We compared the contact cyclodestructive effects (both gross and histologic) achieved with diode and Nd:YAG laser wavelengths (810 and 1064 nm, respectively), using equivalent energy doses, released by means of a new optical delivery system in a human eye that was soon to be enucleated because of a choroidal melanoma. For both lasers, a fiber optic system (400 microns) with a focusing microlens placed at the end of the fiber was used. The center of the beam was placed 1.5 mm from the corneoscleral limbus. At medium (5.2 to 6.6 J) and higher (7.8 J) energy levels, the cyclodestructive thermal damage produced by the diode laser appeared more widespread than that created by the Nd:YAG laser. At lower levels (3.6 to 3.9 J), both laser treatments produced similar lesions. The new delivery system proved to be safe and effective in achieving the desired cyclodestructive effects at both wavelengths.