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Ghasia F, Tychsen L. Inter-Ocular Fixation Instability of Amblyopia: Relationship to Visual Acuity, Strabismus, Nystagmus, Stereopsis, Vergence, and Age. Am J Ophthalmol 2024; 267:230-248. [PMID: 38944136 DOI: 10.1016/j.ajo.2024.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/21/2024] [Accepted: 06/14/2024] [Indexed: 07/01/2024]
Abstract
PURPOSE Amblyopia damages visual sensory and ocular motor functions. One manifestation of the damage is abnormal fixational eye movements. Tiny fixation movements are normal; however, when these exceed a normal range, the behavior is labeled "fixation instability" (FI). Here we compare FI between normal and amblyopic subjects, and evaluate the relationship between FI and severity of amblyopia, strabismus angle, nystagmus, stereopsis, vergence, and subject age. METHODS Fixation eye movements were recorded using infrared video-oculography from 47 controls (15.3 ± 12.2 years of age) and 104 amblyopic subjects (13.3 ± 11.2 years of age) during binocular and monocular viewing. FI and vergence instability were quantified as the bivariate contour ellipse area (BCEA). We also calculated the ratio of FI between the 2 eyes: right eye/left eye for controls, amblyopic eye/fellow eye for amblyopes. Multiple regression analysis evaluated how FI related to a range of visuo-motor measures. RESULTS During binocular viewing, the FI of fellow and amblyopic eye, vergence instability, and inter-ocular FI ratios were least in anisometropic and most in mixed amblyopia (P < .05). Each correlated positively with the strabismus angle (P < .01). During monocular viewing, subjects with deeper amblyopia (P < .01) and larger strabismus angles (P < .05) had higher inter-ocular FI ratios. In all, 27% of anisometropic and >65% of strabismic/mixed amblyopes had nystagmus. Younger age and nystagmus increased FI and vergence instability (P < .05) but did not affect the inter-ocular FI ratios (P > .05). CONCLUSIONS Quantitative recording of perturbed eye movements in children reveal a major functional deficit linked to amblyopia. Imprecise fixation, measured as inter-ocular FI ratios, may be used as a robust marker for amblyopia and strabismus severity. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
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Affiliation(s)
- Fatema Ghasia
- From the Neurosciences and Ocular Motility Laboratory (F.G.), Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA.
| | - Lawrence Tychsen
- Department of Ophthalmology and Visual Sciences (L.T.), St Louis Children's Hospital at Washington University School of Medicine, St. Louis, Missouri, USA
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Cakir GB, Murray J, Dulaney C, Ghasia F. Multifaceted Interactions of Stereoacuity, Inter-Ocular Suppression, and Fixation Eye Movement Abnormalities in Amblyopia and Strabismus. Invest Ophthalmol Vis Sci 2024; 65:19. [PMID: 38470326 PMCID: PMC10941996 DOI: 10.1167/iovs.65.3.19] [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: 10/23/2023] [Accepted: 02/19/2024] [Indexed: 03/13/2024] Open
Abstract
Purpose Amblyopic and strabismus subjects experience inter-ocular suppression, impaired stereoacuity, and increased fixation instability. The purpose of the study was to investigate factors affecting suppression and stereoacuity and examine their relationship to fixation eye movement (FEM) abnormalities. Methods We recruited 14 controls and 46 amblyopic subjects (anisometropic = 18, strabismic = 14, and mixed = 14) and 11 subjects with strabismus without amblyopia. We utilized the dichoptic motion coherence test to quantify suppression, and stereoacuity was assessed using the Titmus Fly test. We recorded FEMs using high-resolution video-oculography and classified subjects that did not have nystagmus (n = 27) versus those with nystagmus (n = 32; fusion maldevelopment nystagmus [FMN], n = 10) and nystagmus that did not meet the criteria of FMN (n = 20). We also recorded FEMs under dichoptic viewing (DcV) at varied fellow eye (FE) contrasts and computed the amplitude and velocity of the fast and slow FEMs and vergence instability. Results Inter-ocular suppression and stereoacuity deficits were closely correlated with an amblyopic eye (AE), visual acuity, and strabismus angle. Subjects with nystagmus displayed more pronounced stereoacuity deficits than those without nystagmus. Strabismic subjects with and without amblyopia, who demonstrated a fixation switch at 100% FE contrast, had lower inter-ocular suppression than subjects lacking a fixation switch under DcV. Amplitude of fast FEMs and velocity of slow FEMs, and vergence instability were increased as the FE contrast was lowered in both amblyopic and strabismic subjects. Conclusions The current study highlights the intricate relationships between AE visual acuity, eye deviation, and FEM abnormalities on suppression and stereoacuity deficits and underscores the need to evaluate FEM abnormalities while assessing dichoptic treatment outcomes.
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Affiliation(s)
- Gokce Busra Cakir
- Ocular Motility & Vision Neurosciences Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Jordan Murray
- Ocular Motility & Vision Neurosciences Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Cody Dulaney
- Ocular Motility & Vision Neurosciences Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Fatema Ghasia
- Ocular Motility & Vision Neurosciences Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
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Nieboer W, Ghiani A, de Vries R, Brenner E, Mann DL. Eye Tracking to Assess the Functional Consequences of Vision Impairment: A Systematic Review. Optom Vis Sci 2023; 100:861-875. [PMID: 38165789 DOI: 10.1097/opx.0000000000002088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024] Open
Abstract
BACKGROUND Eye tracking is a promising method for objectively assessing functional visual capabilities, but its suitability remains unclear when assessing the vision of people with vision impairment. In particular, accurate eye tracking typically relies on a stable and reliable image of the pupil and cornea, which may be compromised by abnormalities associated with vision impairment (e.g., nystagmus, aniridia). OBJECTIVES This study aimed to establish the degree to which video-based eye tracking can be used to assess visual function in the presence of vision impairment. DATA SOURCES A systematic review was conducted using PubMed, EMBASE, and Web of Science databases, encompassing literature from inception to July 2022. STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS Studies included in the review used video-based eye tracking, included individuals with vision impairment, and used screen-based tasks unrelated to practiced skills such as reading or driving. STUDY APPRAISAL AND SYNTHESIS METHODS The included studies were assessed for quality using the Strengthening the Reporting of Observational Studies in Epidemiology assessment tool. Data extraction and synthesis were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS Our analysis revealed that five common tests of visual function were used: (i) fixation stability, (ii) smooth pursuit, (iii) saccades, (iv) free viewing, and (v) visual search. The studies reported considerable success when testing individuals with vision impairment, yielding usable data from 96.5% of participants. LIMITATIONS There was an overrepresentation of conditions affecting the optic nerve or macula and an underrepresentation of conditions affecting the anterior segment or peripheral retina. CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS The results offer promise for the use of eye tracking to assess the visual function of a considerable proportion of those with vision impairment. Based on the findings, we outline a framework for how eye tracking can be used to test visual function in the presence of vision impairment.
