Effect of a Fenestration Between an Intrascleral Lake and Supraciliary Space on Deep Sclerectomy

To evaluate the effects of a scleral fenestration on the surgical outcomes of modified deep sclerectomy (DS).

We retrospectively studied the surgical outcomes of 83 eyes of 83 patients after modified DS for primary open-angle glaucoma (POAG) or ocular hypertension. In 39 eyes, combination of DS, incision of the trabeculo-Descemet's membrane, and iridectomy were performed (DSF-); in 44 eyes, a scleral fenestration between the supraciliary space and lake was added to the DSF- (DSF+). Forty-eight eyes of 48 patients with POAG who underwent trabeculectomy with adjunctive mitomycin C (lect MMC) served as controls.

The probability of bleb survival was more common in the following order: lect MMC>DSF->DSF+ (P=0.0029). A significantly greater intraocular pressure (IOP) reduction occurred in the lect MMC group compared with the DSF+ (P=0.0015) and DSF- (P=0.0006) groups. So far as the eyes that underwent DS were concerned, bleb formation (P=0.0130) and a scleral bed fenestration (P=0.0315) significantly lowered the IOP by the Cox proportional hazard model. In eyes treated with DSF+, the positive IOP-lowering effect of the fenestration was counterbalanced by inhibited bleb formation and resulted in equivalent IOP reductions in the DSF+ and DSF- groups (P=0.9881). IOP reduction by DSF+ without a bleb was 25.0% at 1 year (P=0.00015) and this reduction increased to 43.2% (P=0.0001) when eyes accompany a bleb and scleral fenestration.

Both the scleral fenestration and bleb formation lower IOP, whereas the scleral fenestration suppresses bleb formation in patients treated with DS.