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Yi-Zhong Wang, Yu-Guang He, Gina Mitzel, Song Zhang, Michael B Bartlett; Compliance and Test Variability of Patients with Maculopathy in Using an iPhone-Based Shape Discrimination Hyperacuity Test at Home. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5602.
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We reported previously in a cross-sectional study that a mobile shape discrimination hyperacuity (SDH) test was comparable to PC-based testing method and correlated with the severity of maculopathy (IOVS, 54:5497, 2013). In this study, we assessed the compliance and test variability of patients with diabetic retinopathy (DR) and age-related macular degeneration (AMD) in using the mobile SDH test at home.
A 6-month longitudinal study was conducted in 35 DR and 9 AMD patients with various degrees of maculopathy (visual acuity 20/100 or better in at least one eye). The mobile SDH test was implemented on the iOS platform using a spatial 3-alternative forced-choice staircase paradigm (IOVS, 54:5497, 2013). Each SDH measure was the average of test and retest. After being trained at the baseline visit, each patient was provided with an iPod Touch and was instructed to take the mobile SDH test at least once a week at home (unsupervised self-testing). In addition, the patients also performed supervised self-testing at 3 office visits during the study.
Thirty-five patients completed the study, while 9 DR patients were withdrawn from the study or lost to follow-up. For the DR patients who completed the study (n=26), the mean±SD weekly compliance rate was 80%±21%, and the number of measures taken in the week compliant was1.6±1.2. In comparison, the weekly compliance rate of AMD patients (n=9) was 97%±6%, and the number of measures taken was 2.0±1.4 per week. The mean-squared differences between the unsupervised test and retest were 0.019 logMAR±0.005, which was worse than the mean-squared differences between the supervised test and retest (0.014±0.008, p=0.025). Most patients had no or minimal disease condition change during the study period. The average standard deviation (test variability) of SDH measurements over 6 months was 0.098 logMAR±0.025SD for the eyes (n=44) without clinically significant change of disease condition.
This study demonstrated that the patients with maculopathy had a high compliance for visual function self-testing at home. The test variability of SDH was comparable to that of visual acuity (Am J Ophth 135:194, 2003). Future longitudinal studies are needed to assess the sensitivity and specificity of the mobile SDH test to detect visual function changes associated with disease conditions.
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