Abstract
Purpose :
Primary open-angle glaucoma (POAG) has been reported to occur more frequently in Africans, and to follow a more severe course. We aimed to describe the various clinical characteristics of POAG in a large cohort of patients from Tanzania and South Africa.
Methods :
Patients were ascertained from the glaucoma clinics of an university hospital in Cape Town, South Africa; and from an university hospital and 2 large referral hospitals in Tanzania. We included 911 patients (>35 years) and 711 controls (>55 years), of whom 58% was male and 42% female. All participants underwent an extensive ophthalmic examination including visual acuity (VA), intra ocular pressure (IOP), gonioscopy, central corneal thickness (CCT) measurement, fundus examination and photography, and visual field testing/OCT when available. All participants filled out a questionnaire concerning family history, ethnic background, and ophthalmic and general medical history. Patients were diagnosed according to the ISGEO-criteria for POAG.
Results :
Participants originated from 105 different tribes in Tanzania and from 7 tribes in South Africa, of which Chaga predominated in Tanzania (61%), and Xhosa in South Africa (72%). A positive family history for POAG was recorded in 29% of patients. Age at diagnosis was 62 (sd 11) years, and 60% of patients presented with blindness (VA ≤0,10) in at least one eye at diagnosis. Mean IOP was 37 (sd 11) mmHg, mean CCT was 503 (sd 3) µm, the angle of the anterior chamber was ≥3 according to Shaffer in all patients, and mean vertical cup-disc ratio (VCDR) was 0,85 (sd 0,1). Patients using IOP-lowering medication achieved an average IOP reduction of 14 (sd 6) mmHg, while those undergoing glaucoma surgery reduced with 20 (sd 5) mmHg (P=0,005). The self-reported compliance of IOP-lowering medication was 40%.
Conclusions :
In populations of African ethnicity, POAG indeed appears to be a significant eye disorder. Patients were diagnosed in a late stage of disease at a relatively young age. Presenting IOP was much higher than described in other ethnicities, while CCT was considerably lower. The low compliance to therapy favors IOP-lowering surgery as the first choice of treatment. Deciphering the reasons for the more severe phenotype in Africans will be the next step in understanding the pathogenesis of POAG.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.