Iridoschisis is a rare condition of uncertain etiology characterized by a cleavage of the iris layers. We report four cases studied by fluorescein angiography to display possible occurrence of vascular abnormalities in the pathogenesis of the disease. Case 1: 80 year old woman with bilateral schisis of the peripheral iris, in the inferonasal quadrant in RE and inferotemporal in LE. A shallow anterior chamber was present in OU; IOP was 18 in RE and 15 in LE. No corneal abnormalities were present. Fluoroiridography showed a normal pattern filling of the iris vascularity, that was more visible in the schisis area. Case 2: 66 year old man with diabetes and open-angle glaucoma operated on for trabeculectomy five years previously. The examination showed a normal cornea, a shallow anterior chamber and miotic pupils for pilocarpine therapy. IOP was 12 in OU. The iridoschisis was present in RE in the lower sectors which were totally involved from the outer iris to the inner pupillary margin. Fluoroiridography indicated a normal vessel perfusion without any abnormality in the affected sectors. A slight bilateral pupillary dye leakage without any stromal diffusion was attributable to the patient's age. Case 3: 55 year old woman treated with miotics in RE for a glaucoma diagnosed after head trauma twenty years before, after which the vision in LE was reduced to 2/200 for post-traumatic optic nerve atrophy. No corneal abnormality was present. The anterior chamber was shallow and the ocular tension was 14 in RE and 10 in LE.(ABSTRACT TRUNCATED AT 250 WORDS)