Multifocal Posterior Pigment Epitheliopathy in a Pachychoroid Eye Following Ahmed Glaucoma Valve Implantation: A Case Report.

We report a case of multifocal posterior pigment epitheliopathy (MPPE), a bullous variant within the pachychoroid disease spectrum, following Ahmed Glaucoma Valve (AGV) implantation in a patient with exfoliation glaucoma (XFG). An 81-year-old man with XFG underwent AGV implantation for uncontrolled intraocular pressure (IOP) of 48 mmHg despite maximal medical therapy. Preoperative best-corrected visual acuity (BCVA) was 20/20. Preoperative optical coherence tomography (OCT) demonstrated dilated pachyvessels in Haller's layer with attenuation of the inner choroid, consistent with an underlying pachychoroid phenotype, although the subfoveal choroidal thickness was unremarkable at 210 μm. Although postoperative IOP stabilized at 5-9 mmHg without early or hypotony-related structural complications, he developed multifocal pigment epithelial detachments (PEDs) and serous retinal detachment (SRD) in the macula one month postoperatively, accompanied by marked choroidal thickening (subfoveal choroidal thickness increasing from 210 to 362 μm) and pachyvessel dilatation. Fluorescein angiography (FA) revealed multifocal leakage in the superior and inferior nasal macula, and OCT angiography confirmed multiple PEDs overlying dilated choroidal vessels without macular neovascularization, leading to a diagnosis of MPPE. Following focal laser photocoagulation and recovery of IOP to 14 mmHg, the SRD resolved completely by postoperative day 93. However, the final BCVA was 20/320 due to persistent outer retinal changes. This case suggests that acute IOP reduction may have contributed to exudative decompensation by unmasking the latent exudative potential of a pre-existing pachychoroid substrate. Preoperative assessment of choroidal morphology and careful postoperative fundus monitoring should be considered in eyes with pachychoroid features undergoing glaucoma surgery.