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Affiliation(s)
| | - Andrea Ghiani
- Department of Human Movement Sciences, Amsterdam Movement Sciences and Institute of Brain and Behaviour Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Ralph de Vries
- Medical Library, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Eli Brenner
- Department of Human Movement Sciences, Amsterdam Movement Sciences and Institute of Brain and Behaviour Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - David L Mann
- Department of Human Movement Sciences, Amsterdam Movement Sciences and Institute of Brain and Behaviour Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
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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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Chen Y, You W, Hu Y, Chu H, Chen X, Shi W, Gao X. EEG measurement for the effect of perceptual eye position and eye position training on comitant strabismus. Cereb Cortex 2023; 33:10194-10206. [PMID: 37522301 PMCID: PMC10502583 DOI: 10.1093/cercor/bhad275] [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: 05/16/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 08/01/2023] Open
Abstract
One of the clinical features of comitant strabismus is that the deviation angles in the first and second eye positions are equal. However, there has been no report of consistency in the electroencephalography (EEG) signals between the 2 positions. In order to address this issue, we developed a new paradigm based on perceptual eye position. We collected steady-state visual evoked potentials (SSVEPs) signals and resting-state EEG data before and after the eye position training. We found that SSVEP signals could characterize the suppression effect and eye position effect of comitant strabismus, that is, the SSVEP response of the dominant eye was stronger than that of the strabismus eye in the first eye position but not in the second eye position. Perceptual eye position training could modulate the frequency band activities in the occipital and surrounding areas. The changes in the visual function of comitant strabismus after training could also be characterized by SSVEP. There was a correlation between intermodulation frequency, power of parietal electrodes, and perceptual eye position, indicating that EEG might be a potential indicator for evaluating strabismus visual function.
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Affiliation(s)
- Yuzhen Chen
- Shenzhen International Graduate School, Tsinghua University, Nanshan District, Shenzhen 518055, China
| | - Weicong You
- Shenzhen International Graduate School, Tsinghua University, Nanshan District, Shenzhen 518055, China
| | - Yijun Hu
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Haidian District, Beijing 100084, China
| | - Hang Chu
- The National Engineering Research Center for Healthcare Devices, Tianhe District, Guangzhou 510500, China
| | - Xiaogang Chen
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Nankai District, Tianjin 300192, China
| | - Wei Shi
- Department of Ophthalmology, Beijing Children’s Hospital, Capital Medical University, Xicheng District, Beijing 100045, China
| | - Xiaorong Gao
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Haidian District, Beijing 100084, China
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Huang Y, Liu Z, Wang M, Gao L, Wu Y, Hu J, Zhang Z, Yan FF, Deng D, Huang CB, Yu M. Cortical Reorganization After Optical Alignment in Strabismic Patients Outside of Critical Period. Invest Ophthalmol Vis Sci 2023; 64:5. [PMID: 37535007 PMCID: PMC10408769 DOI: 10.1167/iovs.64.11.5] [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: 03/22/2023] [Accepted: 07/17/2023] [Indexed: 08/04/2023] Open
Abstract
PURPOSE To measure visual crowding, an essential bottleneck on object recognition and reliable psychophysical index of cortex organization, in older children and adults with horizontal concomitant strabismus before and after strabismus surgery. METHODS Using real-time eye tracking to ensure gaze-contingent display, we examined the peripheral visual crowding effects in older children and adults with horizontal concomitant strabismus but without amblyopia before and after strabismus surgery. Patients were asked to discriminate the orientation of the central tumbling E target letter with flankers arranged along the radial or tangential axis in the nasal or temporal hemifield at different eccentricities (5° or 10°). The critical spacing value, which is the minimum space between the target and the flankers required for correct discrimination, was obtained for comparisons before and after strabismus surgery. RESULTS Twelve individuals with exotropia (6 males, 21.75 ± 7.29 years, mean ± SD) and 15 individuals with esotropia (6 males, 24.13 ± 5.96 years) participated in this study. We found that strabismic individuals showed significantly larger critical spacing with nasotemporal asymmetry along the radial axis that related to the strabismus pattern, with exotropes exhibiting stronger temporal field crowding and esotropes exhibiting stronger nasal field crowding before surgical alignment. After surgery, the critical spacing was reduced and rebalanced between the nasal and temporal hemifields. Furthermore, the postoperative recovery of stereopsis was associated with the extent of nasotemporal balance of critical spacing. CONCLUSIONS We find that optical realignment (i.e., strabismus surgery) can normalize the enlarged visual crowding effects, a reliable psychophysical index of cortical organization, in the peripheral visual field of older children and adults with strabismus and rebalance the nasotemporal asymmetry of crowding, promoting the recovery of postoperative stereopsis. Our results indicated a potential of experience-dependent cortical organization after axial alignment even for individuals who are out of the critical period of visual development, illuminating the capacity and limitations of optics on sensory plasticity and emphasizing the importance of ocular correction for clinical practice.
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Affiliation(s)
- Yiru Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Zitian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Mingqin Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Le Gao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Yanyan Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Jingyi Hu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Zhenyu Zhang
- Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences (CAS), Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Fang-Fang Yan
- Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences (CAS), Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Daming Deng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Chang-Bing Huang
- Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences (CAS), Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Minbin Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
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Huang Y, Liu Z, Chen Z, Zhan Z, Gao L, Hu J, Wu Y, Yan FF, Deng D, Huang CB, Yu M. Visual Crowding Reveals Field- and Axis-Specific Cortical Miswiring After Long-Term Axial Misalignment in Strabismic Patients Without Amblyopia. Invest Ophthalmol Vis Sci 2023; 64:10. [PMID: 36652265 PMCID: PMC9855284 DOI: 10.1167/iovs.64.1.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Purpose Inspired by physiological and neuroimaging findings that revealed squint-induced modification of cortical volume and visual receptive field in early visual areas, we hypothesized that strabismic eyes without amblyopia manifest an increase in critical spacing of visual crowding, an essential bottleneck on object recognition and reliable psychophysical index of cortical organization. Methods We used real-time eye tracking to ensure gaze-contingent display and examined visual crowding in patients with horizontal concomitant strabismus (both esotropia and exotropia) but without amblyopia and age-matched normal controls. Results Nineteen patients with exotropia (12 men, mean ± SD = 22.89 ± 7.82 years), 21 patients with esotropia (10 men, mean ± SD = 23.48 ± 6.95 years), and 14 age-matched normal controls (7 men, mean ± SD = 23.07 ± 1.07 years) participated in this study. We found that patients with strabismus without amblyopia showed significantly larger critical spacing with nasotemporal asymmetry in only the radial axis that related to the strabismus pattern, with exotropia exhibiting stronger temporal hemifield crowding and esotropia exhibiting stronger nasal hemifield crowding, in both the deviated and fixating eyes. Moreover, the magnitude of crowding change was related to the duration and degree of strabismic deviation. Conclusions Using visual crowding as a psychophysical index of cortical organization, our study demonstrated significantly greater peripheral visual crowding with nasotemporal asymmetry in only the radial axis in patients with strabismus without amblyopia, indicating the existence of hemifield- and axis-specific miswiring of cortical processing in object recognition induced by long-term adaptation to ocular misalignment.
