True exfoliation syndrome is characterized by the peeling of a translucent membrane from the anterior lens capsule. The condition increases with age and despite the classic association with occupations involving intense heat, most cases are idiopathic. We have proposed a new clinical classification system dividing true exfoliation syndrome into 4 successive stages based on characteristic changes in the anterior capsule. We have also proposed a new mechanism related to iris movement and aqueous flow accounting for the capsular delamination. We have found that a detached flap occurs exclusively in areas that lack the anterior zonules. In our series of 259 consecutive patients, 47 (19.5%) patients developed primary open-angle glaucoma, 26 (10.0%) had primary angle-closure glaucoma, and 15 (5.8%) were primary angle-closure suspects. Twenty-six (10.0%) patients demonstrated spontaneous phacodonesis or anterior lens dislocation, of whom 14 also had secondary angle-closure and 2 had open-angle glaucoma. Histologic studies have shown that the lens dislocation is associated with a lack of anterior zonular support. All patients developed cataracts, predominantly nuclear sclerosis. The double-ring sign frequently occurs during capsulorhexis.