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Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys
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 sha...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Association for Research in Vision and Ophthalmology
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5678548/ https://www.ncbi.nlm.nih.gov/pubmed/29114840 http://dx.doi.org/10.1167/iovs.17-22389 |
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author | Upadhyaya, Suraj Pullela, Mythri Ramachandran, Santoshi Adade, Samuel Joshi, Anand C. Das, Vallabh E. |
author_facet | Upadhyaya, Suraj Pullela, Mythri Ramachandran, Santoshi Adade, Samuel Joshi, Anand C. Das, Vallabh E. |
author_sort | Upadhyaya, Suraj |
collection | PubMed |
description | 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 deg(2)–2.15 deg(2)) compared with the normal animal (vergence BCEA: 0.15 deg(2); 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. |
format | Online Article Text |
id | pubmed-5678548 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | The Association for Research in Vision and Ophthalmology |
record_format | MEDLINE/PubMed |
spelling | pubmed-56785482017-11-13 Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys Upadhyaya, Suraj Pullela, Mythri Ramachandran, Santoshi Adade, Samuel Joshi, Anand C. Das, Vallabh E. Invest Ophthalmol Vis Sci Eye Movements, Strabismus, Amblyopia and Neuro-Ophthalmology 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 deg(2)–2.15 deg(2)) compared with the normal animal (vergence BCEA: 0.15 deg(2); 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. The Association for Research in Vision and Ophthalmology 2017-11 /pmc/articles/PMC5678548/ /pubmed/29114840 http://dx.doi.org/10.1167/iovs.17-22389 Text en Copyright 2017 The Authors http://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. |
spellingShingle | Eye Movements, Strabismus, Amblyopia and Neuro-Ophthalmology Upadhyaya, Suraj Pullela, Mythri Ramachandran, Santoshi Adade, Samuel Joshi, Anand C. Das, Vallabh E. Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys |
title | Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys |
title_full | Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys |
title_fullStr | Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys |
title_full_unstemmed | Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys |
title_short | Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys |
title_sort | fixational saccades and their relation to fixation instability in strabismic monkeys |
topic | Eye Movements, Strabismus, Amblyopia and Neuro-Ophthalmology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5678548/ https://www.ncbi.nlm.nih.gov/pubmed/29114840 http://dx.doi.org/10.1167/iovs.17-22389 |
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