Trabeculectomy trapdoor separation with allergic periorbital dermatitis: an unusual late-onset complication of guarded filtration surgery.

Hypotony post trabeculectomy may be the result of excessive aqueous outflow. Herein a case of an elderly man with excessive filtration 2 years post trabeculectomy resulting from trapdoor separation associated with allergic periorbital dermatitis is presented. Quaternary ammonium compounds are a significant cause of allergic periorbital dermatitis. Chronic rubbing associated with allergies to multiple topical quaternary ammonium compound-containing ophthalmic preparations is likely to have contributed to the trapdoor autotrauma and separation in this man with a background of allergic contact dermatitis.