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Gupta P, Murray JM, Beylergil SB, Jacobs J, Kilbane CW, Shaikh AG, Ghasia FF. Objective assessment of eye alignment and disparity-driven vergence in Parkinson's disease. Front Aging Neurosci 2023; 15:1217765. [PMID: 38020777 PMCID: PMC10643751 DOI: 10.3389/fnagi.2023.1217765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 10/05/2023] [Indexed: 12/01/2023] Open
Abstract
Background Self-reported diplopia is described in up to one-third of Parkinson's disease (PD) patients. Objective The purpose of our study was to expand our understanding of the mechanistic underpinnings of diplopia in PD. We hypothesize that the time-based control of eye alignment and increased eye deviation under binocular viewing will be related to the fusion-initiating and fusion-maintaining component deficits of disparity-driven vergence in PD. Methods We used high-resolution video-oculography to measure eye alignment under binocular and monocular viewing and disparity-driven vergence in 33 PD and 10 age-matched healthy participants. We computed eye deviation and time-based control of eye alignment, occurrence of conjugate saccadic eye movements, latency and gain of vergence (fusion initiation), and variance of eye position at the end of dynamic vergence (fusion maintenance). Results We categorized PD subjects into three groups, considering their time-based control of eye alignment as compared to healthy controls in binocular viewing. Group 1 = 45% had good control and spent >80% of the time when the eyes were well-aligned, Group 2 = 26% had intermediate control and spent <80% but greater >5% of the time when the eyes were well-aligned, and Group 3 = 29% had very poor control with increased eye deviation majority of the times (<5% of the time when the eyes were well-aligned). All three groups exhibited greater eye deviation under monocular viewing than controls. PD subjects exhibited fusion-initiating and fusion-maintaining vergence deficits (prolonged latencies, reduced vergence gain, increased variance of fusion-maintaining component) with a greater probability of saccadic movements than controls. Group 2 and Group 3 subjects were more likely to exhibit failure to initiate vergence (>20%) than Group 1 (13%) and controls (0%) trials. No significant difference was found in the Unified Parkinson's Disease Rating Scale (UPDRS-a tool to measure the severity of PD) values between the three PD groups (Group 1 = 33.69 ± 14.22, Group 2 = 38.43 ± 22.61, and Group 3 = 23.44 ± 1, p > 0.05). Conclusion The majority of PD subjects within our cohort had binocular dysfunction with increased eye deviation under monocular viewing and disparity-driven vergence deficits. PD subjects with intermediate or poor control of eye deviation under binocular viewing had greater fusion-initiating and fusion-maintaining vergence deficits. The study highlights the importance of assessing binocular dysfunction in PD subjects independent of the severity of motor symptoms.
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Affiliation(s)
- Palak Gupta
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Daroff-Dell’Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, OH, United States
| | - Jordan M. Murray
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Sinem Balta Beylergil
- Daroff-Dell’Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, OH, United States
| | - Jonathan Jacobs
- Daroff-Dell’Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, OH, United States
| | - Camilla W. Kilbane
- Department of Neurology, University Hospitals, Cleveland, OH, United States
| | - Aasef G. Shaikh
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Daroff-Dell’Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, OH, United States
- Department of Neurology, University Hospitals, Cleveland, OH, United States
- Neurology Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States
| | - Fatema F. Ghasia
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Daroff-Dell’Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, OH, United States
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Defocus curves: Focusing on factors influencing assessment. J Cataract Refract Surg 2022; 48:961-968. [PMID: 35137697 DOI: 10.1097/j.jcrs.0000000000000906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 02/01/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT Defocus curve assessment is used to emulate defocus over a range of distances and is a valuable tool that is used to differentiate the performance of presbyopia-correcting intraocular lenses. However, defocus curves are limited by a lack of standardization, and multiple factors can impact their generation and interpretation. This review discusses key factors that influence the assessment of defocus curves, including pupil size, level of contrast, sphere versus cylinder defocus, viewing distance, monocular versus binocular assessment, use of Snellen versus logarithm of the minimum angle of resolution charts, and diopter range and step size. There are also different methods to analyze defocus curves, including the direct comparison method, range-of-focus analysis, and area under the curve analysis, which can impact result interpretation. A good understanding of these factors and standardization of the methodology are important to ensure optimal cross-study comparisons.
