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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:S0002-9394(24)00263-0. [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; but 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. DESIGN AND METHODS Fixation Eye Movements were recorded using infra-red video-oculography from 47 controls(15.3±12.2y) and 104 amblyopic subjects(13.3±11.2y) during binocular and monocular viewing. FI and vergence instability were quantified as Bivariate Contour Ellipse Area (BCEA). We also calculated the ratio of FI between the two 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<0.05). Each correlated positively with the strabismus angle(p<0.01). During monocular viewing, subjects with deeper amblyopia(p<.01) and larger strabismus angles(p<.05) had higher inter-ocular FI ratios. 27% of anisometropic and >65% of strabismic/mixed amblyopes had nystagmus. Younger age and nystagmus increased FI and vergence instability(p<0.05), but did not affect the Inter-ocular FI ratios(p>0.05). 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.
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Affiliation(s)
- Fatema Ghasia
- Vision Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, 9500 Euclid Ave, Cleveland, Ohio.
| | - Lawrence Tychsen
- Department of Ophthalmology and Visual Sciences, St Louis Children's Hospital at Washington University School of Medicine, St Louis, Missouri
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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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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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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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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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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, Nucci P, Shaikh AG, Ghasia FF. Fixational eye movements abnormalities and rate of visual acuity and stereoacuity improvement with part time patching. Sci Rep 2021; 11:1217. [PMID: 33441575 PMCID: PMC7806581 DOI: 10.1038/s41598-020-79077-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 12/03/2020] [Indexed: 11/09/2022] Open
Abstract
Residual amblyopia is seen in 40% of amblyopic patients treated with part-time patching. Amblyopic patients with infantile onset strabismus or anisometropia can develop fusion maldevelopment nystagmus syndrome (FMNS). The purpose of this study was to understand the effects of presence of FMNS and clinical subtype of amblyopia on visual acuity and stereo-acuity improvement in children treated with part-time patching. Forty amblyopic children who had fixation eye movement recordings and at least 12 months of follow-up after initiating part-time patching were included. We classified amblyopic subjects per the fixational eye movements characteristics into those without any nystagmus, those with FMNS and patients with nystagmus without any structural anomalies that do not meet the criteria of FMNS or idiopathic infantile nystagmus. We also classified the patients per the clinical type of amblyopia. Patching was continued until amblyopia was resolved or no visual acuity improvement was noted at two consecutive visits. Children with anisometropic amblyopia and without FMNS have a faster improvement and plateaued sooner. Regression was only seen in patients with strabismic/mixed amblyopia particularly those with FMNS. Patients with FMNS had improvement in visual acuity but poor stereopsis with part-time patching and required longer duration of treatment.
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Affiliation(s)
- Matteo Scaramuzzi
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
- Department of Neuroscience, Unit of Ophthalmology, IRCCS Istituto Giannina Gaslini, Genoa, Italy
- DISCCO, University of Milan, Milan, Italy
| | - Jordan Murray
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | | | - Aasef G Shaikh
- Daroff-Dell'Osso Ocular Motility Laboratory, Cleveland, OH, USA
- Case Medical Center, Case Western Reserve University, Cleveland, OH, USA
| | - Fatema F Ghasia
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA.
- Case Medical Center, Case Western Reserve University, Cleveland, OH, 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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Essig P, Leube A, Rifai K, Wahl S. Microsaccadic rate signatures correlate under monocular and binocular stimulation conditions. J Eye Mov Res 2020; 11. [PMID: 33828709 PMCID: PMC8008506 DOI: 10.16910/jemr.13.5.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Microsaccades are involuntary eye movements occurring naturally during fixation. In this
study, microsaccades were investigated under monocularly and binocularly stimulated
conditions with respect to their directional distribution and rate signature, that refers to a
curve reporting the frequency modulation of microsaccades over time. For monocular
stimulation the left eye was covered by an infrared filter. In both stimulation conditions,
participants fixated a Gabor patch presented randomly in orientation of 45° or 135° over a
wide range of spatial frequencies appearing in the center of a monitor. Considering the
microsaccadic directions, this study showed microsaccades to be preferably horizontally
oriented in their mean direction, regardless of the spatial characteristics of the grating.
Furthermore, this outcome was found to be consistent between both stimulation conditions.
Moreover, this study found that the microsaccadic rate signature curve correlates between
both stimulation conditions, while the curve given for binocular stimulation was already
proposed as a tool for estimation of visual performance in the past. Therefore, this study extends the applicability of microsaccades to clinical use, since
parameters as contrast sensitivity, has been measured monocularly in the clinical attitude.
