Macular photoagulation of human retina with a diode laser: a comparative histopathological study

Macular photocoagulation was performed on two human eyes with a diode laser emitting at 810 nm. The retinal burns were examined at 18 hours and five weeks following exposure and were found to be similar to those produced by krypton red irradiation. Unlike krypton laser exposures, no clinically visible choroidal hemorrhages were observed with diode irradiations. Damage was congined to the outer retina, retinal pigment epithelium and choroid. This was in contrast to the appearances seen following argon blue-green photocoagulation of the macula, in which inner retinal damage was observed associated with absorption by macular pigments. The implications of these findings will be discussed in relation to the potential advantages of treating common macular conditions with infrared diode lasers.