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Akbari MR, Heirani M, Kundart J, Christian L, Khorrami-Nejad M, Masoomian B. Application of bifocal and progressive addition lenses in the management of accommodative esotropia: A comprehensive review of current practices. Surv Ophthalmol 2022; 67:1506-1515. [DOI: 10.1016/j.survophthal.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 02/11/2022] [Accepted: 02/14/2022] [Indexed: 10/19/2022]
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Candy TR, Cormack LK. Recent understanding of binocular vision in the natural environment with clinical implications. Prog Retin Eye Res 2021; 88:101014. [PMID: 34624515 PMCID: PMC8983798 DOI: 10.1016/j.preteyeres.2021.101014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/26/2021] [Accepted: 09/29/2021] [Indexed: 10/20/2022]
Abstract
Technological advances in recent decades have allowed us to measure both the information available to the visual system in the natural environment and the rich array of behaviors that the visual system supports. This review highlights the tasks undertaken by the binocular visual system in particular and how, for much of human activity, these tasks differ from those considered when an observer fixates a static target on the midline. The everyday motor and perceptual challenges involved in generating a stable, useful binocular percept of the environment are discussed, together with how these challenges are but minimally addressed by much of current clinical interpretation of binocular function. The implications for new technology, such as virtual reality, are also highlighted in terms of clinical and basic research application.
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Affiliation(s)
- T Rowan Candy
- School of Optometry, Programs in Vision Science, Neuroscience and Cognitive Science, Indiana University, 800 East Atwater Avenue, Bloomington, IN, 47405, USA.
| | - Lawrence K Cormack
- Department of Psychology, Institute for Neuroscience, and Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, 78712, USA.
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Pladere T, Luguzis A, Zabels R, Smukulis R, Barkovska V, Krauze L, Konosonoka V, Svede A, Krumina G. When virtual and real worlds coexist: Visualization and visual system affect spatial performance in augmented reality. J Vis 2021; 21:17. [PMID: 34388233 PMCID: PMC8363769 DOI: 10.1167/jov.21.8.17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/16/2021] [Indexed: 11/24/2022] Open
Abstract
New visualization approaches are being actively developed aiming to mitigate the effect of vergence-accommodation conflict in stereoscopic augmented reality; however, high interindividual variability in spatial performance makes it difficult to predict user gain. To address this issue, we investigated the effects of consistent and inconsistent binocular and focus cues on perceptual matching in the stereoscopic environment of augmented reality using a head-mounted display that was driven in multifocal and single focal plane modes. Participants matched the distance of a real object with images projected at three viewing distances, concordant with the display focal planes when driven in the multifocal mode. As a result, consistency of depth cues facilitated faster perceptual judgments on spatial relations. Moreover, the individuals with mild binocular and accommodative disorders benefited from the visualization of information on the focal planes corresponding to image planes more than individuals with normal vision, which was reflected in performance accuracy. Because symptoms and complaints may be absent when the functionality of the sensorimotor system is reduced, the results indicate the need for a detailed assessment of visual functions in research on spatial performance. This study highlights that the development of a visualization system that reduces visual stress and improves user performance should be a priority for the successful implementation of augmented reality displays.
