Background: Choroidal neovascularization (CNV) is a common cause of legal blindness in developed countries. In patients younger than 50 years of age, CNV can be due to various causes, but to the authors' knowledge there has been no large epidemiologic study to compare the relative incidence of the various causes of CNV in this younger-aged group. Methods: A retrospective study was performed of patients seen over a 30-month period to precisely define the relative incidence of the various etiologies of CNV in patients younger than 50 years of age who had been referred to a tertiary care ophthalmology department in western Europe. Results: Clinical charts and angiograms of 363 patients were reviewed. The etiology of CNV was high myopia in 225 (62%) patients, pseudo-presumed ocular histoplasmosis syndrome in 42 (12%), angioid streaks in 17 (5%), and miscellaneous hereditary, or traumatic or inflammatory disorders in 16 (4%). Choroidal neovascularization could not be related to any etiology in 63 (17%) patients, and was considered to be idiopathic lesions. Choroidal neovascularization was subfoveal in 62% of the patients due to myopia versus 30% to 36% in patients due to other etiologies. Laser photocoagulation was applied in the majority of patients due to all etiologies except myopia. Conclusion: These data provide the relative incidence of the various etiologies of CNV in young patients and emphasize the importance of myopia as an etiology of CNV in such patients. In addition, an apparent preferential localization of CNV to the subfoveal region in myopic eyes precludes its treatment with photocoagulation.
