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 microns) and thulium:YAG (2.0 microns) laser-induced scleral shrinkage for retinal 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 change of length between two reference points on the scleral surface, and quantified as a function of energy per pulse, total energy, scleral thickness, and intraocular pressure (IOP). Tissue effects were studied histopathologically.

RESULTS

Shrinkage was most dependent on total fluence and attained a maximum of 27% to 30% with an IOP of 4 mm Hg, regardless of scleral thickness or laser parameters, but decreased with increasing IOP. The thulium:YAG laser produced more efficient scleral shrinkage and less collagen damage than the holmium:YAG laser.

CONCLUSION

The recommended parameters for laser-induced scleral shrinkage are the thulium:YAG laser, with 2.4 J/cm2 per pulse and 12.0 to 14.4 J/cm2 total fluence (5 to 6 pulses). IOP control (< or = 4 mm Hg) is crucial during laser scleral buckling.