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Affiliation(s)
- Yiru Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Zitian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Zidong Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Zongyi Zhan
- Shenzhen Eye Hospital, Shenzhen Eye Institute, Shenzhen Eye Hospital affiliated to Jinan University, Shenzhen, China,School of Optometry, Shenzhen University, Shenzhen, China
| | - Le Gao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Jingyi Hu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Yanyan Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Fang-Fang Yan
- Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences (CAS), Beijing, China,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Daming Deng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
| | - Chang-Bing Huang
- Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences (CAS), Beijing, China,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Minbin Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, Guangdong, China
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Reading difficulties in amblyopia: Consequence of visual sensory and oculomotor dysfunction. J Neurol Sci 2022; 442:120438. [PMID: 36242809 DOI: 10.1016/j.jns.2022.120438] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 09/17/2022] [Accepted: 09/22/2022] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Reading is a vision-reliant task, requiring sequential eye movements. Binocularly discordant input results in visual sensory and oculomotor dysfunction in amblyopia, which may contribute to reading difficulties. This study aims to determine the contributions of fixation eye movement (FEM) abnormalities, clinical type and severity of amblyopia to reading performance under binocular and monocular viewing conditions. METHODS Twenty-three amblyopic patients and nine healthy controls were recruited. Eye movements elicited during fixation and reading of preselected passages were collected for each subject using infrared video-oculography. Subjects were classified as having no nystagmus (n = 9), fusion maldevelopment nystagmus (FMN, n = 5), or nystagmus without structural anomalies that does not meet criteria for FMN or infantile nystagmus (n = 9). Reading rate (words/min), the number of forward and regressive saccades (per 100 words) and fixation duration (s) were computed. RESULTS Amblyopic patients with and without nystagmus exhibited greater vergence and fixation instability. In patients without nystagmus, the instability arises from increased amplitude and velocity of fast and slow FEMs respectively. Amblyopic patients with and without nystagmus exhibited lower reading speeds with increased fixation duration, regressive and progressive saccades than controls in all viewing conditions. Mixed etiology, greater amblyopic eye visual acuity and stereopsis deficits were associated with greater reading difficulties under binocular viewing. CONCLUSIONS The presence of oculomotor dysfunction and the extent of visual acuity and stereoacuity deficits contribute to reading difficulties in patients with amblyopia, with and without nystagmus. The understanding of reading difficulties is essential to devise accommodations to limit long-term academic and vocational consequences of amblyopia.
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Kelly KR, Norouzi DM, Nouredanesh M, Jost RM, Cheng-Patel CS, Beauchamp CL, Dao LM, Luu BA, Stager DR, Tung JY, Niechwiej-Szwedo E. Temporal Eye–Hand Coordination During Visually Guided Reaching in 7- to 12-Year-Old Children With Strabismus. Invest Ophthalmol Vis Sci 2022; 63:10. [DOI: 10.1167/iovs.63.12.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Krista R. Kelly
- Retina Foundation of the Southwest, Dallas, TX, United States
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, United States
| | | | - Mina Nouredanesh
- School of Rehabilitation Science, McMaster University, Hamilton, Ontario, Canada
| | - Reed M. Jost
- Retina Foundation of the Southwest, Dallas, TX, United States
| | | | | | - Lori M. Dao
- ABC Eyes Pediatric Ophthalmology, PA, Dallas, TX, United States
| | - Becky A. Luu
- Pediatric Ophthalmology & Adult Strabismus, PA, Plano, TX, United States
| | - David R. Stager
- Pediatric Ophthalmology & Adult Strabismus, PA, Plano, TX, United States
| | - James Y. Tung
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, Canada
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Zhou Y, Bian H, Yu X, Wen W, Zhao C. Quantitative assessment of eye movements using a binocular paradigm: comparison among amblyopic, recovered amblyopic and normal children. BMC Ophthalmol 2022; 22:365. [PMID: 36085016 PMCID: PMC9461109 DOI: 10.1186/s12886-022-02579-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 08/26/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To investigate the eye movement functions in children with amblyopia and recovered amblyopia by a binocular eye-tracking paradigm. METHODS Eye movements of 135 pediatric subjects (age range: 4-14 years), including 45 amblyopic children, 45 recovered amblyopic children and 45 age-similar normal controls, were recorded under binocular viewing with corrected refractive errors (if any). The deviation of gaze positions relative to the target location was recorded as the mean from both eyes. Main outcome measures included fixation deviations (degree) along horizontal and vertical axes in the sustained fixation test (Fix-X, Fix-Y) and visually guided saccade test (Sac-X, Sac-Y), which were compared across the three groups and between each two groups. RESULTS All the four deviations were significantly larger in the amblyopia group compared to the other two groups, indicating increased inaccuracy of sustained and post-saccadic fixations in amblyopia. However, there was no significant difference in deviations between recovered amblyopic children and normal controls. Repeated measures showed similar results overall and within each group. Mild to moderate amblyopes and severe amblyopes did not differ in the four deviations. No significant interaction was found between subject groups and clinical characteristics (age, refractive status, and anisometropia). CONCLUSION Amblyopic children have poor eye movement functions with increased inaccuracy of sustained and post-saccadic fixations, which appear to be restored in children with recovered amblyopia. Binocular assessment of eye movements provides valuable indicators of functional recovery in amblyopia.
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Affiliation(s)
- Yulian Zhou
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical School, Fudan University, Shanghai, 200031, China
- Key Laboratory of Myopia, Ministry of Health, Fudan University, Shanghai, 200031, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Hewei Bian
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical School, Fudan University, Shanghai, 200031, China
- Key Laboratory of Myopia, Ministry of Health, Fudan University, Shanghai, 200031, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Xiaobin Yu
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Wen Wen
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical School, Fudan University, Shanghai, 200031, China.
- Key Laboratory of Myopia, Ministry of Health, Fudan University, Shanghai, 200031, China.
- Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China.
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical School, Fudan University, 83 Fenyang Rd, Shanghai, 200031, China.
| | - Chen Zhao
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical School, Fudan University, Shanghai, 200031, China.
- Key Laboratory of Myopia, Ministry of Health, Fudan University, Shanghai, 200031, China.
- Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China.
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical School, Fudan University, 83 Fenyang Rd, Shanghai, 200031, China.
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11
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Ghasia F, Wang J. Amblyopia and fixation eye movements. J Neurol Sci 2022; 441:120373. [DOI: 10.1016/j.jns.2022.120373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 07/05/2022] [Accepted: 07/31/2022] [Indexed: 11/29/2022]
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12
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Chow A, Nallour Raveendran R, Erkelens I, Babu R, Thompson B. Increased saccadic latency in Amblyopia: Oculomotor and attentional factors. Vision Res 2022; 197:108059. [DOI: 10.1016/j.visres.2022.108059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 04/04/2022] [Accepted: 04/19/2022] [Indexed: 11/15/2022]
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13
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Hepokur M, Mutlu B, Güneş M, Topçu MT, Mutlu A, Oğuz H, Kalcıoğlu MT. The effect of different types of convergent strabismus on horizontal eye movements. Int Ophthalmol 2022; 42:3951-3961. [PMID: 35779198 DOI: 10.1007/s10792-022-02379-2] [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: 01/27/2022] [Accepted: 06/14/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE To investigate the effect of different types of convergent strabismus on horizontal eye movements and compare data with healthy control subjects. MATERIALS AND METHODS This prospective, cross-sectional study included 38 patients with convergent strabismus (16 fully accommodative, 13 partially accommodative and 9 non-accommodative esotropia) and 19 age-matched control subjects. All of the participants had a detailed ophthalmological examination including visual acuity assessment, cover-uncover prism test, slit lamp, and indirect ophthalmoscopy examination. Videonystagmography (VNG) was used for the evaluation of horizontal eye movements such as saccadic accuracy, velocity, latency, and smooth pursuit velocity gain. RESULTS The saccadic accuracy in the rightward direction was lower in the fully accommodative esotropia group compared to the partially accommodative esotropia group in the right eye (p = 0.002). The saccadic latency in the rightward direction was longer in the fully accommodative esotropia group compared to the control group (p = 0.008) and smooth pursuit velocity gain in the leftward direction was lower in the partially and non-accommodative esotropia group compared to the control group in binocular recording (p = 0.004, p = 0.001, respectively). There was no difference in the saccadic velocity among the study groups (p > 0.05). Finally, asymmetry of saccadic velocity and latency was observed between right- and leftward directions in the partially accommodative esotropia group in the right eye (p = 0.003, p = 0.008, respectively). CONCLUSION This study demonstrated that horizontal eye movements may vary in different types of convergent strabismus. VNG may be an auxiliary tool to the clinical examination in differentiating fully or non-accommodative esotropia.
