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Traci E. Clemons, Tunde Peto, Ferenc Sllo, Emily Y. Chew, Mark C. Gillies, Alan C. Bird, MacTel Research Group; Estimated rates of progression of MacTel Type 2 Characteristics: Results from the MacTel Study. Invest. Ophthalmol. Vis. Sci. 2012;53(14):982.
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To provide estimated rates of progression of visual acuity loss and various characteristics of idiopathic macular telangiectasis (MacTel) Type 2.
MacTel Type 2 affects both eyes and is characterized by retinal opacification, vascular telangiectasis, right-angle venules, intraretinal crystalline deposits, foveal thinning, retinal pigment epithelial hypertrophy, and, in some cases, intra-/sub-retinal neovascularization. Little is known regarding the pathogenesis and natural history of patients with MacTel Type 2. To this end the Natural History Study of Macular Telangiectasia (MacTel Study) was started in 2005. Annual exams included best-corrected visual acuity and multi-modal imaging of the fundus, including spectral domain optical coherence tomography (OCT). Mixed effects and repeated measures logistic regression models were used to compute means (continuous) and probabilities (categorical) of progression over time. This is the first report of progression rates of vision loss and other characteristics of MacTel Type 2.
Between November 2005 and November 2011 a total of 657 participants were enrolled through 26 clinical centers representing 8 countries (Australia, France, Germany, India, Israel, Switzerland, United States and United Kingdom). Of these participants, 398 had at least one year of follow-up (median follow-up = 3 years). 60% of the 398 participants were male and 28% reported a history of diabetes. The average age for the follow-up cohort was 60.5 ± 9 years. Baseline visual acuity was 73.0 (Snellen equivalent ~ 20/40) ± 11.9 letters and 50% had the presence of an IS/OS PR break as measured by OCT. The annual rate of change in visual acuity was approximately 1 letter loss (-0.94 ± 0.08 letters). There was no difference by in the rate of change by history of diabetes or presence of IS/OS PR break at baseline. The probability of progression from absence to presence of an IS/OS PR break was 13% after 1 year; 38% after 3 years; and 72% after 5 years.
Event rates observed in this large natural history study may be useful in understanding the progression of the disease and computing expected event rates for future studies of therapies targeted at reducing the risk of progression of MacTel Type 2.
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