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Affiliation(s)
- Peter Essig
- Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Germany
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Impaired Saccade Adaptation in Tremor-Dominant Cervical Dystonia-Evidence for Maladaptive Cerebellum. THE CEREBELLUM 2020; 20:678-686. [PMID: 31965455 DOI: 10.1007/s12311-020-01104-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We examined the role of the cerebellum in patients with tremor-dominant cervical dystonia by measuring the adaptive capacity of rapid reflexive eye movements (saccades). We chose the saccade adaptation paradigm because, unlike other motor learning paradigms, the real-time modification of saccades cannot "wait" for the sensory (visual) feedback. Instead, saccades rely primarily on the internal reafference modulated by the cerebellum. The saccade adaptation happens over fast and slow timescales. The fast timescale has poor retention of learned response, while the slow timescale has strong retention. Cerebellar defects resulting in loss of function affect the fast timescale but the slow timescale of saccade adaptation is retained. In contrast, maladaptive cerebellar disorders feature the absence of both fast and slow timescales. We were able to measure both timescales using noninvasive oculography in 6 normal individuals. In contrast, both timescales were absent in 12 patients with tremor-dominant cervical dystonia. These findings are consistent with maladaptive cerebellar outflow as a putative pathophysiological basis for tremor-dominant cervical dystonia.
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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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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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14
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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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15
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Upadhyaya S, Pullela M, Ramachandran S, Adade S, Joshi AC, Das VE. Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys. Invest Ophthalmol Vis Sci 2017; 58:5743-5753. [PMID: 29114840 PMCID: PMC5678548 DOI: 10.1167/iovs.17-22389] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 10/02/2017] [Indexed: 12/30/2022] Open
Abstract
Purpose To evaluate the contribution of fixational saccades toward fixation instability in strabismic monkeys. Methods Binocular eye movements were measured as six experimental monkeys (five strabismic monkeys and one monkey with downbeat nystagmus) and one normal monkey fixated targets of two shapes (Optotype, Disk) and two sizes (0.5°, 2°) during monocular and binocular viewing. Fixational saccades were detected using an unsupervised clustering algorithm. Results When compared with the normal monkey, amplitude and frequency of fixational saccades in both the viewing and nonviewing eye were greater in 3 of 5 strabismic monkeys (1-way ANOVA on ranks P < 0.001; median amplitude in the normal monkey viewing eye: 0.33°; experimental animals: median amplitude range 0.20-0.82°; median frequency in the normal monkey: 1.35/s; experimental animals: median frequency range 1.3-3.7/s). Increase in frequency of fixational saccades was largely due to quick phases of ongoing nystagmus. Fixational saccade amplitude was increased significantly (3-way ANOVA; P < 0.001) but by small magnitude depending on target shape and size (mean difference between disk and optotype targets = 0.02°; mean difference between 2° and 0.5° targets = 0.1°). Relationship between saccade amplitude and the Bivariate Contour Ellipse Area (BCEA) was nonlinear, showing saturation of saccade amplitude. Fixation instability in depth was significantly greater in strabismic monkeys (vergence BCEA: 0.63 deg2-2.15 deg2) compared with the normal animal (vergence BCEA: 0.15 deg2; P < 0.001). Conclusions Increased fixational instability in strabismic monkeys is only partially due to increased amplitude and more frequent fixational saccades. Target parameter effects on fixational saccades are similar to previous findings of target effects on BCEA.
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Affiliation(s)
- Suraj Upadhyaya
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Mythri Pullela
- College of Optometry, University of Houston, Houston, Texas, United States
| | | | - Samuel Adade
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Anand C. Joshi
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Vallabh E. Das
- College of Optometry, University of Houston, Houston, Texas, United States
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16
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Shaikh AG, Ghasia FF. Novel Eye Movement Disorders in Whipple's Disease-Staircase Horizontal Saccades, Gaze-Evoked Nystagmus, and Esotropia. Front Neurol 2017; 8:321. [PMID: 28744253 PMCID: PMC5504231 DOI: 10.3389/fneur.2017.00321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 06/20/2017] [Indexed: 11/13/2022] Open
Abstract
Whipple’s disease, a rare systemic infectious disorder, is complicated by the involvement of the central nervous system in about 5% of cases. Oscillations of the eyes and the jaw, called oculo-masticatory myorhythmia, are pathognomonic of the central nervous system involvement but are often absent. Typical manifestations of the central nervous system Whipple’s disease are cognitive impairment, parkinsonism mimicking progressive supranuclear palsy with vertical saccade slowing, and up-gaze range limitation. We describe a unique patient with the central nervous system Whipple’s disease who had typical features, including parkinsonism, cognitive impairment, and up-gaze limitation; but also had diplopia, esotropia with mild horizontal (abduction more than adduction) limitation, and vertigo. The patient also had gaze-evoked nystagmus and staircase horizontal saccades. Latter were thought to be due to mal-programmed small saccades followed by a series of corrective saccades. The saccades were disconjugate due to the concurrent strabismus. Also, we noted disconjugacy in the slow phase of gaze-evoked nystagmus. The disconjugacy of the slow phase of gaze-evoked nystagmus was larger during monocular viewing condition. We propose that interaction of the strabismic drifts of the covered eyes and the nystagmus drift, putatively at the final common pathway might lead to such disconjugacy.
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Affiliation(s)
- Aasef G Shaikh
- Daroff-Dell'Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, VA, United States.,Department of Neurology, Case Western Reserve University, Cleveland, OH, United States.,Neurological Institute, University Hospitals, Cleveland, OH, United States.,Neurology Service, Louis Stokes, Cleveland, VA, United States
| | - Fatema F Ghasia
- Daroff-Dell'Osso Ocular Motility Laboratory, Cleveland VA Medical Center, Cleveland, VA, United States.,Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
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