Abstract
Purpose :
Early detection of ganglion cell (GC) loss is of paramount importance for assessing glaucoma risk and treating the disease. The resolution of clinical instruments is improving but still falls well short of that required to detect loss of individual cells, where onset and progression begin. In this study, we measured GCL soma loss rates associated with both normal aging and glaucoma using adaptive optics optical coherence tomography (AO-OCT) to image and track individual GCL somas over a 2-year period.
Methods :
One eye from each of four healthy subjects (39 ± 14 yrs old (average ± SD)) and two glaucomatous patients with arcuate defects (63 and 73 yrs old) were imaged with the Indiana AO-OCT system. In the healthy subjects, AO-OCT volumes were acquired of 1.5°×1.5° retinal patches at 7 different locations. Five locations temporal to fovea (1.5°–3°, 3°–4.5°, 6°–7.5°, 8°–9.5°, 12°–13.5°) were imaged in all four subjects and two nasal to fovea (1.5°–3°, 3°–4.5°) were imaged in one subject. In the glaucomatous patients, AO-OCT volumes were acquired within the arcuate defect. From the registered and averaged AO-OCT volumes (n ~ 150), we identified individual GCL somas, quantified their morphometric parameters (e.g., soma density), and measured the local GCL thickness. We repeated measurements one and two years later for the healthy subjects and two years later for the glaucomatous patients, tracking individual somas across measurements. We computed the annual soma loss rate (%/yr) from the number of somas lost between measurements and the number present.
Results :
Average GCL soma loss rate across the four healthy subjects and 6 retinal locations was 0.15%/yr (95% CI, 0.08–0.26%/yr), which was smaller than but consistent with that expected from normal aging 0.19%/yr (95% CI, -0.34–0.74%/yr, Curcio and Drucker, Ann Neurol. 33, 248–257(1993)). Soma loss rate was strikingly different between the two glaucomatous patients: 0.36%/yr (95% CI, 0.02–3.32 %/yr) and 39.7%/yr (95% CI, 39.3–75.1%/yr). The latter patient lost significantly more somas than the healthy subjects, and the decrease was 5X greater than the local decrease in GCL thickness (~8%/yr).
Conclusions :
GCL soma loss rates are now measurable in both healthy and glaucomatous eyes.
This is a 2020 ARVO Annual Meeting abstract.