A comparative study between systemic hypertension, intraocular tension and ocular perfusion pressure in primary open angle glaucoma, normal tension glaucoma and normal population in a tertiary care centre

Introduction: Glaucoma is a chronic progressive optic neuropathy characterized by retinal ganglion cell death and associated visual field loss irrespective of intraocular pressure changes. The exact pathophysiological mechanism is not fully understood. The vascular hypothesis of OAG states that a low blood pressure (BP) relative to IOP can lead to low mean ocular perfusion pressure (MOPP), thus impairing perfusion of the Optic Nerve Head (ONH) with resultant glaucomatous cupping and visual field loss. Objective: To find out any relationship between systemic hypertension, intraocular tension (IOP) and mean ocular perfusion pressure (MOPP) in primary open angle glaucoma (POAG), normal tension glaucoma and normal population. Materials and Methods: It was a cross-sectional observational study. A total 125 patients attended in eye OPD at Calcutta National Medical College & Hospital, Kolkata, in one year having primary open angle glaucoma including normal tension glaucoma. Patients were distributed into three groups according to the technique of management. Applanation Tonometry and fundoscopic evaluation (+ 90 D lens) were done for all cases. Single recording of BP was taken. Gonioscopy, Humphrey's central visual fields and pachymetry were done. Data analyzed using standard statistical technique and a probability value (‘p' value) of < 0.05 was considered as statistically significant. Results: The average age of the study population was 54.38 ±8.92 years and ranging from 41 to 75 years. The study was male preponderant. The relationship between mean arterial pressure, intraocular pressure and mean ocular perfusion pressure was statistically significant in all subgroups. Conclusion: There was a moderately strong correlation between MAP and MOPP whereas between MAP and IOP was weakly positive. The relationship between IOP and MOPP was inversely correlated.