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Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement

PURPOSE: Heterophoria describes the deviation of the optical axes in the absence of binocular fusion. Eye trackers (ET) can provide an objective assessment but are not broadly used clinically. We examined the feasibility of combining an infrared (IR) pass-filter, IR detector, and an off-the-shelf ET...

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Autores principales: Gantz, Liat, Caspi, Avi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Association for Research in Vision and Ophthalmology 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414612/
https://www.ncbi.nlm.nih.gov/pubmed/32832245
http://dx.doi.org/10.1167/tvst.9.7.40
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author Gantz, Liat
Caspi, Avi
author_facet Gantz, Liat
Caspi, Avi
author_sort Gantz, Liat
collection PubMed
description PURPOSE: Heterophoria describes the deviation of the optical axes in the absence of binocular fusion. Eye trackers (ET) can provide an objective assessment but are not broadly used clinically. We examined the feasibility of combining an infrared (IR) pass-filter, IR detector, and an off-the-shelf ET. The proposed setup was validated against the broadly used cover test (CT). Furthermore, the setup was used to examine whether testing conditions can affect the measurements. METHODS: An IR detector was attached to a handheld IR-pass filter that blocks visible light to provide occlusion while passing IR light for eye tracking. The detector senses the IR illumination of the eye tracker, creating a recordable signal of the occluder position synchronized with eye positions acquired by the SMI Red250 tracker. The mean of three measurements of each condition, three versus ten seconds occlusion, the occluded eye, and ET versus CT results were compared using the Wilcoxon test, correlation and Bland and Altman plots. Differences between measurements that were within 2(Δ) were considered clinically insignificant. RESULTS: Thirty normally-sighted subjects (mean age 24.50 ± 2.20, range 20–28) with heterophoria ranging between 14(Δ) exophoria and 4(Δ) esophoria were recruited. There was no significant difference between the occluded eyes. However, there was a difference between 3 and 10 seconds’ cover duration. The CT data were more similar to the 10 seconds cover duration, although differences were less than the clinical resolution of 2(Δ). CONCLUSIONS: An inexpensive off-the-shelf ET can be used to measure heterophoria with controlled testing parameters. TRANSLATIONAL RELEVANCE: Our study demonstrated a robust technique for synchronization of an optical element such as an IR cover, with an off-the-shelf commercial eye tracker. The synchronization of optical elements with eye tracking, which has been described here for heterophoria, can be adapted for other clinical measurements.
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spelling pubmed-74146122020-08-21 Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement Gantz, Liat Caspi, Avi Transl Vis Sci Technol Article PURPOSE: Heterophoria describes the deviation of the optical axes in the absence of binocular fusion. Eye trackers (ET) can provide an objective assessment but are not broadly used clinically. We examined the feasibility of combining an infrared (IR) pass-filter, IR detector, and an off-the-shelf ET. The proposed setup was validated against the broadly used cover test (CT). Furthermore, the setup was used to examine whether testing conditions can affect the measurements. METHODS: An IR detector was attached to a handheld IR-pass filter that blocks visible light to provide occlusion while passing IR light for eye tracking. The detector senses the IR illumination of the eye tracker, creating a recordable signal of the occluder position synchronized with eye positions acquired by the SMI Red250 tracker. The mean of three measurements of each condition, three versus ten seconds occlusion, the occluded eye, and ET versus CT results were compared using the Wilcoxon test, correlation and Bland and Altman plots. Differences between measurements that were within 2(Δ) were considered clinically insignificant. RESULTS: Thirty normally-sighted subjects (mean age 24.50 ± 2.20, range 20–28) with heterophoria ranging between 14(Δ) exophoria and 4(Δ) esophoria were recruited. There was no significant difference between the occluded eyes. However, there was a difference between 3 and 10 seconds’ cover duration. The CT data were more similar to the 10 seconds cover duration, although differences were less than the clinical resolution of 2(Δ). CONCLUSIONS: An inexpensive off-the-shelf ET can be used to measure heterophoria with controlled testing parameters. TRANSLATIONAL RELEVANCE: Our study demonstrated a robust technique for synchronization of an optical element such as an IR cover, with an off-the-shelf commercial eye tracker. The synchronization of optical elements with eye tracking, which has been described here for heterophoria, can be adapted for other clinical measurements. The Association for Research in Vision and Ophthalmology 2020-06-29 /pmc/articles/PMC7414612/ /pubmed/32832245 http://dx.doi.org/10.1167/tvst.9.7.40 Text en Copyright 2020 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 Article
Gantz, Liat
Caspi, Avi
Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement
title Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement
title_full Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement
title_fullStr Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement
title_full_unstemmed Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement
title_short Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement
title_sort synchronization of a removable optical element with an eye tracker: test case for heterophoria measurement
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414612/
https://www.ncbi.nlm.nih.gov/pubmed/32832245
http://dx.doi.org/10.1167/tvst.9.7.40
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