Two patients who had lost central vision in one eye due to a histoplasmic disciform macular scar received prophylactic argon laser photocoagulation to one or more atrophic lesions (histo spots) in the second macula in an effort to reduce the risk of developing active neovascularization in the second eye. Despite this prophylactic treatment, both patients developed a choroidal neovascular membrane from the photocoagulation scar.