Longitudinal Microperimetric Changes of Macular Sensitivity
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Stargardt disease type 1 (STGD1) is caused by pathogenic mutations in the ABCA4 gene (OMIM 601691) and leads to atrophic-appearing macular lesions and variable loss of best-corrected visual acuity (BCVA), often from 20/20 to 20/400 or worse. A study was conducted to assess the yearly rate of change of macular function in patients with STGD1 using microperimetry.

Among the 359 eyes from 200 patients who underwent microperimetry examination graded at baseline and month 12, the mean (SD) yearly change in MS was 0.68 (2.04) dB, and deep scotoma points increased by a mean (SD) of 1.56 (5.74) points per year. The points with a sensitivity of 12 dB or higher decreased in sensitivity by a mean (SD) of 3.01 (9.84) dB. The mean (SD) yearly change in MS was not significantly different between the eyes with a grading of good or fair pattern placement at both visits and the eyes with a poor pattern placement during at least 1 visit. This cohort study of 359 eyes with ABCA4-related Stargardt disease, microperimetry mean sensitivity (0.68 dB per year) and deep scotoma points (1.56 points per year) showed a statistically significant and clinically meaningful change after 12 months.

The findings suggest that simple microperimetric measures, such as overall MS or the count of normal, relative, or deep scotomatous points, may detect functional changes during a study period of 12 months. More sophisticated analyses may specifically investigate the scotoma edge. Potentially, microperimetry may detect changes in the early stages of STGD1 before structural changes can be detected. Results from the prospective Scotopic Microperimetric Assessment of Rod Function in Stargardt Disease (SMART) study will compare scotopic microperimetric changes with mesopic microperimetry data. In this study, microperimetry was a sensitive test for detecting progression within a relatively short study period; this may be useful for future clinical trials of emerging therapies for STGD1.