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Affiliation(s)
- Mustafa Hepokur
- Cerrahpaşa Medical School, Department of Ophthalmology, Istanbul University-Cerrahpaşa, 34098, Istanbul, Turkey. .,Göztepe Süleyman Yalçın City Hospital, Ophthalmology Clinic, Istanbul, Turkey.
| | - Başak Mutlu
- Faculty of Health Sciences, Department of Audiology, Istanbul Medeniyet University, Istanbul, Turkey
| | - Medine Güneş
- Faculty of Medicine, Department of Ophthalmology, Istanbul Medeniyet University, Istanbul, Turkey.,Göztepe Süleyman Yalçın City Hospital, Ophthalmology Clinic, Istanbul, Turkey
| | - Merve Torun Topçu
- Faculty of Health Sciences, Department of Audiology, Istanbul Medeniyet University, Istanbul, Turkey
| | - Ahmet Mutlu
- Faculty of Medicine, Department of Otorhinolaryngology, Istanbul Medeniyet University, Istanbul, Turkey.,Göztepe Süleyman Yalçın City Hospital, Otorhinolaryngology Clinic, Istanbul, Turkey
| | - Halit Oğuz
- Faculty of Medicine, Department of Ophthalmology, Istanbul Medeniyet University, Istanbul, Turkey.,Göztepe Süleyman Yalçın City Hospital, Ophthalmology Clinic, Istanbul, Turkey
| | - Mahmut Tayyar Kalcıoğlu
- Faculty of Medicine, Department of Otorhinolaryngology, Istanbul Medeniyet University, Istanbul, Turkey.,Göztepe Süleyman Yalçın City Hospital, Otorhinolaryngology Clinic, Istanbul, Turkey
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14
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Kim SY, Moon BY, Cho HG, Yu DS. Comparison of image-based quantification methods in evaluating fixation stability using a remote eye tracker in abnormal phoria. J Int Med Res 2022; 50:3000605221098183. [PMID: 35546441 PMCID: PMC9112722 DOI: 10.1177/03000605221098183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 04/13/2022] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVE This study was performed to establish a quantitative evaluation and comparison of fixation stability, as measured by an eye tracker, using image-based areas determined by the bivariate contour ellipse area (BCEA), kernel density estimation (KDE), and Scanpath methods. METHODS This prospective cross-sectional study included 45 and 20 participants with abnormal and normal phoria, respectively. Eye movements were recorded using a remote eye tracker and were plotted using RStudio software. Image-based areas were evaluated using ImageJ software. RESULTS The image-based areas used to evaluate fixation stability exhibited decreasing stability in the abnormal phoria group in the following order: KDE with ±1 standard deviation (SD), BCEA with ±1 SD, KDE with ±2 SD or Scanpath, and BCEA with ±2 SD. The BCEA tended to be overestimated, and the KDE tended to be underestimated at high density. The Scanpath method had a very high probability area because the area spans all gaze points. CONCLUSIONS Fixation stability could be quantified as image-based areas by the KDE, BCEA, and Scanpath methods. Our findings suggest that fixation stability may be evaluated using one or more methods.
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Affiliation(s)
- Sang-Yeob Kim
- Department of Optometry, Kangwon National University, Samcheok, South Korea
| | - Byeong-Yeon Moon
- Department of Optometry, Kangwon National University, Samcheok, South Korea
| | - Hyun Gug Cho
- Department of Optometry, Kangwon National University, Samcheok, South Korea
| | - Dong-Sik Yu
- Department of Optometry, Kangwon National University, Samcheok, South Korea
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15
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Rohr JTD, Isaac CR, de Lima ADA, Garcia A, dos Santos PM, Tavares MCH. Study of Geometric Illusory Visual Perception – A New Perspective in the Functional Evaluation of Children With Strabismus. Front Hum Neurosci 2022; 16:769412. [PMID: 35496072 PMCID: PMC9043129 DOI: 10.3389/fnhum.2022.769412] [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: 09/03/2021] [Accepted: 03/23/2022] [Indexed: 11/17/2022] Open
Abstract
Despite the various perceptual-motor deficits documented in strabismus, there is a paucity of studies evaluating visual illusions in patients with strabismus. The aim of this study was to examine how the illusionary perception occurs in children/adolescents (10–15 years old) with strabismus with referral for surgery to correct ocular deviations. A controlled cross-sectional study was carried out in which 45 participants with strabismus and 62 healthy volunteers aged 10–15 years were evaluated. The behavioral response to three geometric illusions [Vertical-Horizontal illusion, Müller-Lyer illusion (Bretano version) and Ponzo illusion] and respective neutral stimuli (non-illusory images) regarding the estimation of image size and response time were measured using the Method of Adjustment. To analyze the influence of secondary factors: type of ocular deviation (convergent, divergent or associated with vertical deviation); amount of eye deviation; presence of amblyopia and stereopsis, a one-way ANOVA was performed. Among the tested illusions, children with strabismus showed greater susceptibility (p = 0.006) and response time (p = 0.004) to Ponzo’s illusory images. Children with strabismus and preserved stereopsis, on the other hand, showed similar susceptibility and response time to control group patients to the Ponzo illusion (p < 0.005). Patients with amblyopia showed overcorrection in the estimate of non-illusory Ponzo images (p = 0.046). Children with horizontal ocular deviation (esotropia or exotropia) associated with vertical deviation (hypertropia, DVD and/or alphabetical anisotropy) showed higher susceptibility to vertical adjustment images for the Müller-Lyer illusion (Brentano version) (p = 0.017). Individuals with strabismus tended to overcorrect the length of the straight-line segment adjusted for non-illusory images when testing non-illusory images in the Müller-Lyer test (Brentano version) (p = 0.009), as well as for the neutral images in the Vertical-Horizontal test (p = 0.000). The findings indicated impairment in the perception of geometric illusions and neutral figures, especially for the Ponzo illusion test by children with strabismus. As the behavioral response to illusory images may indirectly reflect the visual and morphofunctional alterations present in these individuals, we suggest that the investigation of visual illusory perception can be used as a new research strategy in the field of investigating the visual function in strabismus.
