The Macular Photocoagulation Study (MPS) guidelines for interpreting angiograms of eyes with subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration and for treating these lesions are described to assist ophthalmologists in applying the results of the MPS clinical trials of laser treatment. The MPS criteria for treatment of subfoveal neovascular lesions require the following conditions: (1) the presence of classic CNV, (2) well-demarcated lesion boundaries, and (3) size less than or equal to 3.5 disc areas (if no previous treatment of CNV in the macula was performed). In subfoveal recurrent CNV, size had to be such that after treatment of the recurrence, the final treatment scar (prior treatment scar and newly treated area) would be no larger than 6 disc areas and would spare some retina within 1500 microns of the center of the foveal avascular zone. Treatment of all classic and occult CNV and areas in which the boundaries of CNV may be obscured is recommended, as it treatment extending at least 100 microns beyond the peripheral boundaries of the lesion. In subfoveal recurrent CNV, treatment should also extend at least 300 microns into the previous treatment scar and cover any feeder vessels. The desired end point for the intensity of the laser burns is a uniformly white lesion.