Abstract
Purpose :
Structural loss often precedes functional loss in cases of primary open-angle glaucoma, thus driving the importance of early detection and monitoring. While established correlations between structure and function in glaucomatous eyes have been studied in various modalities (particularly in traditional narrow field of view (FOV) cameras which assume a constant pixel to distance mapping), it is vital to establish these correlations in widefield (WF) cameras which are widely available, and have not yet been assessed.
Methods :
A WF slit-scanning ophthalmoscope (CLARUS™ 500, ZEISS, Dublin, CA) and automated perimeter (HFA3 Model 860 perimeter, ZEISS, Dublin, CA) were used to acquire color fundus photography images and perimetric data respectively. Both healthy (10 eyes, avg. age 56.4 ± 8.9, 44.3 – 73.1 years) and glaucomatous (14 eyes, avg. age 72.5 ± 9.3, 60.9 – 97.9 years) subjects were used as part of a retrospective analysis. Mean deviation (MD) from 24-2 SITA Standard (SS) visual fields (VFs) (extracted from 24-2C) were used to assess global function. Due to the use of a 90° FOV camera, the constant distance assumptions on narrow FOV cameras are not held. The automated measurements with manual annotations are tracked internally. Cup to disc ratios (CDR) from three independent/blind graders were computed and averaged from manual annotations using the default caliper measurement tool in CLARUS software to annotate horizonal and vertical cup and disc lengths; both ratios (hCDR and vCDR) were compared to 24-2 MDs using Spearman correlations.
Results :
Structure/functional correlations were observed for both hCDR (ρ = -0.46) and vCDR (ρ = -0.61) measurements as compared with 24-2 MDs. In Fig 1, glaucomatous eyes prove less consistent as compared with normals. Consistent with literature, this study showed CDRs using the standard measurement tool in CLARUS are larger in glaucomatous eyes.
Conclusions :
This study demonstrated a capability of providing structure/function comparisons using a WF fundus imager and perimeter. This measurement technique could be useful for enhancing research in the field of glaucoma. The study also confirms the trend that in the early to medium/advanced stages of glaucoma, the vCDR has a stronger correlation than hCDR and that vCDR is traditionally more useful in determining glaucoma severity.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.