Investigation of the Peripapillary Choriocapillaris in Normal Tension Glaucoma, Primary Open-angle Glaucoma, and Control Eyes

Precis: The peripapillary choriocapillaris (CC) was observed to be significantly impaired in normal tension glaucoma (NTG) subjects compared with normal controls using optical coherence tomography angiography (OCTA). Purpose: The aim was to quantitatively evaluate the peripapillary CC in NTG, primary open-angle glaucoma (POAG), and control eyes using OCTA. Materials and Methods: Ninety eyes (30 controls, 30 NTG, and 30 POAG) from 73 patients were imaged using the Zeiss Plex Elite 9000. Five repeat 3x3 mm OCTA scans were acquired both nasally and temporally to the optic disc and subsequently averaged. Four CC flow deficit (FD) measures were calculated using the fuzzy C-means approach: FD density (FDD), mean FD size (MFDS), FD number (FDN), and FD area (FDA). Results: Temporal NTG CC parameters were associated with visual field index and mean deviation (P<0.05). The control group showed a significantly lower nasal FDD (nasal: 3.79 +/- 1.26%, temporal: 4.48 +/- 1.73%, P=0.03), FDN (nasal: 156.43 +/- 38.44, temporal: 178.40 +/- 45.68, P=0.02), and FDA (nasal: 0.22 +/- 0.08, temporal: 0.26 +/- 0.10, P=0.03) when compared with temporal optic disc. The NTG group showed a significantly higher FDD (NTG: 5.04 +/- 2.38%, control: 3.79 +/- 1.26%, P=0.03), FDN (NTG: 185.90 +/- 56.66, control: 156.43 +/- 38.44, P=0.04), and FDA (NTG: 0.30 +/- 0.14 mm(2), control: 0.22 +/- 0.08 mm(2), P=0.03) nasal to the optic disc compared with controls. Conclusions: Association between CC parameters and glaucoma severity in NTG, but not POAG subjects, suggests vascular abnormalities may be a potential factor in the multifactorial process of glaucoma damage in NTG patients.