Macular Degeneration Discernable Using Series of Visual Function Tests

Age-related macular degeneration (AMD) stages are primarily described by the status of ocular structures, but can visual function (VF) assessments reveal disease progression reliably? In single-center studies, chart-based tests have shown statistically significant differences in function between patients with intermediate AMD (iAMD) and control individuals. Now, a large analysis, reported in JAMA Ophthalmology, employs cross-sectional data from 18 tertiary ophthalmology centers in Europe to evaluate whether 5 readily accessible VF tools prove repeatable with good discrimination.

Because functional loss in early stage AMD is only partially-defined, the population is aging, and regulatory organizations and payers only recognize best-corrected visual acuity (BCVA) loss as a VF end point, the need for better treatment indications is urgent, say MACUSTAR investigators — a public-private research consortium. High-contrast BCVA does not account for situations of low contrast or illumination, important considerations in early AMD.

The current study evaluated the 5 function tests: BCVA, low-luminance visual acuity (LLVA), Moorfields Acuity Test (MAT), International Reading Speed Test (IReST), and Pelli-Robson Contrast Sensitivity (CS). Participants included 301 individuals, mean age 71±7 years, 290 of whom attended the 2 examinations approximately 14 days apart. For the 290, 28 were diagnosed with early-stage AMD, 167 with iAMD, 41 with late disease, and 54 were healthy volunteers. Results of this analysis demonstrated solid repeatability to identify no AMD and iAMD, but limited discriminatory power for this progression.

The study found intraclass correlation coefficients (ICCs) reflecting all VF tests and participants ranged from 0.88 for the CS assessment, up to 0.96 for BCVA, indicating “good to excellent repeatability.” The CS mark of 0.90 was just under excellent. Investigators gauged discrimination with receiver operating characteristic curves for VF tests on day 0 as baseline data; and day 14, validation data. By disease stage, all 5 offered exceptional discrimination between the iAMD and late AMD groups, but had trouble discerning between comparably aged control participants and those with iAMD.

Specifically, in mean AUC values, all VF tests displayed high discrimination between iAMD and late AMD (0.92-0.99), but had indistinct results between early and intermediate AMD (0.54-0.64). CS distinguished best from no AMD to iAMD (0.77); and MAT, LLVA, and BCVA offered fair distinction (0.69-0.71). Small-print and large-print IReST poorly distinguished between no AMD and iAMD (0.57-0.61). Combining CS and LLVA offered slightly better AUC than CS alone, with higher discrimination (0.73-0.86)

Prior single-center analyses using CS tests have found good discrimination between no AMD and iAMD groups, or no AMD and nonadvanced AMD cohorts (AREDS grade 1 to 4 simplified scale). The current investigation is first to gather repeatability data for MAT and IReST in iAMD, and to demonstrate all 5 tests provide repeatability in multi-center research.

The design did not randomize test order, which may limit results. Also, no IReST in Danish is available. Technicians were unmasked to AMD group assignment, but only 5 sites enrolled participants of varying stages. This study adds data toward a larger effort. International experts are working to establish consensus on OCT classification. “It will be critical to determine whether VF measures or combinations of VF and structural measures offer better discrimination between disease stages,” the study explains.

Disclosures: Multiple study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 

Reference

Dunbar HMP, Behning C, Abdirahman A, et al. Repeatability and discriminatory power of chart-based visual function tests in individuals with age-related macular degeneration: a MACUSTAR study report. JAMA Ophthalmol. Published online June 23, 2022. doi:10.1001/jamaophthalmol.2022.2113