Background  

This study evaluated the use of a CO₂ laser for performing deep sclerectomy in nonpenetrating filtration surgery.

Methods  

Three experimental models were performed: enucleated sheep and cow eyes (n=18) to determine optimal irradiation parameters, live rabbit eyes (n=20) to test feasibility, and cadaver eyes (40 procedures in 20 eyes) to study effects in human eyes tissue. After a half-thickness scleral flap was created, deep sclerectomy was performed by CO₂ laser applications on the scleral bed down to the trabeculo-Descemet’s membrane.

Results  

Fluid percolation was repeatedly achieved without penetration in sheep and cow eyes using scanned laser energy of 5–10 W at a pulse duration of 200 μs and a working distance of 35 cm. In live rabbits, deep sclerectomy was achieved without perforation in 19/20 eyes. Intraocular pressure was significantly decreased on the first postoperative day (10.3±5.1 mmHg lower, on average, than in the nonoperated fellow eye; P<0.001), and this persisted for 21 days. Operations on all cadaver eyes resulted in effective fluid percolation. Penetration of the scleral wall occurred in five cases only after repeated laser applications with high energy. Histologically, a thin sclerocorneal intact wall was demonstrated at the sclerectomy bed. Collateral tissue damage did not extend beyond 100 μm, and adjacent structures remained unharmed.

Conclusions  

CO₂ laser-assisted deep sclerectomy is a feasible and apparently safe procedure.