Abstract
Purpose :
The relationship between nerve fiber layer thickness (NFLT) measured by structural OCT, nerve fiber layer plexus capillary density (NFLP-CD) assessed via OCT angiography (OCTA), and mean deviation in visual field tests (VF-MD) is not linear. This study aimed to develop new metrics by integrating data from both OCT and OCTA to better correlate with visual field outcomes.
Methods :
The study included healthy controls and glaucoma patients with disc rim thinning or retinal nerve bundle defects. Disc scans were performed using a spectral-domain OCT system. NFLT and NFLP-CD measurements were divided into eight sectors, each corresponding to a specific area on the visual field map. Each sector was further divided into four evenly tracks, resulting in 32 tracks per scan. Normalized track values were converted into a logarithmic dB scale and then aggregated to obtain sector values in the dB scale. The dB-scaled-OCT and dB-scaled-OCTA were combined using multiple quadratic regression to simulate the sector visual field total deviation. Sector-simulated values were weighted and summed to derive NFL-MD, NFLP-MD, and combined-MD. A five-fold cross-validation approach was implemented to prevent overfitting.
Results :
The study included 51 eyes with perimetric glaucoma (PG), 40 with pre-perimetric glaucoma (PPG), and 41 healthy control eyes. The Pearson correlation between NFL-MD and VF-MD was notably high at 0.778 (0.700-0.838), surpassing the correlation between NFL thickness and VF-MD, 0.589 (0.465-0.690). Similarly, the correlation between NFLP-MD and VF-MD was substantial at 0.777 (0.698-0.837), exceeding the correlation between NFLP-CD and VF-MD, which was 0.646 (0.535-0.734). The correlation between combined-MD and VF-MD was 0.816(0.750-0.867), significantly better correlated with VF-MD than NFL-MD and NFLP-MD (p=0.025 for comparison with NFL-MD and p=0.003 for comparison with NFLP-MD). (Figure1)
Conclusions :
The simulated visual field tests based on OCT or OCTA demonstrated improved agreement with actual 24-2 visual field tests compared to the original NFLT and NFLP-CD. And combining both OCT and OCTA results can have a better agreement. Given their enhanced correlation with disease severity and reproducibility, these metrics may hold promise for improving glaucoma monitoring.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.