The effects of a neodymium: YAG laser, working in the free-running mode (1 and 20 millisecond pulses), upon the ciliary body via the transscleral route have been studied using 16 autopsy eyes. The experiments described were designed to find an efficient strategy of transscleral cyclodestruction of the ciliary body. It was found that pulse energies of between 6 and 7 Joules, an exposure duration of 20 milliseconds, and maximal defocusing are optimal. A beam, tangentially oriented and positioned 1/2 to 1 mm posterior to the limbus has a high probability of hitting the ciliary body and damaging the ciliary processes. In these experiments a first generation of contact lenses could not be demonstrated to have an advantageous effect.