Delayed retinal effects of the frequency-doubled YAG laser (532 nm)

In order to compare the retinal effects of the frequency-doubled YAG laser (532 nm) with those of argon laser, rabbit eyes were exposed to green YAG laser irradiation and processed for light and electron microscopic study at 24 hr, 2 weeks and 4 weeks. Detailed analysis was conducted on tissue exposed to 7.3 and 7.6 millijoules (mj). Response of the photoreceptors and retinal pigmented epithelium to green YAG was very similar to that described for argon laser over the same time period. By 2 weeks post-exposure, there was histologic evidence of partial recovery with absence of damaged, pycnotic photoreceptor nuclei, increased numbers of typical photoreceptor outer segment lamellae and repair of retinal pigmented epithelium. Four weeks after irradiation, normal-appearing photoreceptor nuclei were present although inner photoreceptor segments still showed mitochondrial damage. Outer segments at 4 weeks showed regular lamellar structures. We conclude that the frequency-doubled YAG laser is equivalent to the argon laser with respect to the production of thermal lesions in the retina. Its additional advantages include increased efficiency, portability, reliability and lack of absorption by macular xanthophyll pigment.