Validation of smartphone based visual acuity charts for community outreach programs.

Muhammad Rizwan Shehzad, Imran Ahmad


INTRODUCTION: Smartphones are gaining importance in all fields of health. If installed in these smartphones, these visual acuity charts could be of use in remote areas because these are handy and can be carried easily.

OBJECTIVE: Primary aim of this study was to find the accuracy of these charts in comparison to clinically used Snellen’s visual acuity charts.

METHODS: Visual acuity of a total of 100 patients was assessed on standard Snellen’s visual acuity chart at a distance of 6 meter and results were compared by checking visual acuity through smartphone installed application of Snellen’s chart at distance of 3 meters. Letter size for this chart was kept 44 mm and brightness of smartphone was maximum at the time of testing.

RESULTS: Final comparison of Snellen’s visual acuity chart named Rest vision chart with clinical Snellen’s chart resulted in no significant difference between these two charts. Mean difference of clinical Snellen’s chart of 100 patients was 1.62 while the mean difference of Rest Snellen’s vision chart was 1.65.

CONCLUSION: The study demonstrates that this Rest Snellen’s vision chart is valid and quite accurate and can be used for screening purposes for community outreach programs if letter size is 44mm and is tested at distance of 3 meters keeping the brightness of smartphone maximum.

KEYWORDS: Smart-phone, Visual acuity, Rest vision chart, Snellen’s visual acuity.

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