Probe placement and energy levels in continuous wave neodymium-YAG contact transscleral cyclophotocoagulation.

To improve the reliability of the technique, contact transscleral cyclophotocoagulation was performed using a continuous wave neodymium-YAG laser. Radiation was delivered via a fiberoptic system to two human eyes destined for enucleation due to choroidal melanoma. Distances from the corneal limbus to where the fiberoptic probe was placed, perpendicular to the conjunctiva, were varied, as were the energy values. Gross, light microscopic, and scanning electron microscopic examinations revealed that contact probe placement at a distance of 1.5 mm from the corneal limbus with an energy setting of 2 J provided optimum cyclophodestructive results. Slight superficial damage to the sclera was detected, but observations indicated no alterations to the adjacent anatomical structures. To obtain lesions to the ciliary processes in living eyes similar to those previously noted in human cadavers, comparatively lower energy values (2 J) were required. To exploit all the mechanisms that may lead to a decrease in intraocular pressure, precise hitting of the aqueous humor secretory structure may prove to be of primary importance.