Abstract
Purpose :
Retinal pigment epithelium lipofuscin and melanolipofuscin (L/ML) gives rise to fundus autofluorescence, which normally increases throughout life and decreases markedly in advanced AMD. Age-related lens opacification reduces light transmission and introduces intrinsic autofluorescence into the light path, thus impacting signal strength. We utilized qAF to investigate L/ML-attributed autofluorescence in eyes with and without early or intermediate AMD, stratified by lens status, in a large cohort of older adults.
Methods :
Participants in the ALSTAR2 baseline cohort (NCT04112667) were assessed by the AREDS grading system for color fundus photography. As described (PMID 32855849), qAF images captured using a scanning laser ophthalmoscope and internal fluorescent reference underwent a quality review. Mean qAF intensity values in an 8-segment annulus (inner-outer radii, 9°-11°) centered on the fovea (qAF8) were analyzed with custom FIJI plugins. Pseudophakic eyes were assigned an age of 20 years. Generalized estimating equations were used to evaluate differences in qAF8 by disease status and severity and lens status.
Results :
Out of 460 individuals (mean age 72.0 ± 5.9 years, 60% female and 40% male, mean best corrected visual acuity 0.031 LogMAR), 836 eyes were classified as normal (410, 49%), early AMD (eAMD, 250, 29%), and intermediate (iAMD, 176, 21%). Among all eyes, qAF8 differed by lens status (qAF8, median (IQR): phakic 241.0 (198.6-291.1); pseudophakic 208.6 (170.9-257.6); p=0.0009). Additionally, qAF8 differed significantly by AMD presence and severity (mean qAF8: normal 244.1, eAMD 229.8, iAMD 211.4; p=0.0015). When stratified by lens status, this difference remained in phakic eyes (mean qAF8 normal 256.7, eAMD 247.9, iAMD 221.2; p=0.0013) but not in pseudophakic eyes (mean qAF8 normal 228.5, eAMD 211.6, iAMD 205.3; p=0.0974).
Conclusions :
In a large cohort, qAF8 was associated with AMD presence and severity in phakic but not pseudophakic eyes, being higher on average in phakic eyes. Unaccounted variation in individual lens density and autofluorescence may explain the association of qAF8 with AMD in phakic eyes. Future studies using qAF in older patients should enroll pseudophakic eyes for best results. Loss of histologic L/ML signal before atrophy in AMD tissues may be undetectable by current qAF.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.