Abstract
Purpose :
To evaluate the effect of aging on estimated retinal ganglion cell (RGC) counts over time in healthy eyes.
Methods :
This longitudinal observational cohort study involved 100 healthy eyes of 50 subjects with an average follow-up of 3.5 ± 2.4 years. Estimated RGC counts were obtained by a previously described method using standard automated perimetry (SAP) sensitivity thresholds and optical coherence tomography (OCT) retinal nerve fiber layer thickness measurements by Medeiros et al. (Am J Ophthalmol. 2012; 154:814-824). Linear mixed-effects models were applied to investigate the relationship between age and rates of change in estimated RGC counts over time. Analyses were also performed adjusting for baseline age, OCT signal strength, and axial length.
Results :
The mean age at baseline was 49.6 ± 15.7 years, ranging from 22.8 to 89.9 years. 33 (66%) patients were female and 11 (22%) self-identified as Black. At baseline, eyes had an average estimated RGC count of 1,144,010 ± 222,084 cells. Over time, the rate of change in estimated RGC count was -6,284 (95% CI: -10,804 to -1,764 RGC/year; P=0.006). After adjusting for confounding factors, the effect of time on the rate of estimated RGC loss was -6,533 RGC/year (95% CI: -11,088 to -1,979 RGC/year; P = 0.005), or an equivalent of an average loss in RGC over time of 0.5%/year.
Conclusions :
Our study has demonstrated a significant age-related decline in estimated RGC counts in healthy subjects, obtained from combining information from structural and functional tests. After accounting for confounding factors, the age-related decline was comparable to those obtained in previous histologic studies reported on the literature, ranging from 0.3% and 0.6% per year. Normal aging should be considered when estimating RGC counts over time to differentiate between pathological and nonpathological losses.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.