Erbium-YAG laser-assisted preparation of deep sclerectomy

• Published in: Graefe's archive for clinical and experimental ophthalmology 2000-09, Vol.238 (9), p.792-796
• Main Authors: KLINK, Thomas, LIEB, Wolfgang, GREHN, Franz
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Descemet Membrane - cytology; Descemet Membrane - surgery; Equipment Design; Fiber Optic Technology; Glaucoma - surgery; In Vitro Techniques; Intraocular Pressure - physiology; Laser Therapy - instrumentation; Medical sciences; Minimally Invasive Surgical Procedures - methods; Ophthalmology; Prognosis; Sclera - surgery; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the eye and orbit; Swine; Trabecular Meshwork - cytology; Trabecular Meshwork - surgery; Trabeculectomy - methods
• ISSN: 0721-832X; 1435-702X
• DOI: 10.1007/s004170000169

Deep sclerectomy and viscocanalostomy are becoming more and more popular as non-penetrating filtering procedures. The purpose of the present study was to simplify the technique of this procedure and to reduce the rate of unintended perforations during the preparation of the deep lamella. 20 enucleated porcine eyes were used. A superficial lamellar scleral flap with an area of 5x5 mm as for trabeculectomy was surgically prepared. Using a pulsed erbium:YAG laser the deep lamella (220 +/- 40 microm) with an area of 4x3 mm was removed. Ablation was performed with an energy of 40-100 mJ, a frequency of 1-10 Hz and a spot size of 500 microm and 1 mm (divergent beam). During the procedure the intraocular pressure was kept constant by continuous infusion. Finally the eyes were analyzed histologically. After initial trials it was possible to ablate the remaining deep corneoscleral lamella with the erbium:YAG laser without perforating into the anterior chamber. Starting with an energy of 70-85 mJ and a reduction to 40-60 mJ when reaching deeper layers, a spot size of 500 microm and a 10 Hz repetition rate gave the highest safety and efficiency in preparation. After a learning curve it was possible to preserve Descemet's membrane and intact trabecular meshwork in 10 consecutive operations as demonstrated by histology. Erbium:YAG laser-assisted deep sclerectomy offers an alternative to microsurgical preparation of the deep scleral lamella. The thermal damage is minimal (10-40 microm) and scarring may therefore not be stimulated.