Transpupillary Thermotherapy for Age-Related Macular Degeneration: Long-Pulse Photocoagulation, Apoptosis, and Heat Shock Proteins

To achieve a preselected temperature rise, TTT laser power must be increased or decreased in proportion to the diameter rather than the area of the laser spot. Clinical power settings should be adjusted for fundus pigmentation and media clarity because both of these factors affect absorbed retinal irradiance and thus retinal temperature rise. Noninvasive thermal dosimetry currently is unavailable for clinical retinal photocoagulation, but potential thermometric techniques include MRI, liposomal-encapsulated dyes, multispectral imaging or reflectometry, and subretinal or episcleral thermometry. TTT may be useful not only as independent therapy, but also as an adjunct to PDT, antiangiogenic drugs and ionizing radiation therapy in the management of neovascular ARMD. Low temperature, long-pulse photocoagulation is a potential strategy for decreasing neural retinal damage in subsequent TTT or short-pulse photocoagulation and perhaps even for treating glaucoma or retinal degenerations.