Retinal damage experimentally induced by microwave radiation at 55 mW/cm2

The action of 550 W/m2 (mean) 3100 MHz pulsed radiation on the rabbit retina in vivo was investigated by fundus photography, blood-retinal barrier tracers, light and electron microscopy, either after a single 1--1.5 h exposure or after a series of repeated 1 h exposures for up to 53 h during about 100 days. The electron microscopic investigation of the repeatedly exposed retinas revealed degenerative changes in the retinal neurons. The neurons appeared depleted of their cytoplasmic constituents and often contained phago-lysosomal structures with myelin bodies. There were many degenerating synaptic boutons. The glial cells displayed reactive changes. These ultrastructural changes could not be demonstrated by the other methods used. A single microwave exposure, followed by an induced 70--100% blood-pressure increase, did not enhance blood-retina barrier permeability to tracers. There was no evidence of blood brain barrier leakage. These studies show that the rabbit eye can be affected by microwave radiation at intensities lower than previously reported.