studied. Subjects were categorized as pre-presbyopic (35-39 years), early-presbyopic (40-45 years), and mid-presbyopic (46-50 years). VP measurements obtained monocularly included distance and near high contrast (HC) and low contrast (LC) optotype recognition, and contrast threshold at 12cpd for different defocus magnitudes between 0D and 3D in 1D steps. Response time defined as the time taken to recognize and verbalize an optotype, was compared among different presbyopic age groups. RESULTS From 58 eyes, mean (SD) response time for high contrast distance visual acuity for 0D through 3D ranged between 1.48 (0.23) and 1.87 (0.31)s, whereas low contrast distance visual acuity ranged between 1.5 (0.22) and 2.09 (0.49)s. Mean response time for high contrast near visual acuity for 0D through 3D ranged between 1.56 (0.19) and 2.23 (0.45)s. However, for low contrast near visual acuity it ranged between 1.75 (0.32) and 2.71 (0.94)s. Mean (SD) response time for 12cpd ranged between 2.11 (0.50) and 5.72 (1.09)s. ANOVA revealed a significant difference in response time for distance, near visual acuity and contrast sensitivity as a function of defocus for different age groups. CONCLUSIONS Response time is increased in the presence of increasing defocus for both distance and near visual acuity and could impact on performance for critical tasks. Full correction of visual acuity at distance and near in presbyopes is warranted always.
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Affiliation(s)
| | - Kaiser Sultani
- College of Optometry, Midwestern University, Glendale, AZ 85308, USA
| | | | - Brandon Burr
- College of Optometry, Midwestern University, Glendale, AZ 85308, USA
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Affiliation(s)
- W Neil Charman
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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Comparison of visual field progression between temporally tilted disc and nontilted disc, in patients with normal tension glaucoma. Eye (Lond) 2015; 29:1308-14. [PMID: 25721518 DOI: 10.1038/eye.2015.17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 01/01/2015] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To investigate the long-term visual field (VF) progression of temporally tilted disc and nontilted disc in normal tension glaucoma (NTG). METHODS Retrospective, observational case series. Forty-seven patients with temporally tilted disc (47 eyes), 44 patients with nontilted disc in NTG (44 eyes) patients, who were examined by at least 5 VF tests, and were followed-up over a 5-year period, at the Department of Ophthalmology of the Samsung Medical Center, from May 1998 to 2013. VF progression was defined by modified Anderson-Hodapp criteria, and Glaucoma Progression Analysis (GPA). Multivariate analysis was used to identify the risk factors for VF progression in the temporally tilted disc. RESULTS According to the Anderson-Hodapp criteria, progression rates of the temporally tilted disc and nontilted disc at 60 months were 19% and 72%, respectively (P<0.0001). According to GPA, they were 25% and 53%, respectively (P<0.0001). Twenty of 47 patients in the temporally tilted disc did not show progression. Among them, the more tilted disc showed the more VF defects. The hazard ratio of retinal nerve fiber layer (RNFL) defect type was 3.08 (95% CI, 1.17-8.14; P=0.02). The simultaneous superior and inferior RNFL defect type was the most common in progressors in the temporally tilted disc (P=0.04). CONCLUSION Through long-term follow-up, the cumulative survival rate of temporally tilted disc was higher than that of nontilted disc. Caution is required in the treatment of the temporally tilted disc. New treatment policy for the temporally tilted disc may follow.
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Westheimer G. Can perceptual learning compensate for optical image blur? Vision Res 2014; 94:58-61. [DOI: 10.1016/j.visres.2013.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/05/2013] [Accepted: 11/09/2013] [Indexed: 11/24/2022]
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