Diode-pumped solid-state lasers in ophthalmology

Visible lasers operating in the green and yellow regions of the spectrum have long been employed for ophthalmic medicine. Tissue response to various wavelengths enables new treatment modalities: visible radiation passes through the cornea for conventional retinal treatment; IR radiation can avoid the cornea and pass through the more robust sclara (white of the eye), and near IR radiation exhibits some absorption allowing tran-sclaral treatment with heating of the trabecular meshwork, or pigmented regions of the retina. The requirement for true CW laser output has made the creation of an effective solid-state replacement of the ion laser quite difficult. While obtaining CW yellow output remains fairly elusive, next generation intracavity doubled diode-pumped solid state lasers producing CW green outputs are now in the medical market. Recent advances in nonlinear materials have brought about new nonlinear media. While diode-pumped laser sources have advanced for CW green and yellow generation, pump diodes themselves have also improved in beam quality and wavelength agility. In addition to wavelength agility of the treatment source, pulse format also appears to be a significant variable in patient response to treatment. We discuss the application of these lasers in ophthalmic medicine for diabetic retinopathy, retinopathy of prematurity, glaucoma, and treatment of ocular tumors through photodynamic therapy and thermal coagulation.