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Graham Brown, Sarah Swain, Gary S Rubin; Predicting Low Vision Aid Magnification In Age-Related Macular Degeneration Patients. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4791.
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To establish which clinical measures of visual performance are the best predictors of prescribed low vision aid magnification in age-related macular degeneration (ARMD) patients.
147 participants (87 female, 60 Male), average age 80.9 (range 58 - 94) were selected from AMD clinics. Participants had no ocular co-morbidity other than early cataracts, and were fluent in English with no cognitive impairment.<br /> Tests included Bailey-Lovie logMAR near acuity sentences (Near VA) and ETDRS distance Acuity, MARS contrast sensitivity, MNRead and IREST reading performance. All participants received a standard NHS hospital low vision assessment. Low vision aids were then dispensed and training in their use was provided. The dioptric power of the dispensed aids was recorded. Bivariate and multivariate regression was used to determine the best predictors of magnification dispensed.
VA ranged from 0.30 - 1.30 logMAR, mean 0.70 logMAR in the better eye. Magnification dispensed ranged from 3.50D - 56.00D with a mean of 20.00D. The strongest predictors of magnification dispensed were Near VA, accounting for 40% of the variance and MNRead acuity, accounting for 36% of the variance (both p < 0.0001). Other significant predictors were MNRead Critical Print Size, MNRead Reading Speed, distance binocular VA and Contrast Sensitivity. However, each predictor accounted for less than 25% of the variance. In the multiple regression model Near VA accounted for 40% of the variance and none of the other variables were independently associated with magnification.
The results suggest that the main predictors of magnification are Near VA and MNRead VA, in agreement with previous findings (1). This suggests that both measures could be used as clinical guidelines to dispensing magnification aids. Further research should be undertaken as to whether these results generalise to low vision patients with other eye conditions.
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