We studied the pattern of break formation in 60 eyes with myopic lacquer cracks, angioid streaks, or traumatic tears in Bruch's membrane, using a graphics composition technique and computer analysis of digitized images. Lacquer cracks were found in a reticular distribution within a posterior staphyloma; angioid streaks occurred in a spider-web configuration centered on the optic nerve; traumatic tears were characteristically curved, perineural, and eccentric temporally. The specific break patterns imply the operation of biomechanical forces.