Decreased Ocular Blood Flow in Patients with Advanced Optic Nerve Cupping

Abstract

Purpose: : Previous studies have suggested that ocular blood flow may play a role in the pathogenesis of glaucoma. This study examined differences in peripappillary blood flow amongst patients with various degrees of optic nerve cupping.

Methods: : Both groups had healthy, glaucoma suspects, and glaucoma patients. We compared seventeen eyes of patients with optic nerve cupping >60% (Group A) and 45 eyes of patients with optic nerve cups <= 60%(Group B). Using images obtained from the Heidelberg Retinal Flowmeter, "pixel–by–pixel" analysis was done in an area adjacent to the optic disc with a minimum of 1600 pixels. Flow values were then divided into percentile flow and "percentage zero flow" values. Comparisons were made between groups by means of T–test.

Results: : Both groups had patients with the diagnosis of healthy normals, glaucoma suspects and glaucoma. Mean age for both groups A and B were 53 and 47 years respectively (p=0.0003). Mean IOP of group A and group B was 15.76 mmHg and 14.22 mmHg, respectively with no significant difference between groups (p>0.10). Group A showed a mean "percentage zero flow" value of 17.51% while Group B was 14.02% (p=0.01).

Conclusions: : The mean percentage zero flow was found to be significantly greater in patients with optic nerve cupping greater than 60% as compared with patients with <=60% cupping. In addition to cupping, age may also be a contributory factor to this phenomenon. It is unclear if the lack of perfusion causes the cupping or enlarged cups causes a lack of perfusion of the peripappillary retina.

Keywords: blood supply • imaging/image analysis: non-clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)