The Prevalence of Type 2 Idiopathic Macular Telangiectasia in Two African Populations

Abstract

Purpose: Type 2 idiopathic macular telangiectasia (MacTel) is a progressive retinal disease associated with a slow deterioration of visual acuity, starting in the fifth to seventh decades of life. The etiology and pathogenesis of the disease are little known, and no effective therapy is available. We aimed to estimate the prevalence and describe the phenotype of type 2 MacTel in two African populations.

Methods: From two population-based cross-sectional surveys conducted nationally in Nigeria and in the Nakuru district of Kenya, patients with fundus features of type 2 MacTel were selected. Diagnosis was based on color fundus images, grading performed according to the MacTel Study protocol and staged using the Gass and Blodi system. Disease phenotype and clinical characteristics of affected participants were assessed.

Results: Of 8599 total participants, five showed a phenotype compatible with type 2 MacTel. Prevalence was estimated as 0.06% (95% confidence interval [CI] 0.02–0.21%) in Kenya, 0.06% (95% CI 0.01–0.17%) in Nigeria, and overall at 0.06% (95% CI 0.02–0.14%). Mean age was 62 years (SD 5 years), four of five affected participants were female, and none had a history of diabetes. Median corrected visual acuity was 6/12 in the better eye and 6/69 in the worse eye.

Conclusions: The estimated prevalence and phenotype of type 2 MacTel in the African populations examined were similar to those in predominantly white populations. All data published so far are based on the analysis of color fundus images only and are thus likely to underestimate the true prevalence of this disease.

KEYWORDS::

• Macular telangiectasia
• Prevalence
• Phenotype
• Retina
• Imaging

ACKNOWLEDGMENTS

Financial Support: The authors wish to thank Sightsavers, the Velux Stiftung and CBM for funding of the Nigeria Blindness and Visual Impairment Survey, the British Council for Prevention of Blindness and the Fred Hollows Foundation for financial support of the Nakuru District Blindness Survey, the NIHR BMRC for Ophthalmology and the Lowy Medical Foundation for funding of the MacTel project.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the article.