Changes in retinal blood vessel density in primary open angle glaucoma following intra ocular pressure reduction by medical management: An optical coherence tomography angiography study

INTRODUCTION: Glaucoma is a chronic progressive optic neuropathy with characteristic disc and field changes for which raised intraocular pressure (IOP) is the only known modifiable risk factor. The pathogenesis of optic nerve damage in glaucoma is as yet not completely understood. Glaucomatous optic neuropathy is multifactorial in nature with mechanical, vascular and possible neuronal factors contributing to the damage. Vascular factors have been proposed to assume a noteworthy part as the progression of the glaucomatous damage continues in some patients in spite of adequate IOP reduction. OBJECTIVE: To document the papillary (PvD), optic nerve head (ONHvD), peripapillary (PPAvD) and macular (MvD) vascular density by Optical coherence tomography angiography (OCT-A) before and after intraocular pressure (IOP) reduction by medical management in patients with primary open angle glaucoma (POAG). METHODS: This was a prospective observational study done in the Department of Ophthalmology, Christian Medical College, Vellore. OCT-A scans for analysis of the PvD, ONHvD, PPAvD and MvD were done at baseline, 2 weeks, 1 month and 3 months after treatment. Repeated measures ANOVA was used to compare the change of variables from baseline - 3 months and posthoc analysis were performed using Tukey's test. The correlation between the change from baseline to 3 months IOP and OCV with other parameters were analyzed using Pearson's correlation. A p- value < 0.05 was considered significant. RESULTS: 24 eyes of 24 POAG patients were included. At 3 months, IOP significantly decreased (41.6%) from 24.79± 3.63 mmHg to13.58 ± 2.04 mmHg (p=