Structural biomarkers of abnormal dynamic and static rod function in the MACUSTAR baseline dataset

Abstract

Purpose : To determine whether structural biomarkers of age-related macular degeneration (AMD) vary between those with ‘normal’ and ‘abnormal’ rod function in the MACUSTAR baseline dataset.

Methods : Subjects with early(e) and intermediate(i) AMD underwent baseline tests including mesopic and scotopic fundus-controlled perimetry average threshold (mAT and sAT; icare), dark adaptation rod intercept time (RIT; AdaptDX), and multimodal imaging. Functional data were dichotomized against one-sided normal reference limits (95^th/5^th percentile) defined for each test based on MACUSTAR no AMD cross-sectional data. Proportions of people showing specific structural markers of AMD (pigmentary abnormalities, reticular pseudodrusen [RPD], incomplete/complete retinal pigment epithelial and outer retinal atrophy [iRORA/cRORA]) were compared between those with ‘normal’ and ‘abnormal’ function.

Results : From 620 subjects [eAMD (n=34), iAMD (n = 586)] who completed the baseline visit, 447 RIT (72%), 589 mAT (95%) and 564 (91%) sAT tests were valid. In pooled valid eAMD/iAMD data, 187 (42%) RIT, 127 (22%) mAT, and 116 (21%) sAT tests were abnormal (proportion higher for RIT than for either mAT or sAT [p<0.0001]). This remained the case when abnormal results were considered as a proportion of 619 total possible tests (30% RIT, 20% mAT, 19% sAT, p<0.0001). There was no significant difference in the proportion of abnormal tests between mAT and sAT (p>0.05). 417 participants produced a valid result for all three tests, of which 187 (45%) were normal and 35 (8%) abnormal for all 3 tests. 111 (27%), 13 (3%) and 16 (4%) were abnormal for RIT, mAT or sAT only, respectively, and 28 (7%) were abnormal for both mAT and sAT. A higher proportion of those with abnormal RIT (39%) than normal RIT (15%) had RPD (p<0.0001). Being abnormal for mAT or sAT was associated with increased prevalence of RPD, iRORA, cRORA and refractile deposits (p<0.05). sAT abnormality was also associated with increased prevalence of pigmentary abnormality (p=0.02).

Conclusions : Presence of e/iAMD was more strongly associated with a deficit in dynamic rod function (RIT) than static functional measures (mAT and/or sAT); there was no significant difference between mAT and sAT. The presence of RPD was strongly associated with abnormal function in all three tests, whilst other structural biomarkers were associated only with abnormality in the static functional tests.

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