The Relationship Between Changes in Ocular Perfusion Pressure and Retinal Nerve Fiber Layer Thickness in Patients With Glaucoma

Abstract

Purpose: To investigate the relationship between changes in ocular perfusion pressure, retinal nerve fiber layer (RNFL) thickness and optic nerve head structure after one year in patients with open angle glaucoma (OAG). Methods: Seventy six patients (age 67.7, 43 females) with OAG participating in the Indianapolis Glaucoma Progression Study (IGPS) were evaluated after one year for changes in intraocular pressure, (IOP), ocular perfusion pressure, RNFL thickness and optic nerve head structure. RNFL thickness, cup to disc (C/D) ratio and rim area were measured by optical coherence tomography (OCT) (Stratus 4, Zeiss). Ocular perfusion pressures (systolic, diastolic and mean) were calculated after measuring IOP by applanation tonometry and blood pressure using an automated sphygmomanometer. The change from baseline to one year was calculated for each parameter and Pearson correlation analysis examined the relationship between IOP, ocular perfusion pressures and OCT structure parameters. P <0.05 were considered statistically significant. Results: Change in RNFL thickness in the temporal region was positively correlated with mean perfusion pressure and ocular perfusion pressure (r=0.209, p=0.07; r=0.202, p=0.81), respectively. There was a statistically significant positive correlation between the change in IOP and C/D horizontal ratio (r=0.235, p=0.041). Changes in IOP and the change in C/D area ratio was positively correlated while there was a negative correlation between the change in IOP and the change in rim area (r=0.20, p=0.091; r=-0.21, p=0.074), respectively. Conclusions: Ocular perfusion pressures were positively associated with RNFL thickness in patients with OAG after one year. Increased IOP was associated with increased C/D ratios and decreased rim area. Both IOP and ocular perfusion pressure are related to structural changes in patients with OAG.