QUANTIFICATION OF HOLMIUM-YAG AND THULIUM-YAG LASER-INDUCED SCLERAL SHRINKAGE FOR BUCKLING PROCEDURES

BACKGROUND AND OBJECTIVE: To quantify and compare holmium:YAG (2.1 mu m) and thulium:YAG (2.0 mu m) laser-induced scleral shrinkage for reti nal buckling procedures. MATERIALS AND METHODS: Two overlapping spots of either laser radiation were applied at the equatorial sclera of 50 human cadaver eyes. Scleral shrinkage was expressed as a relative chan ge of length between two reference points on the scleral surface, and quantified as a function of energy per pulse, total energy, scleral th ickness, and intraocular pressure (IOP). Tissue effects were studied h istopathologically. RESULTS: Shrinkage was most dependent on total flu ence and attained a maximum of 27% to 30% with an IOP of 4 mm Hg, rega rdless of scleral thickness or laser parameters, but decreased with in creasing IOP, The thulium:YAG laser produced more efficient scleral sh rinkage and less collagen damage than the holmium:YAG laser. CONCLUSIO N: The recommended parameters for laser-induced scleral shrinkage are the thulium:YAG laser, with 2.4 J/cm(2) per pulse and 12.0 to 14.4 J/c m(2) total fluence (5 to 6 pulses). IOP control (less than or equal to 4 mm Hg) is crucial during laser scleral buckling.