- The designated primary study eye must have at least one well-demarcated area of atrophy as imaged by fundus autofluorescence with a minimum diameter of 300 microns and all lesions together must add to less than or equal to 12 mm2 (equivalent to no more than 5 disc areas in a least one eye) and a BCVA of 20 ETDRS letters (20/400 Snellen equivalent) or better.