Quantification of holmium: YAG and thulium: YAG laser-induced scleral shrinkage for buckling procedures.
OBJECTIVE
To quantify and compare holmium:YAG (2.1 microns) and thulium:YAG (2.0 microns) laser-induced scleral shrinkage for retinal buckling procedures.


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.


CONCLUSIONS
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.
Sasoh
M
M
Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, FL 33136, USA.
Parel
J M
JM
Manns
F
F
Nose
I
I
Comander
J
J
Smiddy
W E
WE
D006801:Humans; D066298:In Vitro Techniques; D007429:Intraocular Pressure; D053685:Laser Therapy; D015203:Reproducibility of Results; D012590:Sclera / Q000473:pathology* / Q000601:surgery; D012591:Scleral Buckling / Q000379:methods*