Abstract
Pilot studies for laser scleral buckling made it clear that quantification of scleral shrinkage was required for precision and reproducibility of the treatment. For the quantification either the Ho:YAG (2.10 micrometers ) or the Tm:YAG (2.01 micrometers ) lasers were applied to the equatorial sclera of human cadaver eyes. Two slightly overlapping spots (2.8 mm (phi) ) were applied. Shrinkage rate was expressed as: [(Scleral length before treatment--Schleral length after treatment)/Schleral length before treatment] X 100(%). Shrinkage rate was measured changing several parameters. Total fluence, energy/pulse, scleral thickness, tissue temperature, age, and intraocular pressure. Shrinkage rate was found to be mainly function of total fluence attaining a maximum of 26 - 30% in adult and 46% in infant eyes at a 3 - 4 mm Hg intraocular pressure. Rising tissue temperature from room temperature to physiologic levels reduced the laser energy requirements but not the maximum shrinkage level. From the same shrinkage effect in the practical range of total fluence, less energy (56 - 60%) was required with the Tm:YAG laser. The data acquired in this study will help us construct an algorithm to predict the outcome of laser scleral buckling in patients.