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Affiliation(s)
- Juliana Tessari Dias Rohr
- Department of Ophthalmology, Hospital de Base do Distrito Federal, Brasília, Brazil
- Department of Physiological Sciences, Institute of Biological Sciences, University of Brasília – UnB, Brasília, Brazil
- *Correspondence: Juliana Tessari Dias Rohr, ,
| | | | | | - Ana Garcia
- Department of Physiological Sciences, Institute of Biological Sciences, University of Brasília – UnB, Brasília, Brazil
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16
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Kim SY, Moon BY, Cho HG, Yu DS. Quantitative Evaluation of the Association Between Fixation Stability and Phoria During Short-Term Binocular Viewing. Front Neurosci 2022; 16:721665. [PMID: 35368249 PMCID: PMC8965591 DOI: 10.3389/fnins.2022.721665] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 02/11/2022] [Indexed: 11/29/2022] Open
Abstract
Purpose Fixation stability for binocular anomalies with a phoria cannot be detected by direct observations. This study aimed to quantitatively evaluate fixation stability using an eye tracker rather than direct directions in binocular vision with abnormal and normal phorias. Methods Thirty-five and 25 participants with abnormal and normal phoria, respectively, were included in the study. The horizontal and vertical gaze points and convergence were recorded for 10 s using a remote eye tracker while binocularly viewing a target on a display screen 550 mm away. Fixation stability was quantified using bivariate contour ellipse areas (BCEA). Results The fixation stability for all participants-based evaluations as a single cluster in the abnormal phoria group was lower than that in the normal phoria group (p = 0.005). There was no difference between the two groups in the evaluation based on the BCEA for each participant-based evaluation (p = 0.66). Fixation stability was also more related to convergence for the abnormal phoria group than for the normal phoria group (r = 0.769, p < 0.001; r = 0.417, p = 0.038, respectively). Conclusion As the first study to evaluate fixation stability using an eye-tracker to differentiate between abnormal and normal phoria for non-strabismus, these findings may provide evidence for improving the evaluation of binocular vision not detected with clinical diagnostic tests.
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17
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Murray J, Gupta P, Dulaney C, Garg K, Shaikh AG, Ghasia FF. Effect of Viewing Conditions on Fixation Eye Movements and Eye Alignment in Amblyopia. Invest Ophthalmol Vis Sci 2022; 63:33. [PMID: 35212720 PMCID: PMC8883146 DOI: 10.1167/iovs.63.2.33] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Patients with amblyopia are known to have fixation instability, which arises from alteration of physiologic fixation eye movements (FEMs) and nystagmus. We assessed the effects of monocular, binocular, and dichoptic viewing on FEMs and eye alignment in patients with and without fusion maldevelopment nystagmus (FMN). Methods Thirty-four patients with amblyopia and seven healthy controls were recruited for this study. Eye movements were recorded using infrared video-oculography during (1) fellow eye viewing (FEV), (2) amblyopic eye viewing (AEV), (3) both eye viewing (BEV), and (4) dichoptic viewing (DcV) at varying fellow eye (FE) contrasts. The patients were classified per the clinical type of amblyopia and FEM waveforms into those without nystagmus, those with nystagmus with and without FMN. Fixational saccades and intersaccadic drifts, quick and slow phases of nystagmus, and bivariate contour ellipse area were analyzed in the FE and amblyopic eye (AE). Results We found that FEMs are differentially affected with increased amplitude of quick phases of FMN observed during AEV than BEV and during DcV at lower FE contrasts. Increased fixation instability was seen in anisometropic patients at lower FE contrasts. Incomitance of eye misalignment was seen with the greatest increase during FEV. Strabismic/mixed amblyopia patients without FMN were more likely to demonstrate a fixation switch where the AE attends to the target during DcV than patients with FMN. Conclusions Our findings suggest that FEM abnormalities modulate with different viewing conditions as used in various amblyopia therapies. Increased FEM abnormalities could affect the visual function deficits and may have treatment implications.
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Affiliation(s)
- Jordan Murray
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Palak Gupta
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States.,Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States
| | - Cody Dulaney
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Kiran Garg
- Case Western Reserve University, Cleveland, Ohio, United States
| | - Aasef G Shaikh
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States.,Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States.,Department of Neurology, Neurological Institute, University Hospitals, Cleveland, Ohio, United States
| | - Fatema F Ghasia
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States.,Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States
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18
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Gupta P, Beylergil S, Murray J, Jacobs J, Kilbane C, Shaikh AG, Ghasia FF. Effects of Parkinson Disease on Blur-Driven and Disparity-Driven Vergence Eye Movements. J Neuroophthalmol 2021; 41:442-451. [PMID: 34788236 DOI: 10.1097/wno.0000000000001422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
ABSTRACT Synchronous movements of the 2 eyes in the opposite direction, disconjugate movements such as vergence, facilitate depth perception. The vergence eye movements are affected in Parkinson disease (PD). Visual blur (accommodation) and fusion (retinal disparity) are important triggers for the vergence. The neural circuit responsible for blur-driven and disparity-driven vergence is tightly coupled. We investigated the effect of PD on these 2 vergence paradigms. In the experiment involving 14 patients with PD and 6 healthy controls, substantial differences between blur-driven and disparity-driven vergence were found. The gain (ratio of actual vs desired eye movements) was reduced in patients with PD in case of disparity-driven vergence but not in blur-driven vergence. The latency of disparity-driven vergence onset was significantly longer for patients with PD compared with healthy controls. Four strategies were used to drive disparity-driven vergence: a) pure disconjugate vergence, b) conjugate saccadic movements, c) disconjugate vergence followed by saccadic movements, and d) conjugate saccades followed by disconjugate vergence movements. Blur-driven vergence had only 2 strategies: a) conjugate saccades followed by disconjugate vergence and b) conjugate saccadic movements only. The results are consistent with the prediction that PD primarily affects disparity-driven vergence, but there are some effects on the strategies to execute blur-driven vergence. We speculate that the deep cerebellar nuclei and the supraoculomotor area of the midbrain that carry the disparity-driven and blur-driven vergence are affected in PD. It is possible to modulate their function through projections to the subthalamic nuclei.
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Affiliation(s)
- Palak Gupta
- Department of Biomedical Engineering (PG, SB, AGS), Case Western Reserve University, Cleveland, Ohio; Daroff-Dell'Osso Ocular Motility Laboratory (PG, SB, JJ, AGS, FFG), Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio; Cole Eye Institute (JM, FFG), Cleveland Clinic, Cleveland, Ohio; and Department of Neurology (CK, AGS), Neurological Institute, University Hospitals, Cleveland, Ohio
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19
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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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20
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Gupta P, Beylergil S, Murray J, Kilbane C, Ghasia FF, Shaikh AG. Computational models to delineate 3D gaze-shift strategies in Parkinson's disease. J Neural Eng 2021; 18. [PMID: 34233315 DOI: 10.1088/1741-2552/ac123e] [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: 03/24/2021] [Accepted: 07/07/2021] [Indexed: 11/11/2022]
Abstract
Objective: Parkinson's disease (PD) frequently affects vergence eye movements interfering with the perception of depth and dimensionality critical for mitigating falls. We examined neural strategies that compensate for abnormal vergence and their mechanistic underpinning in PD.Approach:Thea priorihypothesis was that impaired vergence is compensated by incorporating rapid eye movements (saccades) to accomplish gaze shifts at different depths. Our experiments examined the hypothesis by simulating biologically plausible computational models of saccade-vergence interactions in PD and validating predictions in the actual patient data.Main results:We found four strategies to accomplish 3D gaze shift; pure vergence eye movements, pure saccadic eye movements, combinations of vergence followed by a saccade, and combination of saccade followed by vergence. The gaze shifting strategy of the two eyes was incongruent in PD. The latency of vergence was prolonged, and it was more so when the saccades preceded the vergence or when the saccades only made 3D gaze shift. Computational models predicted at least two possible mechanisms triggering saccades along with vergence. One is based on the lack of foveal accuracy when the vergence gain is suboptimal. The second mechanism reflects the noise in the gating mechanism, the omnipause neurons, for vergence and saccades. None of the two model predictions alone were completely supported by the patient data. However, a combined model incorporating both abnormal vergence velocity gain and impaired gating accurately simulated the results from PD patients.Significance:The combined strategy is biologically plausible for two reasons: (a) The basal ganglia that is prominently affected in PD projects to the vergence velocity neurons in the midbrain via the cerebellum. The projection directly affects the vergence velocity gain. (b) The basal ganglia, via superior colliculus, influences the pattern of omnipause neuronal activity. Abnormal basal ganglia activity may introduce noise in the omnipause neurons.
