Predictors of Glaucoma Conversion in an African Ancestry Cohort: A Longitudinal Study

Abstract

Purpose: To identify risk factors associated with conversion from glaucoma suspect to primary open-angle glaucoma (POAG) in individuals of African ancestry.

Design: Prospective case-control study.

Subjects: A total of 330 glaucoma suspects from the Primary Open-Angle African American Glaucoma Genetics study with a median follow-up of 6.71 (IQR: 3.73-9.72) years. Participants were recruited from ophthalmology clinics in Philadelphia between July 2010 and August 2024.

Methods: Participants were classified as glaucoma suspects using quantitative adaptations of the American Academy of Ophthalmology definition if they met at least one of the following criteria: (1) elevated intraocular pressure (IOP), (2) suspicious optic nerve head or retinal nerve fiber layer (RNFL) appearance, or (3) suspicious visual field results. POAG was defined as the development of characteristic glaucomatous optic nerve damage with corresponding visual field defects. Demographic, clinical, and ocular parameters were measured at baseline and during follow-up examinations.

Main outcome measures: Conversion from glaucoma suspect to POAG. Risk factors were assessed using univariable and multivariable Cox proportional hazard models.

Results: During the follow-up period, 45 (13.6%) out of 330 glaucoma suspects converted to POAG cases. In multivariate analysis, 3 factors were significantly associated with increased risk of POAG conversion: elevated IOP (≥21 mmHg) (HR: 2.49, 95% CI: 1.20-5.17; P = .01), absence of hypertension (HR: 2.40, 95% CI: 1.18-4.85; P = .02), and presence of myopia (≤-0.5D) (HR: 2.35, 95% CI: 1.08-5.14; P = .03). Univariate analysis revealed associations between RNFL characteristics and conversion risk, including greater inter-eye difference in RNFL thickness.

Conclusions: In glaucoma suspects of African ancestry, higher risk of POAG conversion is independently associated with higher IOP, absence of hypertension, and presence of myopia. These findings can inform targeted screening and management strategies for this high-risk population. The unexpected association between absence of hypertension and increased conversion risk warrants further investigation into the complex relationship between systemic blood pressure and glaucoma pathogenesis in individuals of African ancestry.