Further evidence of heterogeneous visual function deficits in intermediate AMD. A MACUSTAR study report.

Abstract

Purpose : Having shown heterogeneous visual function (VF) deficits in 73% of those with intermediate age-related macular degeneration (iAMD) in the MACUSTAR cross-sectional study, we wished to investigate whether this finding could be corroborated with baseline longitudinal MACUSTAR data.

Methods : All longitudinal participants with structurally (Beckman) defined iAMD performed a battery of VF assessments: best-corrected visual acuity (BCVA); low luminance visual acuity (LLVA); Moorfields acuity chart (MA); Pelli-Robson contrast sensitivity (CS); International Reading Speed Test (IReST); average threshold from mesopic and scotopic fundus-controlled perimetry (mAT and sAT; Macular Integrity Assessment, iCare, Finland) and rod intercept time (RIT) from dark adaptometry (AdaptDx, Lumithera, USA). iAMD VF data were dichotomized against one-sided normal reference limits (95^th or 5^th percentile) defined for each test based on MACUSTAR no AMD cross-sectional data. With 8 tests, 33% of iAMD participants would be expected to exceed at least 1 reference limit by chance under the null hypothesis that their VF is equivalent to those with no AMD.

Results : 585 participants with iAMD (67% female, mean [SD] age 72 ± 7 years) and 56 with no AMD (59% female, 68 ± 6 years) were included. Reference limits for each test were BCVA:>0.10 LogMAR; LLVA:>0.32 LogMAR; MAT:>0.55 LogMAR; CS:<1.49 LogCS; IReST:<100 wpm; mAT:<21.9dB; sAT:<17.1 dB and RIT:>6.13 mins. 413 participants with iAMD (71%) exceeded the reference limits on at least one VF test. 258 (44%) exceeded the reference limits on at least two VF tests. The proportion of those with iAMD exceeding normal reference limits was largest for CS (31%) and RIT (31%) and lowest for IReST (13%).

Conclusions : 71% of those with structurally defined iAMD exhibited deficits in VF tests falling outside normal reference limits; more than two-fold greater than that expected by chance, thus corroborating cross-sectional MACUSTAR findings. Stronger evidence of VF heterogeneity in iAMD may be relevant to inclusion criteria for trials of new therapies aiming to halt or slow photoreceptor damage. It remains to be seen whether participants with iAMD and VF deficits are more likely to progress to late AMD, or whether these findings reflect various stages of progression within iAMD. This will be established when future longitudinal MACUSTAR data is available.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.