Hossein Bahrami, MD, MPH, Michele Melia, PhD, and Gislin Dagnelie, PhD. Wilmer Eye Institute, Department of Ophthalmology, School of Medicine, Johns Hopkins University, 1620 McElderry Street, # 518, Baltimore, MD 21205, 410-502-6501, hbahrami@jhsph.edu

During the last two decades computer has made a great advancement in data analysis in epidemiological studies and public health issues. In this study we measured the accuracy and reliability of personal computers (PC)-based visual function tests in follow-up of patients in a longitudinal study.

Methods: Data from 39 patients with retinitis pigmentosa (RP) enrolled in a randomized double-masked placebo-controlled trial of lutein supplementation with a crossover design was analyzed. Patients were followed up for one year and visual function tests, including visual acuity(VA) and contrast sensitivity (CS), were preformed every week using the software installed in their PCs. The results were reported to a central server using Internet. Both VA and CS were tested at 4% and 100% illumination. These visual function tests were performed every six weeks in the lab and lab as “gold standard.”

Results: The mean age of the patients was 48.3± 9.2 years with a male to female ratio of 18/22. The correlation coefficients between mean values of log MAR measured by lab and PC were 0.77 and 0.68 for standard and low illumination VA, respectively, while these coefficients for mean log CS measured with two methods were 0.89 and 0.92. These four coefficients at baseline were 0.63, .80,0.90, and 0.94, respectively.

Conclusion: It sounds that PC-based visual tests have a good correlation with lab tests and can be used particularly in longitudinal studies, where the changes in an individual rather than between individuals are important, and particularly for subjective tests like vision tests.

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