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Affiliation(s)
- Tatjana Pladere
- Department of Optometry and Vision Science, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
| | - Artis Luguzis
- Department of Optometry and Vision Science, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
- Laboratory of Statistical Research and Data Analysis, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
| | | | | | - Viktorija Barkovska
- Department of Optometry and Vision Science, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
| | - Linda Krauze
- Department of Optometry and Vision Science, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
| | - Vita Konosonoka
- Department of Optometry and Vision Science, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
| | - Aiga Svede
- Department of Optometry and Vision Science, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
| | - Gunta Krumina
- Department of Optometry and Vision Science, Faculty of Physics, Mathematics and Optometry, University of Latvia, Riga, Latvia
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Fogt N. Comparisons of proximal vergence measures. VISION DEVELOPMENT AND REHABILITATION 2020; 6:252-263. [PMID: 33283044 PMCID: PMC7717499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
BACKGROUND Proximal vergence is defined as a vergence eye movement subtype driven by an "awareness of nearness". The purpose of this experiment was to compare values of proximal vergence calculated with and without measures of accommodation to assess the clinical utility of each measurement method. METHODS Thirteen participants between the ages of 22 and 37 (mean = 28.5 ± 4.5 years) were enrolled. The distance and near heterophoria were measured using the Modified Thorington technique. The near heterophoria was measured under three randomized viewing conditions (no lenses, +1.00D lenses, +2.50D lenses). Refractive error was measured with an autorefractor. Proximal vergence was calculated as the difference in calculated (far-near) and gradient (+1.00) stimulus AC/A ratios (stimulus AC/A differencing method), the difference in calculated and gradient response AC/A ratios (response AC/A differencing method), and the change in vergence from distance to near with the +2.50D lenses (uncorrected +2.50D method). This latter value was also corrected for any active accommodation with +2.50D lenses (corrected +2.50D method). RESULTS The mean proximal vergence values (Δ) were 7.82 ± 5.98 (stimulus AC/A differencing method), 8.29 ± 3.30 (response AC/A differencing method), 6.23 ± 3.52 (uncorrected +2.50D method), and 5.13 ± 2.98 (corrected +2.50D method). The only comparison that showed both a significant correlation (p<0.05) and a non-significant difference from the paired t-test (p>0.05) was that between the stimulus AC/A differencing method and the uncorrected +2.50D method. CONCLUSIONS When response accommodation was accounted for, differences occurred in the mean proximal values obtained with the various methods. The means of the methods most likely to be used clinically (stimulus AC/A differencing method and uncorrected +2.50D method) were similar, although some individuals demonstrated significant differences between these methods.
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Affiliation(s)
- Nick Fogt
- The Ohio State University College of Optometry
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Candy TR. The Importance of the Interaction Between Ocular Motor Function and Vision During Human Infancy. Annu Rev Vis Sci 2019; 5:201-221. [PMID: 31525140 DOI: 10.1146/annurev-vision-091718-014741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Numerous studies have demonstrated the impact of imposed abnormal visual experience on the postnatal development of the visual system. These studies have provided fundamental insights into the mechanisms underlying neuroplasticity and its role in clinical care. However, the ocular motor responses of postnatal human infants largely define their visual experience in dynamic three-dimensional environments. Thus, the immature visual system needs to control its own visual experience. This review explores the interaction between the developing motor and sensory/perceptual visual systems, together with its importance in both typical development and the development of forms of strabismus and amblyopia.
