Comparison of optic disc head vascular density status between crowded and normal discs: An optical coherence tomography angiography study.

Background: To compare the optic disc capillary vascular status between crowded and normal optic discs using optical coherence tomography angiography (OCT-A).

Methods: A total of 101 eyes were included in this cross-sectional, comparative study. Fifty-one eyes with crowded optic discs (Group 1) were compared with 50 eyes with normal discs (Group 2). Peripapillary and optic disc head capillary vascular density measurements were obtained quantitatively with OCT-A.

Results: Mean ages were 46.2 ± 6.2 years in Group1 and 45.9 ± 6.0 years in Group2 (p=0.796).Vertical disc diameters were 1.52±0.2 mm in Group 1 and 1.61±0.16 mm in Group 2 (p=0.022) whereas horizontal disc diameters were 1.53±0.17 mm in Group 1 and 1.61±0.13 mm in Group 2(p˂0.014). OCT-A findings were as follows: radial peripapillary capillary, vascular density whole image measurements (%); 49.6 ± 2.3 in Group 1 and 49.1 ± 2.3 in Group 2 (p=0.292), peripapillary capillary density; 53.3 ± 2.8 in Group 1 and 52.6 ± 2.6 in Group 2 (p=0.176), inside disc measurements 52.4 (48.7-54.7) in Group 1 and 46.5 (42.6-49.6) in Group 2 (p˂0.001). RNFL was 118.2 ± 12.2 µm in Group 1 and 110.8 ± 11.4 µm in Group 2(p=0.002).

Conclusion: The vascular density of the disc circumference in individuals with healthy crowded optic discs is not different from those with normal discs. However, inside disc measurements differ between crowded and normal size discs. This finding suggests that when the disc size is reduced, the amount of vessels in it does not decrease in a way that correlates with the size. Therefore, the vascular structures are suitable for compression in the narrow optic nerve head.