Unusual anterior and posterior segment features of coats disease

To report the clinical course and management of unusual anterior and posterior segment features of Coats disease and their relation to the age of the patients to increase the awareness towards these rare clinical features rarely described in the current literature.A retrospective descriptive review of 45 eyes of 45 patients affected by Coats disease was conducted at the Retinoblastoma Referral Center and Ophthalmology Unit of the University of Siena in Italy analyzing data from 2000 to 2022. Medical records and images were revised to find some cases presenting unusual anterior and posterior segment features in patients affected by Coats disease.We identified therefore 4 unusual clinical conditions: retinal macrocysts, anterior chamber cholesterolosis, fovea-sparing Coats disease and secondary vasoproliferative tumor.Two patients presented with retinal macrocyst (2/45 = 4.4%), one with anterior chamber cholesterolosis (1/45 = 2.2%), two with fovea sparing Coats disease (2/45 = 4.4%) and one with vasoproliferative tumor associated (1/45 = 2.2%) for a total of six (6/45 = 13.3%) patients manifesting unusual anterior or posterior segment features in Coats disease.Unusual anterior and posterior segment features of Coats disease such as retinal macrocyst and anterior chamber cholesterolosis have been more frequently reported in younger children while fovea-sparing and vasoproliferative tumors have been more commonly described in older patients. Age is then a strong prognostic marker which allows to distinguish two different phenotypes of Coats disease: patients younger and older than 3 years old with more aggressive and milder phenotype respectively.