Mixed-mechanism glaucoma associated with primary iris pigment epithelium cysts: a case report

Abstract Background We present a rare case of bilateral primary iris pigment epithelium (IPE) cysts associated with mixed-mechanism glaucoma and explore the potential role of mechanically mediated pigment dispersion in its pathogenesis. Case presentation A 60-year-old male presented with uncontrolled intraocular pressure (IOP) and progressive glaucomatous optic neuropathy in both eyes. Ultrasound biomicroscopy (UBM) revealed multiple IPE cysts with focal angle synechiae and direct contact between the cystic IPE and the lens–zonular complex. Dynamic gonioscopy demonstrated functionally open angles with Scheie pigment grade III-IV circumferential trabecular pigmentation, suggesting a pigment-related trabecular dysfunction as a major contributor to uncontrolled IOP. Phacoemulsification with intraocular lens implantation and Ahmed glaucoma valve (AGV) implantation were performed in both eyes. Intraoperatively, fragile cyst walls released pigment upon manipulation, suggesting the source of the pigment dispersion is the cysts. Postoperatively, IOP decreased but pigment deposition on the lens lasted for six months. Conclusions This case highlights a potential contribution of mechanically mediated pigment dispersion and trabecular dysfunction to IPE cyst-associated mixed-mechanism glaucoma, while an angle-closure component may also contribute to disease pathogenesis.