title: The prevalence of type 2 idiopathic macular telangiectasia in two African populations.
abstract: OBJECTIVE
  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.
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK. Ferenc.Sallo@moorfields.nhs.uk
authors.forename: Ferenc B
authors.initials: FB
authors.lastname: Sallo
authors.forename: Irene
authors.initials: I
authors.lastname: Leung
authors.forename: Wanjiku
authors.initials: W
authors.lastname: Mathenge
authors.forename: Fatima
authors.initials: F
authors.lastname: Kyari
authors.forename: Hannah
authors.initials: H
authors.lastname: Kuper
authors.forename: Clare E
authors.initials: CE
authors.lastname: Gilbert
authors.forename: Alan C
authors.initials: AC
authors.lastname: Bird
authors.forename: Tunde
authors.initials: T
authors.lastname: Peto
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D007630:Kenya / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009549:Nigeria / Q000453:epidemiology; D010641:Phenotype; D015995:Prevalence; D058456:Retinal Telangiectasis / Q000145:classification / Q000453:epidemiology*; D014792:Visual Acuity / Q000502:physiology