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Affiliation(s)
- T Rowan Candy
- Optometry & Vision Science, School of Optometry; Psychological & Brain Sciences; and Neuroscience and Cognitive Science, Indiana University, Bloomington, Indiana 47401, USA;
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Ghahghaei S, Reed O, Candy TR, Chandna A. Calibration of the PlusOptix PowerRef 3 with change in viewing distance, adult age and refractive error. Ophthalmic Physiol Opt 2019; 39:253-259. [PMID: 31236979 PMCID: PMC6852400 DOI: 10.1111/opo.12631] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/28/2019] [Indexed: 11/30/2022]
Abstract
Purpose The PowerRef 3 is frequently used in studying the near triad of accommodation, vergence and pupil responses in normal and clinical populations. Within a range, the defocus measurement of the PowerRef 3 is linearly related to the eye's defocus. While the default factory‐calibrated slope of this relation (calibration factor) is 1, it has been shown that the slope can vary across individuals. Here, we addressed the impact of changes in viewing distance, age and defocus of the eye on the calibration factor. Methods We manipulated viewing distance (40 cm, 1 m and 6 m) and recruited participants with a range of accommodative capabilities: participants in their 20s, 40s and over 60 years old. To test whether any effect was larger than the range of measurement reliability of the instrument, we collected data for each condition four times: two in the same session, another on the same day, and one on a different day. Results The results demonstrated that viewing distance did not affect the calibration factor over the linear range, regardless of age or uncorrected refractive error. The largest proportion of the variance was explained by between‐subject differences. Conclusions Calibration data for the PowerRef 3 were not sensitive to changes in viewing distance. Nevertheless, our results re‐emphasise the relevance of calibration for studies of individual participants.
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Affiliation(s)
| | - Olivia Reed
- Indiana University School of Optometry, Bloomington, USA
| | - T Rowan Candy
- Indiana University School of Optometry, Bloomington, USA
| | - Arvind Chandna
- The Smith-Kettlewell Eye Research Institute, San Francisco, USA
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Schiavi C, Di Croce V, Primavera L, Tassi F. Convergence, Accommodation, Fusion, and Stereopsis: What Keeps the Eyes Aligned in Intermittent Exotropia? SCIENTIFICA 2018; 2018:9546979. [PMID: 30147984 PMCID: PMC6083647 DOI: 10.1155/2018/9546979] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/12/2018] [Indexed: 06/08/2023]
Abstract
PURPOSE To investigate the relationships between angle of deviation, fusional convergence and divergence amplitude, AC/A ratio, near point of convergence (NPC), and myopia-phoria in intermittent exotropia (IXT). METHODS 93 patients with IXT, divided into two groups, were recruited in the study. In Group A (73 patients), fusional convergence and divergence amplitudes, NPC, and AC/A ratio were studied and compared with a control group. In Group B (in 20 patients), myopia-phoria while switching from monocular to binocular view was studied with an infrared video retinoscopy and compared with a control group. RESULTS In Group A, positive fusional amplitudes, NPC, and AC/A ratio of IXT patients did not differ from those of normals. Negative fusional amplitudes were significantly higher in the patient group than in the control group. In Group B, myopic shift was statistically significantly higher in the patient group and there was a statistically significant positive correlation between myopic shift and angle of strabismus. CONCLUSIONS Apart from the role of fusional convergence which accounts for myopia-phoria, that of the other binocular functions in the control at near of IXT and conversely their specific role in the pathogenesis of IXT remain unclear and the cause of divergent infantile strabismus is still unknown.
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Affiliation(s)
- Costantino Schiavi
- Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Ophthalmology Service, St. Orsola-Malpighi Teaching Hospital, University of Bologna, Via P. Palagi 9, 40138 Bologna, Italy
| | - Valentina Di Croce
- Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Ophthalmology Service, St. Orsola-Malpighi Teaching Hospital, University of Bologna, Via P. Palagi 9, 40138 Bologna, Italy
| | - Laura Primavera
- Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Ophthalmology Service, St. Orsola-Malpighi Teaching Hospital, University of Bologna, Via P. Palagi 9, 40138 Bologna, Italy
| | - Filippo Tassi
- Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Ophthalmology Service, St. Orsola-Malpighi Teaching Hospital, University of Bologna, Via P. Palagi 9, 40138 Bologna, Italy
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Horwood AM. 2016 International Orthoptic Congress Burian Lecture: Folklore or Evidence? Strabismus 2017; 25:120-127. [PMID: 28426269 PMCID: PMC5571894 DOI: 10.1080/09273972.2017.1305425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The theme of the 2016 Burian Lecture is how our understanding of strabismus has been changed by the research carried out in our laboratory in Reading over the years. Accommodation and convergence are fundamental to orthoptics, but actual responses have often been very different compared to what we had expected. This paper outlines how our laboratory's understanding of common issues such as normal development of accommodation and convergence, their linkage, intermittent strabismus, anisometropia, orthoptic exercises, and risk factors for strabismus have changed. A new model of thinking about convergence and accommodation may help us to better understand and predict responses in our patients.
