Schematic comparison of the margin of pediatric (left) and adult (right) colobomas. 1 = intercalary membrane, 2 = glial triangle, 3 = point of reversal, 4 = duplication, 5 = locus minoris resistentiae, 6 = pigmented epithelium, 7 = extracolobomatous retina. Young colobomas are characterized by features 1 through 7, adult by 1, 6, and 7. The absence of 2 through 5 possibly results in a more resilient barrier.