Solitary Free-floating Iris Cyst Associated with Bilateral Pigment Dispersion Syndrome. Report of a Case

Case Report: A 27-year-old white man with a 5-year history of pigment dispersion syndrome (PDS) presented for evaluation. His past ocular history was significant for bilateral intraocular pressure (IOP) elevation that had required IOP-lowering medication (beta-blocker-prostaglandin analogue fixed combination). On ophthalmic examination, the visual acuity was 20/20 without correction in both eyes. Anterior chamber slit-lamp examination revealed a pigmented round mass with modest transillumination at six o'clock position of the right eye. When asked, the patient reported that he had first noticed a shadow in his right eye during childhood when he was flexing his neck and keeping a face-down position for a few seconds. During a head-flexing test, the mass freely floated in the AC. When the patient extended the neck, the round mass could be seen in front of the pupil. After a few moments, the mass would slowly fall to the iridocorneal angle at the six o'clock position. Ultrasound biomicroscopy and anterior-segment optical coherence tomography confirmed that the lesion was a pigmented cyst without internal reflectivity. Specular microscopy examinations, performed to exclude cyst-induced corneal endothelium compromise, revealed a cell-density of approximately 3000 cells/mm² in both eyes. Gonioscopy showed an open angle with trabecular pigmentation and funduscopy a cup-to-disc ratio of 0.5 bilaterally. Visual fields and OCT tests were within normal limits. Conclusions: The etiology of free-floating iris cysts is unclear, but it is generally agreed that these masses are usually dislodged pigment epithelial cysts. This is the first report of a unilateral free-floating iris cyst associated with bilateral PDS.