Optical properties of conjunctiva, sclera, and the ciliary body and their consequences for transscleral cyclophotocoagulation.

A number of recent studies have demonstrated the success of Nd:YAG and diode laser transscleral cyclophotocoagulation in the treatment of advanced glaucoma. Wavelength selection, however, has seldom been based on a clear understanding of the optical properties of tissues involved. The optical properties of conjunctiva, sclera, and the ciliary body adjacent to the limbus were investigated to find an optimal wavelength range for transscleral cyclophotocoagulation. The absorption and scattering coefficients of these layers were determined in the 300-1200-nm wavelength range by the use of a one-dimensional inverse adding-doubling method. The measured optical properties of conjunctiva, sclera, and the ciliary body provide a basis for a comparative analysis of the laser wavelengths used clinically for transscleral cyclophotocoagulation.