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Objective estimation of visual Acuity with preferential looking


Sturm, V; Cassel, D; Eizenman, M (2011). Objective estimation of visual Acuity with preferential looking. Investigative Ophthalmology and Visual Science, 52(2):708-713.

Abstract

Purpose: A novel Preferential Looking (PL) procedure that uses quantitative analysis of visual scanning parameters is presented.

Methods: Nine adult subjects were presented with a set of 14 visual stimuli (stimuli included 3 uniform grey fields and 1 field with black and white square wave gratings) spanning the range of spatial frequencies from 1.5 cycles/degree to 35.1 cycles/degree (1.3 logMAR to -0.07 logMAR). A remote gaze-tracking system was used to monitor the subject's eye movements and the relative fixation time (RFT) on the grating target. Subsequently, a four alternative forced-choice psychophysical test (4AFC) was performed with the same visual stimuli.

Results: For visual stimuli for which the gratings' positions in the 4AFC test were identified correctly in 100% of the trials ("reliably discriminated"), the mean RFT was 72.5% ± 9.0%. For stimuli for which the spatial frequencies were higher than the subject's psychophysically determined VA threshold ("non-discriminated"), the mean RFT was 25.3% ± 8.5%. Using three repeated trials at each spatial frequency and a VA detector that is based on the conditional probability density functions of the RFT, the average VA was underestimated by 0.06 logMAR (range: 0.00 logMAR to 0.20 logMAR).

Conclusions: In adults, automated quantitative analysis of visual scanning patterns can be used to estimate objectively and rapidly (210 seconds) VA with a mean error of 0.06 logMAR. The novel approach may form the basis for PL procedures that are more objective and accurate than the traditional clinical PL procedures.

Purpose: A novel Preferential Looking (PL) procedure that uses quantitative analysis of visual scanning parameters is presented.

Methods: Nine adult subjects were presented with a set of 14 visual stimuli (stimuli included 3 uniform grey fields and 1 field with black and white square wave gratings) spanning the range of spatial frequencies from 1.5 cycles/degree to 35.1 cycles/degree (1.3 logMAR to -0.07 logMAR). A remote gaze-tracking system was used to monitor the subject's eye movements and the relative fixation time (RFT) on the grating target. Subsequently, a four alternative forced-choice psychophysical test (4AFC) was performed with the same visual stimuli.

Results: For visual stimuli for which the gratings' positions in the 4AFC test were identified correctly in 100% of the trials ("reliably discriminated"), the mean RFT was 72.5% ± 9.0%. For stimuli for which the spatial frequencies were higher than the subject's psychophysically determined VA threshold ("non-discriminated"), the mean RFT was 25.3% ± 8.5%. Using three repeated trials at each spatial frequency and a VA detector that is based on the conditional probability density functions of the RFT, the average VA was underestimated by 0.06 logMAR (range: 0.00 logMAR to 0.20 logMAR).

Conclusions: In adults, automated quantitative analysis of visual scanning patterns can be used to estimate objectively and rapidly (210 seconds) VA with a mean error of 0.06 logMAR. The novel approach may form the basis for PL procedures that are more objective and accurate than the traditional clinical PL procedures.

Citations

7 citations in Web of Science®
5 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Ophthalmology Clinic
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2011
Deposited On:24 Dec 2010 09:08
Last Modified:05 Apr 2016 14:24
Publisher:Association for Research in Vision and Ophthalmology
ISSN:0146-0404
Publisher DOI:10.1167/iovs.09-4911
PubMed ID:20861485
Permanent URL: http://doi.org/10.5167/uzh-38383

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