Secondary subconjunctival implantation of a biodegradable collagen-glycosaminoglycan matrix to treat ocular hypotony following trabeculectomy with mitomycin C

Abstract

Aim: Biodegradable collagen glycosaminoglycan matrices (CGM) have been introduced to glaucoma filtration surgery in order to prevent scarring of the filtering bleb. In this retrospective case series, we describe a new surgical concept for treating symptomatic ocular hypotony following filtration surgery with mitomycin C by a secondary subconjunctival implantation of a CGM. Methods: Depending on bleb morphology, a CGM implant with a diameter of 6 or 12 mm was placed subconjunctivally on the scleral flap in 12 eyes displaying symptomatic ocular hypotony with (n=2) or without (n=10) bleb leakage. Median period between trabeculectomy and this intervention was 4.5 months (range, 1-72 months). Results: Mean intraocular pressure significantly increased from 4.4±1.4 mm Hg to 9.9±2.8 mm Hg (p<0.0001) over a median follow-up of 6 months (range, 2-18 months). Mean visual acuity improved significantly (p=0.0012). Postoperative complications included implant re-exposure in one eye and persistent choroidal detachment requiring resurgery in another eye. Conclusions: Subconjunctival implantation of CGM may present an additional surgical tool in the treatment of symptomatic ocular hypotony after filtering surgery. The mechanism of action may be counter-pressure to the scleral flap and secondary wound healing around the CGM scaffold. Long-term observations are needed to fully evaluate this new surgical concept.