Abstract
Purpose :
Adaptive optics optical coherence tomography (AO-OCT) has the potential to transform how glaucoma progression is assessed by measuring the loss of individual ganglion cells. Here, we investigate the use of AO-OCT to resolve ganglion cell layer (GCL) soma loss spatially and temporally in the arcuate defect of glaucoma subjects.
Methods :
We used the Indiana AO-OCT system to acquire volume images (1.5°x1.4°) in one eye of each of three glaucomatous patients (P1-P3, 69 ± 7.2 yrs old (average ± SD)) at several contiguous retinal locations traversing into the arcuate defect (2-7° inferior-nasal to the fovea). All locations were reimaged at one or two follow-up visits 2-6 years later. Patients had either primary open-angle (P1 and P2) or low-tension (P3) glaucoma and had focal glaucomatous arcuate damage identified using clinical OCT and visual fields. Clinical diagnosis stages spanned from moderate to severe. 4-5 subregions were selected for analysis from the AO-OCT images that sampled into the arcuate defect and overlapped between all visits. GCL soma centers were identified and their positions were marked manually in three dimensions. Soma counts were compared across visits to determine annual loss rate (%/yr). A chart review was performed to determine clinical progression of the disease and to compare against AO-OCT metrics.
Results :
Annual loss rates —averaged across all retinal subregions and visits— were 3.41% (P1), 4.14% (P2), and 22.45% (P3), all exceeding the expected loss rate due to aging (0.15 %/yr) by 23-150X. Loss rates varied by up to 2X across subregions for P1 and P2 and up to 5X for P3. These large differences suggest distinct patterns of cellular level disease progression across the arcuate defect and glaucoma patients. For subregions tracked over three visits, annual soma loss rates between imaging sessions varied with progression, stopping in only one subregion in the center of the arcuate defect. Disease progression was only detected clinically in the patient with the most severe GCL soma loss (P3).
Conclusions :
We used AO-OCT to measure subclinical loss of GCL somas in two of three glaucoma patients. The loss in all three exceeded that expected due to aging by 1-2 orders of magnitude and varied significantly among patients, retinal locations, and visits.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.