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Affiliation(s)
- Anna M Horwood
- a Infant Vision Laboratory, School of Psychology & Clinical Language Sciences, University of Reading , Reading , United Kingdom
- b Orthoptic Department , Royal Berkshire Hospital , Reading , United Kingdom
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Determining the relative contribution of retinal disparity and blur cues to ocular accommodation in Down syndrome. Sci Rep 2017; 7:39860. [PMID: 28071728 PMCID: PMC5223174 DOI: 10.1038/srep39860] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 11/29/2016] [Indexed: 11/08/2022] Open
Abstract
Individuals with Down syndrome (DS) often exhibit hypoaccommodation alongside accurate vergence. This study investigates the sensitivity of the two systems to retinal disparity and blur cues, establishing the relationship between the two in terms of accommodative-convergence to accommodation (AC/A) and convergence-accommodation to convergence (CA/C) ratios. An objective photorefraction system measured accommodation and vergence under binocular conditions and when retinal disparity and blur cues were removed. Participants were aged 6–16 years (DS n = 41, controls n = 76). Measures were obtained from 65.9% of participants with DS and 100% of controls. Accommodative and vergence responses were reduced with the removal of one or both cues in controls (p < 0.007). For participants with DS, removal of blur was less detrimental to accommodative responses than removal of disparity; accommodative responses being significantly better when all cues were available or when blur was removed in comparison to when proximity was the only available cue. AC/A ratios were larger and CA/C ratios smaller in participants with DS (p < 0.00001). This study demonstrates that retinal disparity is the main driver to both systems in DS and illustrates the diminished influence of retinal blur. High AC/A and low CA/C ratios in combination with disparity-driven responses suggest prioritisation of vergence over accurate accommodation.
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Abstract
PURPOSE To compare the accommodative gain and pupil miosis of children with only one functional eye with the binocular and monocular accommodative and pupil responses of typically developing age-matched controls. METHODS Forty-one uniocular cases and 43 controls (3-14 years for both cohorts) watched a cartoon movie on an LCD screen that ramped between 90 and 30 cm, with a stable period of 4 seconds at both viewing distances. Cases performed the task with their only functional eye whereas controls performed the task binocularly and monocularly. A subset of subjects also repeated the task while reading 20/40-sized letters on the LCD screen. Accommodative and pupil responses were recorded using the Plusoptix PowerRef3 photorefractor. RESULTS Accommodative gain of cases [median (25th-75th IQR): 0.73 (0.60-0.85)] was larger than the monocular gain of controls [0.56 (0.47-0.79)] (P = .03). Both responses were lower than the binocular gain of controls [0.95 (0.81-1.11)] (P < .001). Uniocular pupil miosis of cases [0.14 mm (0.06-0.24 mm)] were similar to monocular [0.12 mm (0.05-0.29 mm)] (P = .69) and smaller than binocular [0.23 mm (0.14-0.34 mm)] (P < .001) responses of controls. The increase in accommodative gain from movie watching to reading was significant only for controls (P = .02) but not for cases (P = .15). Age and time of visual deficit were poorly correlated with accommodative gain and pupil miosis of cases (r ≤ 0.25; P ≥ .1 for all). Age was also poorly correlated with the binocular and monocular accommodative and pupil performance of controls (r ≤ -0.3; P = .33). CONCLUSIONS The accommodative gain of children with permanent loss of binocularity is in between the binocular and monocular gains of typically developing children. Their accommodative gains do not show any significant increase with a cognitively demanding task even while such a behavior is observed in controls. Pupil responses of uniocular children are similar to the monocular responses of age-matched controls.
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