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Affiliation(s)
- Palak Gupta
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America.,Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States of America
| | - Sinem Beylergil
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America.,Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States of America
| | - Jordan Murray
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
| | - Camilla Kilbane
- Department of Neurology, University Hospitals, Cleveland, OH, United States of America
| | - Fatema F Ghasia
- Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States of America.,Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
| | - Aasef G Shaikh
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America.,Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States of America.,Department of Neurology, University Hospitals, Cleveland, OH, United States of America
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21
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Martin TL, Murray J, Garg K, Gallagher C, Shaikh AG, Ghasia FF. Fixation eye movement abnormalities and stereopsis recovery following strabismus repair. Sci Rep 2021; 11:14417. [PMID: 34257361 PMCID: PMC8277881 DOI: 10.1038/s41598-021-93919-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 06/30/2021] [Indexed: 02/06/2023] Open
Abstract
We evaluated the effects of strabismus repair on fixational eye movements (FEMs) and stereopsis recovery in patients with fusion maldevelopment nystagmus (FMN) and patients without nystagmus. Twenty-one patients with strabismus, twelve with FMN and nine without nystagmus, were tested before and after strabismus repair. Eye-movements were recorded during a gaze-holding task under monocular viewing conditions. Fast (fixational saccades and quick phases of nystagmus) and slow (inter-saccadic drifts and slow phases of nystagmus) FEMs and bivariate contour ellipse area (BCEA) were analyzed in the viewing and non-viewing eye. Strabismus repair improved the angle of strabismus in subjects with and without FMN, however patients without nystagmus were more likely to have improvement in stereoacuity. The fixational saccade amplitudes and intersaccadic drift velocities in both eyes decreased after strabismus repair in subjects without nystagmus. The slow phase velocities were higher in patients with FMN compared to inter-saccadic drifts in patients without nystagmus. There was no change in the BCEA after surgery in either group. In patients without nystagmus, the improvement of the binocular function (stereopsis), as well as decreased fixational saccade amplitude and intersaccadic drift velocity, could be due, at least partially, to central adaptive mechanisms rendered possible by surgical realignment of the eyes. The absence of improvement in patients with FMN post strabismus repair likely suggests the lack of such adaptive mechanisms in patients with early onset infantile strabismus. Assessment of fixation eye movement characteristics can be a useful tool to predict functional improvement post strabismus repair.
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Affiliation(s)
- Talora L Martin
- Department of Neurology, Case Western Reserve University, Cleveland, OH, USA
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Jordan Murray
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Kiran Garg
- Department of Neurology, Case Western Reserve University, Cleveland, OH, USA
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Charles Gallagher
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Aasef G Shaikh
- Department of Neurology, Case Western Reserve University, Cleveland, OH, USA
- Daroff-Del'Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, OH, USA
- Neurology Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA
| | - Fatema F Ghasia
- Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA.
- Daroff-Del'Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, OH, USA.
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Murray J, Garg K, Ghasia F. Monocular and Binocular Visual Function Deficits in Amblyopic Patients with and without Fusion Maldevelopment Nystagmus. Eye Brain 2021; 13:99-109. [PMID: 33953627 PMCID: PMC8089081 DOI: 10.2147/eb.s300454] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 04/08/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose The aim of the study is to examine the association between amblyopia type and the presence of nystagmus on binocular and monocular functions of the fellow (FE) and amblyopic eye (AE). Methods We recruited 19 controls and 44 amblyopes (anisometropes=13, strabismic=10, mixed=21). We measured visual, grating, and vernier acuities and high/low spatial frequency (SF) contrast sensitivities in each eye using a staircase method. Stereoacuity was measured with the Titmus fly test. We recorded fixation eye movements (FEM) using high-resolution video-oculography. Subjects were classified as having either no nystagmus (n=18), fusion maldevelopment nystagmus syndrome (FMNS) (n=12), or nystagmus without any structural anomalies that does not meet the criteria for FMNS or infantile nystagmus (n=14). Results Analysis of visual function by clinical amblyopia type showed that patients with strabismus/mixed amblyopia (F (2,54)=9.5, p<0.001) were more likely to have poor stereopsis while controlling for AE grating acuity deficit. The FE of patients with anisometropia had greater contrast sensitivity deficits at low (F (2,43)=4.4, p=0.018) and high SF (F (2,42)=10.1, p<0.001). Analysis of visual function by FEM characteristics (low SF: (F (3,43)=4.3, p=0.010) and high SF: (F (3,42)=7.1, p=0.001) showed that the FE of patients with FMNS had worse low and high SF contrast sensitivities, whereas those without FMNS had greater contrast sensitivity deficits only at high SF compared to controls. Patients with FMNS (F (3,54) = 12.9, p<0.001) were more likely to have poor stereopsis while controlling for AE grating acuity deficit compared to patients without FMNS. All amblyopic patients had worse high SF contrast sensitivity of the AE irrespective of type or FEM characteristics (Type = F (2,43)=8.8, p=0.001; FEM characteristics= F (3,43)=5.1, p=0.004). Conclusion The presence of FMNS in patients with strabismic/mixed amblyopia is associated with poor/absent stereopsis. FE deficits vary across amblyopia type. Like FEM abnormalities, visual function deficits are seen in the FE of patients with and without nystagmus.
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Affiliation(s)
- Jordan Murray
- Cleveland Clinic Cole Eye Institute, Ophthalmological Research, Cleveland, OH, USA
| | - Kiran Garg
- Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Fatema Ghasia
- Cleveland Clinic Cole Eye Institute, Department of Ophthalmology, Cleveland, OH, 44195-0001, USA
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Scaramuzzi M, Murray J, Otero-Millan J, Nucci P, Shaikh AG, Ghasia FF. Part time patching treatment outcomes in children with amblyopia with and without fusion maldevelopment nystagmus: An eye movement study. PLoS One 2020; 15:e0237346. [PMID: 32790721 PMCID: PMC7425965 DOI: 10.1371/journal.pone.0237346] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/23/2020] [Indexed: 11/19/2022] Open
Abstract
PURPOSE We investigated how the abnormalities of fixation eye movements (FEMs) of the amblyopic eye were linked with treatment outcomes following part-time patching therapy in children with amblyopia. METHODS We recruited 53 patients, with at least 12 months of patching, and measured FEMs at the end of treatment. Subjects were classified based on FEM waveforms (those without nystagmus = 21, those with nystagmus without fusion maldevelopment nystagmus (FMN) = 21, and those with FMN = 11) and based on clinical type of amblyopia (anisometropic = 18, strabismic = 6, and mixed = 29). The treatment outcomes such as duration of treatment of receiving part-time patching therapy, visual acuity and stereo-acuity deficits at the end of treatment were determined. Bivariate contour ellipse area (BCEA), fast (fixational saccade/quick phases), and slow (inter-saccadic drifts/slow phases) FEMs of the fellow and amblyopic eye were analyzed. RESULTS Anisometropic group had less residual amblyopia (0.23±0.19logMAR acuity) compared to strabismic/mixed (0.36±0.26) groups (p = 0.007). Treatment duration in patients without nystagmus was lower (12.6±9.5months) compared to nystagmus without FMN (25.6±23.2) and FMN (29.5±20.4) groups (p = 0.006). Patients without nystagmus had better stereopsis at the end of treatment (2.3±0.84logarcsecs) compared to nystagmus without FMN (2.6±0.84) group (p = 0.003). The majority of patients with FMN (8/11) had absent stereopsis. BCEA of the amblyopic eye was higher in patients with greater residual visual acuity deficits in patients without nystagmus. No such association was seen in Nystagmus no FMN and FMN groups. Increased amplitude of fast FEMs, increased eye position variance and eye velocity of slow FEMs were seen in patients who had received longer duration of part time patching therapy and in those with greater residual amblyopia, and poor stereopsis at the end of treatment. CONCLUSIONS Assessment of FEM waveforms and fast and slow FEM characteristics are important measures while describing fixation instability in amblyopia. Several FEM abnormalities were associated with stereo-acuity and visual acuity deficits and treatment duration in patients with amblyopia treated with part time patching therapy.
