Abstract

P 007

Clinicopathologic findings of early Ahmed Glaucoma Valve encapsulation in juvenile glaucoma patients

Thieme H.¹, Hofmann-Rummelt C.², Schulze A.¹, Pfeiffer N.¹, Kottler U. B.¹
Department of Ophthalmology, ¹Johannes Gutenberg-University, Mainz, ²Friedrich-Alexander-University Erlangen-Nurnberg, Erlangen

Objective: The main reason for early Ahmed Glaucoma Valve (AGV) insufficiency with consecutive elevation of intraocular pressure (IOP) in adult glaucoma patients is the occlusion of the valve tube and base plate. We report on three eyes of three teenagers (aged 12 to 19 years) who required operative intervention due to early (2 to 6 months after implantation) AGV encapsulation.
Methods: Intraoperative imaging and postoperative histopathologic examination of tissue covering the AGV.
Results: Intraoperatively, no ingrowth of tissue into the valve chamber was noted, AGV removal was not necessary. Resection of the capsule led to an immediate flow through the valve mechanism and to a drop in IOP. Histopathologically, the tissue consists of layers of dense fibrous tissue with marked elastic degeneration. The macroscopically visible bisection corresponds with the highly vascularised superficial layer with minor cellularity and the slightly vascularised deep layer with dense cellularity, directly overlying the AGV implant. The juvenile Tenon’s capsule shows fibrotic activity with myofibroblastic transformation in the deeper layer. At the direct transition zone towards the implant, a pseudoendothelium is formed. There are focal granulomatous inflammatory reactions surrounding suture material, but general inflammatory infiltration is scarce.
Conclusions: Early AGV failure in juvenile glaucoma patients can be caused by an extensive conjunctival scarring response with consecutive AGV encapsulation. Revision of scar tissue prevented the necessity of valve explantation in our patients so far.

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