The origin of choroidal folds a clinical, histopathological, and experimental study.

Choroidal folds were defined as folds in Bruch's membrane and the anterior choroid. A clinical, histopathological and experimental investigation was performed.Eleven cases with choroidal folds were described. These cases included exophthalmos (from lymphoid hyperplasia, thyroid disease, orbital cellulitis, post-operative swelling, and orbital hemangioma), scleritis, retinal detachment due to metastatic lung carcinoma, hypotony, papilledema and choroidal detachment.The histology of 80 unselected enucleated eyes was examined and choroidal folds were found in 23 (29%). The most common cause was choroidal thickening due to vascular engorgement, hemorrhage or inflammation. Folds were also formed by tissue compression at the edge of a choroidal tumor or scleral implant, or by scleral thickening.Choroidal folds were produced in vivo in cat's eyes by traction on the optic nerve or by hypotony after paracentesis. The irregular folds after hypotony could be oriented by traction on the optic nerve.It was hypothesized that choroidal folds are produced by any mechanism which forces Bruch's membrane to fold, and that traction on the optic nerve may play a role in the characteristic horizontal temporal orientation of choroidal folds seen in many patients.