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Affiliation(s)
- Matteo Scaramuzzi
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Department of Neuroscience, Unit of Ophthalmology, Istituto Giannina Gaslini, Genoa, Italy
- DISCCO, University of Milan, Milan, Italy
| | - Jordan Murray
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
| | - Jorge Otero-Millan
- Department of Neurology, The Johns Hopkins University, Baltimore, MD, United States of America
| | | | - Aasef G. Shaikh
- Daroff—Dell’Osso Ocular Motility Laboratory, Cleveland, OH, United States of America
- Case Medical Center, Case Western Reserve University, Cleveland, OH, United States of America
| | - Fatema F. Ghasia
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Daroff—Dell’Osso Ocular Motility Laboratory, Cleveland, OH, United States of America
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Tang S, Skelly P, Otero-Millan J, Jacobs J, Murray J, Shaikh AG, Ghasia FF. Effects of visual blur on microsaccades during visual exploration. J Eye Mov Res 2019; 12. [PMID: 33828759 PMCID: PMC7962686 DOI: 10.16910/jemr.12.6.10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Microsaccades shift the image on the fovea and counteract visual fading. They also serve as an optimal
sampling strategy while viewing complex visual scenes. Microsaccade production relies on the amount of
retinal error or acuity demand of a visual task. The goal of this study was to assess the effects of blur induced by uncorrected refractive error on visual search. Eye movements were recorded in fourteen healthy
subjects with uncorrected and corrected refractive error while they performed a) visual fixation b) blankscene viewing c) visual search (spot the difference) tasks. Microsaccades, saccades, correctly identified
differences and reaction times were analyzed. The frequency of microsaccades and correctly identified
differences were lower in the uncorrected refractive error during visual search. No similar change in microsaccades was seen during blank-scene viewing and gaze holding tasks. These findings suggest that visual
blur, hence the precision of an image on the fovea, has an important role in calibrating the amplitude of
microsaccades during visual scanning.
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Affiliation(s)
- Sherry Tang
- Case Western Reserve University School of Medicine, USA
| | | | - Jorge Otero-Millan
- Vestibular and Ocular Motor Research Laboratory, Johns Hopkins University, USA
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25
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Kang SL, Beylergil SB, Otero-Millan J, Shaikh AG, Ghasia FF. Fixational Eye Movement Waveforms in Amblyopia: Characteristics of Fast and Slow Eye Movements. J Eye Mov Res 2019; 12. [PMID: 33828757 PMCID: PMC7962684 DOI: 10.16910/jemr.12.6.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fixational eye movements comprise of fast microsaccades alternating with slow intersaccadic drifts. These physiologic eye movements play an important role in visual perception. Amblyopic patients are known to have fixation instability, particularly of the amblyopic eye. We examined eye movement abnormalities that contribute to this instability. We
found that fixation stability is affected by the presence of fusion maldevelopment nystagmus (FMN). However, some amblyopes can have nystagmus without nasally directed slow
phases and reversal in direction of the quick phase on ocular occlusion, features seen in
FMN. In patients without nystagmus, we found increased amplitude of fixational saccades
and inter-saccadic drifts. We categorized amblyopia patients by type (anisometropic,
strabismic, or mixed) and eye movement waveform (no nystagmus, nystagmus without
FMN, and FMN). We found specific fast and slow eye movement abnormalities of the
fellow and amblyopic eye during fellow, amblyopic and both eyes viewing conditions
across eye movement waveforms and types of amblyopia. These eye movement abnormalities can serve as biomarkers that can predict the impact of amblyopia as measured by
visual acuity and stereopsis. Evaluation of fixational eye movements in amblyopia could
be important to diagnose these common eye diseases and predict treatment effectiveness.
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Affiliation(s)
- Sarah L Kang
- Case Western Reserve University School of Medicine, Cleveland, USA
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Birch EE, Kelly KR, Giaschi DE. Fellow Eye Deficits in Amblyopia. J Binocul Vis Ocul Motil 2019; 69:116-125. [PMID: 31161888 PMCID: PMC6673659 DOI: 10.1080/2576117x.2019.1624440] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/23/2019] [Accepted: 05/23/2019] [Indexed: 10/26/2022]
Abstract
Amblyopia is a neurodevelopmental disorder of the visual system, as a result of discordant visual experience during infancy or early childhood. Because amblyopia is typically defined as monocularly reduced visual acuity accompanied by one or more known amblyogenic factors, it is often assumed that the fellow eye is normal and sufficient for tasks like reading and eye-hand coordination. Recent scientific evidence of ocular motor, visual, and visuomotor deficits that are present with fellow eye monocular viewing and with binocular viewing calls this assumption into question. This clinical update reviews the research that has revealed fellow ocular motor and visual deficits and the effect that these deficits have on an amblyopic child's visuomotor and visuocognitive skills. We need to understand how to prevent and rehabilitate the effects of amblyopia not only on the nonpreferred eye but also on the fellow eye.
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Affiliation(s)
- Eileen E Birch
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, TX, USA
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, 11 USA
| | - Krista R Kelly
- Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, TX, USA
| | - Deborah E Giaschi
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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Scaramuzzi M, Murray J, Otero-Millan J, Nucci P, Shaikh AG, Ghasia FF. Fixation instability in amblyopia: Oculomotor disease biomarkers predictive of treatment effectiveness. PROGRESS IN BRAIN RESEARCH 2019; 249:235-248. [PMID: 31325983 DOI: 10.1016/bs.pbr.2019.04.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Amblyopic patients are known to have fixation instability, particularly of the amblyopic eye. The stability of the fixation is affected by the presence of nystagmus, the frequency and amplitude of fixational saccades and inter-saccadic drifts. Amblyopic patients without nystagmus have increased amplitude of the fixational saccades with reduced frequency of the physiologic microsaccades and have increased inter-saccadic drifts. Amblyopia patients who have experienced a disruption in binocularity in early infancy develop fusion maldevelopment nystagmus (FMN) previously called latent nystagmus as it is more evident during monocular viewing conditions. We have found that some amblyopic patients can have nystagmus with slow phases that are not directed nasally and without the reversal in direction on ocular occlusion, features seen in patients with FMN. The current mainstay of amblyopia treatment comprises of part-time occlusion therapy of the non-amblyopic eye. The amount of patching treatment is in the range of 2-6h/day as determined by the severity of amblyopia. Despite treatment, up to 40% of patients have residual amblyopia. We analyzed the effectiveness of part-time occlusion therapy in amblyopic patients as a function of fixation instability. We categorized amblyopic patients based on their eye movement waveforms obtained during a visual fixation task into those lacking nystagmus, those with FMN and those with nystagmus but no FMN. We did a retrospective chart review to gather information about their clinical characteristics and treatment response. We found that patients with FMN require a more prolonged duration of treatment and have a poorer recovery of stereopsis compared to patients with nystagmus but no FMN and patients lacking nystagmus. This study suggests that eye movement assessment provides valuable information in the management of amblyopia.
