Microwave-induced retinal destruction with sparing of sclera and choriocapillaris.

We studied the effect of short-term hyperthermia on sclera, choroid, and retina by delivering microwave radiation (2.45 GHz) for 1 minute to 12 eyes of Dutch belted pigmented rabbits. Four eyes each were treated with 43 degrees C, 45 degrees C, and 47 degrees C and followed for 4 weeks. The 43 degrees C group showed minimal disruption of retinal pigment epithelium and outer retina, with pigment migration; the 45 degrees C and 47 degrees C groups showed complete retinal and RPE damage, pigment migration, and glial proliferation. At the same time, the sclera and choroid in all of the eyes remained essentially unchanged. We conclude that microwave-induced hyperthermia can create retinal scarring without significant damage to sclera and choriocapillaris. The next experimental step will be to refine the microwave delivery system to ensure predictable and reproducible lesions.