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

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 12mm 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 4.5months (range, 1-72months). Results Mean intraocular pressure significantly increased from 4.4 +/- 1.4mmHg to 9.9 +/- 2.8mmHg (p<0.0001) over a median follow-up of 6months (range, 2-18months). 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.