Photoablative Laser-Grid Trabeculectomy in Glaucoma Filtering Surgery: Histology and Outflow Facility Measurements in Porcine Cadaver Eyes
2000; Volume: 31; Issue: 1 Linguagem: Inglês
10.3928/1542-8877-20000101-10
ISSN2325-8179
AutoresP. C. Jacobi, T. S. Dietlein, T Colling, G. K. Krieglstein,
Tópico(s)Ophthalmology and Eye Disorders
Resumo* BACKGROUND AND OBJECTIVE: Midinfrared laser technology opens new perspectives in experimental glaucoma surgery. The aim of the study was to determine the efficacy of grid-laser trabeculectomy to reduce aqueous outflow resistance sufficiently in perfused porcine cadaver eyes. * MATERIALS AND METHODS: Twenty-five freshly enucleated porcine cadaver eyes were randomly assigned to either laser-grid trabeculectomy (LGT), conventional trabeculectomy (CT), or control. In all surgical cases a scierai flap was prepared in a standardized manner. In order to penetrate into the anterior chamber a 1 × 2 mm sclerectomy was performed in CT, and 10 transscleral ablation craters were created in LGT. An erbium:YAG laser (2.96 µm) was used for transscleral photoablation. Radiation was delivered in a single 6 mJ-pulse of 200 µs duration by means of an articulated zirconium fluoride optical fiber and a 200 µm quartz fiber-tip. Outflow facility was measured at a constant perfusion pressure. * RESULTS: Laser-grid trabeculectomy (LGT) yielded reproducible ablation areas varying between 210-300 µm in diameter, with 90% being full-thickness penetrations. Collateral thermal damage was less than 30 µm. Outflow facility measurements revealed a statistically significant increase (mean ± SD) from 0.255 ± 0.096 µL/min/mm Hg in control eyes (n = 9) to 0.772 ± 0.157 µL/min/mm Hg in the LGT group (n = 9), and 2.957 ± 0.602 µL/min/mm in the CT group (n = 7). Flattening of the anterior chamber, folding of Descemets membrane, and iris prolapse were only observed in the CT eyes but not in the GLT group. * CONCLUSION: Application of the laser-grid trabeculectomy produces patent transscleral perforation with minimal collateral tissue damage and effects a significant reduction (67%) in outflow resistance without any postoperative hypotony-related complications. [Ophthalmic Surg Lasers 2000;31:49-54.]
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