Distribution of Ocular Perfusion Pressure and Its Effect on Primary Open Angle Glaucoma Among Adult’s Patients at KCMC Referral Hospital 2024-2025

Abstract

Aims: To evaluate the distribution of ocular perfusion pressure and its effect on primary open-angle glaucoma among adult patients at KCMC eye department. Study Design: Case-control and cross-sectional designs. Place and Duration of Study: The study was conducted at a KCMC zonal referral hospital in Tanzania, from July 2024 to July 2025. Methodology: A total of 179 participants aged ≥40 years were included, a rebound tonometer (Icare-100) was used to measure intraocular pressure (IOP). Systolic and diastolic blood pressure (SBP and DBP) was measured with a digital automatic blood pressure monitor. The flowing formulas were used: Mean arterial pressure (MAP) = DBP + 1⁄3 (SBP − DBP) and mean ocular perfusion pressure (MOPP) = 2⁄3 (MAP - IOP), diastolic perfusion pressure (DPP) = (DBP - IOP), systolic perfusion pressure (SPP) = (SBP - IOP). The POAG diagnosis followed the internal society for Geographical and Epidemiology (ISGEO) criteria. Results: Out of 179 participants, 89 POAG patients (30 NTG, 59 HTG) and 90 controls. HTG patients were more likely to be older than 65 years, while NTG cases had a median age of 61 years (x2 = 8.92, p = 0.003). NTG patients had higher rates of smoking and diabetes (x2 = 3.85, p = 0.047 and x2= 3.23, p = 0.042, respectively), while hypertension was more common among HTG patients (p = 0.038). NTG patients showed lower mean DPP (50.9 mmHg) compared to HTG (61.0 mmHg) and controls (65.5 mmHg). Mean IOP was 20 mmHg in NTG, 14.1 mmHg in controls and 26mmHg in HTG. DPP ≤ 56 mmHg (AOR: 1.58; 95%CI: 1.08, 2.32), p= 0.019 and MOPP ≤53 (AOR: 1.23; 95%CI: 1.01, 1.51), p= 0.041 mmHg, were independently associated with NTG. Conclusion: Low DPP was significantly associated with NTG, highlighting the role of impaired ocular blood flow in its pathogenesis.