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Test-Retest Repeatability of a Novel Photopic Microperimetry Approach in Patients with Geographic Atrophy
Neha R Tandon1, Eric Vasquez1, Karl G Csaky1
1Retina Foundation of the Southwest, Dallas, Texas.
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 (P = 0.05; R 2 = 0.44). Adjusted MS showed a significant correlation with LLVA (P = 0.001) and low-luminance quick contrast sensitivity function (qCSF) (P = 0.01), a weak association with qCSF (P = 0.05), but no correlation with BCVA.
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.