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Affiliation(s)
- Matteo Scaramuzzi
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States; San Giuseppe Eye Clinic, Milan, Italy; University of Milan, Milan, Italy
| | - Jordan Murray
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Jorge Otero-Millan
- Department of Neurology, The Johns Hopkins University, Baltimore, MD, United States
| | - Paolo Nucci
- San Giuseppe Eye Clinic, Milan, Italy; University of Milan, Milan, Italy
| | - Aasef G Shaikh
- Daroff-Dell'Osso Ocular Motility Laboratory, Cleveland, OH, United States; Case Medical Center, Case Western Reserve University, Cleveland, OH, United States
| | - Fatema F Ghasia
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States; Daroff-Dell'Osso Ocular Motility Laboratory, Cleveland, OH, United States.
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28
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Chen D, Otero-Millan J, Kumar P, Shaikh AG, Ghasia FF. Visual Search in Amblyopia: Abnormal Fixational Eye Movements and Suboptimal Sampling Strategies. Invest Ophthalmol Vis Sci 2019; 59:4506-4517. [PMID: 30208418 DOI: 10.1167/iovs.18-24794] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Microsaccades shift the image on the fovea and counteract visual fading. They are also thought to serve as an optimal sampling strategy while viewing complex visual scenes. The goal of our study was to assess visual search in amblyopic children. Methods Twenty-one amblyopic children with varying severity of amblyopia and 10 healthy controls were recruited. Eye movements were recorded using infrared video-oculography during amblyopic and fellow eye viewing while the subjects performed (1) visual fixation, (2) exploration of a blank scene, and (3) visual search task (spot the difference between two images). The number of correctly identified picture differences and reaction time were recorded. Microsaccade, saccades, and intersaccadic drifts were analyzed in patients without latent nystagmus (LN). Slow phase velocities were computed for patients with LN. Results Both patients with and without LN were able to spot the same number of differences but took longer during fellow eye viewing compared to controls. The ability to identify differences was diminished during amblyopic eye viewing particularly those with LN and severe amblyopia. We found reduced frequencies of microsaccades and saccades in both amblyopic and fellow eyes during fixation and visual search but not during exploration of blank scene. Across all tasks, amblyopes with LN had increased intersaccadic drifts. Conclusions Our findings suggest that deficient microsaccade and saccadic activity contributes to poorer sampling strategy in amblyopia, which is seen in both amblyopic and fellow eye. These deficits are more notable among subjects who experienced binocular decorrelation earlier in life, with subsequent development of LN.
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Affiliation(s)
- Dinah Chen
- Department of Ophthalmology, New York University School of Medicine, New York, New York, United States.,Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Jorge Otero-Millan
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland, United States
| | - Priyanka Kumar
- Department of Ophthalmology, the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
| | - Aasef G Shaikh
- Department of Neurology, University Hospitals, Case Western Reserve University, Cleveland, Ohio, United States.,Daroff-Dell'Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, Ohio, United States
| | - Fatema F Ghasia
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States.,Daroff-Dell'Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, Ohio, United States
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Ban JH, Moon SH. The Analysis of Ocular Deviations between Dominant and Non-dominant Eye Using Video-oculography in Intermittent Exotropia. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2019. [DOI: 10.3341/jkos.2019.60.7.685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Ji Hoon Ban
- Department of Ophthalmology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
- T2B Infrastructure Center for Ocular Disease, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
| | - Sung Hyuk Moon
- Department of Ophthalmology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
- T2B Infrastructure Center for Ocular Disease, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
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Fixation instability during binocular viewing in anisometropic and strabismic children. Exp Eye Res 2018; 183:29-37. [PMID: 30006273 DOI: 10.1016/j.exer.2018.07.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/16/2018] [Accepted: 07/09/2018] [Indexed: 11/22/2022]
Abstract
PURPOSE Strabismus or anisometropia disrupts binocularity and results in fixation instability, which is increased with amblyopia. Fixation instability has typically been assessed for each eye individually. Recently, vergence instability was reported in exotropic adults and monkeys during binocular viewing. We evaluated fixation instability during binocular viewing in children treated for anisometropia and/or strabismus. METHODS 160 children age 4-12 years with treated esotropia and/or anisometropia (98 amblyopic, 62 nonamblyopic) were compared to 46 age-similar controls. Fixation instability was recorded during binocular fixation of a 0.3 deg diameter dot for 20 s using a 500 Hz remote video binocular eye tracker (EyeLink 1000; SR Research). The bivariate contour ellipse area (BCEA; log deg2) for fixation instability was calculated for each eye (nonpreferred, preferred) and for vergence instability (left eye position - right eye position). Best-corrected visual acuity, Randot Preschool stereoacuity, and extent of suppression scotoma (Worth 4-Dot) were also obtained. RESULTS When binocularly viewing, both amblyopic and nonamblyopic children treated for anisometropia and/or strabismus had larger fixation instability and vergence instability than controls. Amblyopia primarily added to the instability of the nonpreferred eye. Anisometropic children had less nonpreferred eye instability and vergence instability than those with strabismus or combined mechanism. Nonpreferred eye instability and vergence instability were related to poorer stereoacuity and a larger suppression scotoma. Preferred eye instability was not related to any visual outcome measure. No relationships were found with visual acuity. CONCLUSIONS Fixation instability and vergence instability during binocular viewing suggests that discordant binocular visual experience during childhood, especially strabismus, interferes with ocular motor development. Amblyopia adds to instability of the nonpreferred eye. Vergence instability may limit potential for recovery of binocular vision in these children.
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Alexander RG, Macknik SL, Martinez-Conde S. Microsaccade Characteristics in Neurological and Ophthalmic Disease. Front Neurol 2018; 9:144. [PMID: 29593642 PMCID: PMC5859063 DOI: 10.3389/fneur.2018.00144] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 02/27/2018] [Indexed: 12/01/2022] Open
Abstract
Microsaccade research has recently reached a critical mass of studies that allows, for the first time, a comprehensive review of how microsaccadic dynamics change in neurological and ophthalmic disease. We discuss the various pathological conditions that affect microsaccades, their impact on microsaccadic and other fixational eye movement dynamics, and the incipient studies that point to microsaccadic features as potential indicators of differential and early diagnoses of multiple clinical conditions, from movement disorders to attention-deficit hyperactivity disorder to amblyopia. We propose that the objective assessment of fixational eye movement parameters may help refine differential diagnostics in neurological disease and assist in the evaluation of ongoing therapy regimes. In addition, determining the effects of ophthalmic disease on fixational eye movement features may help evaluate visual impairment in an objective manner, particularly in young patients or those experiencing communication difficulties.
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Affiliation(s)
- Robert G Alexander
- State University of New York (SUNY) Downstate Medical Center, Brooklyn, NY, United States
| | - Stephen L Macknik
- State University of New York (SUNY) Downstate Medical Center, Brooklyn, NY, United States
| | - Susana Martinez-Conde
- State University of New York (SUNY) Downstate Medical Center, Brooklyn, NY, United States
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