Association between intraocular pressure, mean blood pressure, and mean ocular perfusion pressure among normal healthy adults

Abstract

Background: On the one hand, hypertension is an independent risk factor for glaucoma; on the other hand, hypertension is protective by increasing mean ocular perfusion pressure (MOPP). Reduction in ocular perfusion pressure results in decreased blood flow to the optic nerve head hence plays a role in the pathogenesis of glaucoma. Low MOPP would result from reduction in mean blood pressure (MBP) and increase in intraocular pressure (IOP). Aim and Objective: The aim of the study was to find out the association between MBP, IOP, and MOPP in normal healthy adults. Materials and Methods: The study included 300 healthy young individuals. The BP was recorded using Mercury Sphygmomanometer and IOP recording was done using Slit lamp mounted Goldman Applanation tonometer. MBP was calculated by the formula MBP = DBP+1/3 pulse pressure. The MOPP was calculated by formula: MOPP=MBP–IOP. The subjects were divided into five groups based on the value of MBP: Group 1: 71–80 mm of Hg, Group 2: 81–90 mm of Hg, Group 3: 91–100 mm of Hg, Group 4: 100–110 mm of Hg, and Group 5: >110 mm of Hg. Results: IOP increased linearly with increase in MBP. (P < 0.001) MOPP was positively correlated with MBP in both males (r = 0.985, P < 0.001) and females (r = 0.986, P < 0.001). The MBP is positively correlated with IOP in both males (r = 0.615, P < 0.001) and females (r = 0.668, P < 0.001). Conclusion: Increased MBP is a risk factor for raised IOP as well as raised MOPP. Whether raised MOPP is protective against primary open angle glaucoma or not is still question of debate and needs further evaluation.