To examine the prevalence of macular telangiectasia type 2 and lesions characterizing it.

Population-based cohort study.

setting: City and township of Beaver Dam, 1988-1990. study population: A total of 4790 people 43-86 years of age. observation procedure(s): Grading from stereoscopic fundus photographs to measure macular telangiectasia type 2. main outcome measure: Prevalent macular telangiectasia type 2.

Macular telangiectasia type 2 was present at baseline in 0.1% of the population (95% confidence interval [CI] 0.09, 0.1). The frequencies of loss of retinal transparency, crystals in the inner retinal layers, blunted retinal vessels, localized intraretinal pigment migration in the juxtafoveolar region, and presence of yellow deposits and lamellar holes in the foveal area in those without macular telangiectasia type 2 varied from 0.06% for retinal telangiectatic vessels to 1.2% for lamellar holes. Smoking was associated with pigment clumping (odds ratio [OR] per pack year 1.02; 95% CI 1.00, 1.03; P = .02), retinal pigment epithelial (RPE) depigmentation (OR 1.02 per pack year; 95%CI 1.00, 1.04; P = .02), loss of transparency (OR 1.02 per pack year; 95% CI 1.00, 1.03; P = .008), and the presence of a yellow spot in the fovea (OR 2.24 current vs past or never smoker; 95% CI 1.29, 3.89; P = .004), but not with presence of macular telangiectasia type 2 (OR 2.72; 95% CI 0.45, 16.28; P = .27).

The prevalence of macular telangiectasia type 2 (0.1%) is higher than previously thought. These data are useful in estimating the burden of this condition in the population. The role of smoking in the development of macular telangiectasia type 2 requires further study.