Test-Retest Repeatability of a Novel Photopic Microperimetry Approach in Patients with Geographic Atrophy.

Purpose: To evaluate test-retest repeatability of novel focal photopic microperimetry approach targeting central 1 mm of the fovea and explore its relationships with geographic atrophy (GA) lesion area and other visual function metrics. Design: A prospective, single arm, observational study. Subjects: Participants with nonsubfoveal GA as determined by spectral-domain OCT and fundus autofluorescence. Methods: Twelve participants (17 eyes) performed focal photopic tests using a 45-loci focal grid (0.5° spacing; Goldmann II stimuli) on Nidek MP-3, along with other visual function assessments. To assess test-retest repeatability of MP-3, 2 tests up to 4 weeks apart were performed. The interval was short relative to expected GA progression, and thus measurements are interpreted as reflecting test-retest repeatability. Main Outcome Measures: Coefficient of repeatability (CoR), intraclass correlation coefficient (ICC), and Bland-Altman were analyzed for mean sensitivity (MS) and point-wise sensitivity (PWS). Correlations of adjusted MS (excluding floor effect) with GA lesion size, best-corrected visual acuity (BCVA), low-luminance visual acuity (LLVA), and contrast sensitivity were also analyzed. Results: Focal photopic MP-3 showed good test-retest repeatability with CoR of MS at 2.42 dB (intraclass correlation coefficient [ICC] = 0.98) and CoR of PWS at 8.2 dB (ICC = 0.89). Excluding the floor effect improved the CoR of MS and PWS to 2.03 dB and 7.06 dB, respectively. Mean test duration was 4.33 minutes per eye with fixation stability >89%. Structure-function analysis showed weak correlation between GA lesion size and adjusted MS ( Conclusions: Focal photopic microperimetry using Goldmann II stimuli provides a highly repeatable measure of central cone-mediated function in patients with nonsubfoveal GA. Mean sensitivity demonstrated high repeatability and supports its use as a robust, clinically relevant endpoint for longitudinal and interventional studies, while PWS may provide spatial information for deeper structure-function analyses. Weak associations with GA lesion size and BCVA suggest that conventional measures may underestimate visual impairment, highlighting the value of focal photopic microperimetry within central 1 mm region as a sensitive, patient-centered outcome in age-related macular degeneration. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.