Stage at Initial Presentation, Management and Factors Associated with Progression among Primary Open-angle Glaucoma Patients Treated at a Tertiary Hospital in Tanzania

Abstract

Objective: To assess the stage of Primary Open Angle Glaucoma (POAG) at diagnosis, determine the proportion of patients experiencing disease progression, and identify factors influencing progression. Methods: In this retrospective cohort, 201 newly diagnosed POAG patients aged 18 years and older, each with a minimum of five Humphrey 24-2 SITA standard visual field tests (VFTs) taken at six month intervals undergoing treatment  were enrolled, for a total of 363 eyes. Disease severity was classified based on visual field mean deviation (MD) as mild (MD > -6 dB), moderate (MD -6 to -12 dB), advanced (MD -12 to -20 dB), or severe (MD < -20 dB). The primary outcome was POAG progression defined as an annual VFI deterioration of ≤ -1% per year. Kaplan Meier survival analysis was used to estimate the probability of progression, while Cox regression analysis identified factors associated with disease progression. Results: At diagnosis, 228 eyes (62.8%) had mild to moderate POAG and 135(37.2%) had advanced to severe POAG. At an average of 6 years follow up, 140 eyes (38.6%) showed progression, with a mean VFI decline of -2.2% per year. 108 of 140 eyes (77.1%) progressed to advanced and severe stages. Uncontrolled elevated intraocular pressure strongly predicted disease progression (p < 0.001), and eyes with IOP above target values had a 4.3 times higher risk of progression. Other significant risks included severe disease stage, normal tension glaucoma, and myopia, while frequent follow ups and trabeculectomy were protective. Conclusion: A significant proportion of POAG patients progressed to advanced stages. Elevated IOP was a strong predictor of progression, with a 4.3 fold increased risk when target IOP was not achieved. Regular follow ups and trabeculectomy reduced the risk of progression.These findings emphasize the importance of achieving target IOP, ensuring regular follow up, and considering early surgical intervention to prevent POAG progression and associated vision loss.