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Objective estimation of visual acuity with preferential looking.
MedLine Citation:
PMID:  20861485     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
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 three uniform gray fields and one field with black-and-white square wave gratings) spanning the range of spatial frequencies from 1.5 cyc/deg to 35.1 cyc/deg (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 visual acuity (VA) threshold (nondiscriminated), the mean RFT was 25.3% ± 8.5%. Using three repeated trials at each spatial frequency and a VA detector based on the conditional probability density functions of the RFT, the average VA was underestimated by 0.06 logMAR (range, 0.00-0.20 logMAR). Conclusions. In adults, automated quantitative analysis of visual scanning patterns can be used to estimate VA objectively and rapidly (210 seconds) with a mean error of 0.06 logMAR. The novel approach may form the basis for PL procedures that are more objective and more accurate than the traditional clinical PL procedures.
Authors:
Veit Sturm; Daniel Cassel; Moshe Eizenman
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Publication Detail:
Type:  Journal Article     Date:  2011-02-03
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  52     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2011  
Date Detail:
Created Date:  2011-02-04     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  708-13     Citation Subset:  IM    
Affiliation:
Department of Ophthalmology and Visual Sciences, The Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada;
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