Purpose: To evaluate the middle term tonometric results of a new filtering procedure, the non penetrating deep sclerectomy with collagen device, in primary open-angle glaucoma. This technique aims to eliminate or minimize the complications of classical trabeculectomy.
Material and method: This procedure has been developed by Koslov et al. Under a limbal-base conjunctival flap and a superficial scleral flap, the ablation of a deep scleral flap takes away the external wall of Schlemm's canal, leaving only the Descemet membrane. A visible filtration across the opened Schlemm's canal and Descemet membrane is obtained. To improve the aqueous filtration, a cylindric collagen device, made from biocompatible porcine scleral tissue, known for its high water content, is fixed in the deep scleral bed with a 10/0 nylon suture. This device provides a support for the elimination route of aqueous humor and acts like a sponge, carrying the liquid by capillary action. It is sterilized by irradiation. Full guarantee against viral contamination is provided. This procedure ends in one suture (40/0 nylon) of superficial scleral flap and conjunctival closing suture. We conducted a retrospective study. Our material included 159 patients (92 males, 65 females), 2/9 eyes. The mean age was 65 years (11-91). The mean follow-up : 8 months (3-20). The types of glaucoma were: POAG: 183 eyes; juvenile POAG: 18 eyes: pigmentary glaucoma: 11 eyes; capsular glaucoma: 7 eyes, 58 eyes (40 patients) presented one or several risk factors of failure for filtering surgery.
Results: The mean pre-operative IOP was 24 mmHg +/- 6.60; 15.7 +/- 5.30 at the end of the follow-up (delta average IOP: 9.1 +/- 7.1). The probability success rate (IOP < or = 20 mmHg), according to the Kaplan-Meier Method, was 89% at six months, 75.6% at 16 months. With monotherapy with beta blockers, 79% at 16 months. It was better in the without risk factors group. The mean change in visual acuity was inferior to 0.1 at the end of the follow-up. Except several hyphemas, no complications of the trabeculectomy were observed. The reelevation of IOP was due to an internal obstruction (goniosynechiae or bad filtration), it was treated with Nd-Yag laser with a 2/3 of success rate. External obstruction was treated by 5FU injections into the bleb.
Conclusion: Non penetrating deep sclerectomy with collagen device can be an excellent alternative to trabeculectomy in open and wide angles. It does not modify visual actuity. It carries less complications than trabeculectomy and the use of antimitotic agents is safer.