ABSTRACT
One case of unilaterally developed acute retinal necrosis syndrome was studied with retina and vitreous from biopsy during operation through electronmicroscope pathologically and virolo gically. In photoreceptor cells, generalized necrosis was found: loss of outer segments, fragmentation of inner segments, and decrease of mitochondria in ellipsoids. Bipolar cells and axons were well preserved. Internal limiting membrane was intact, and covered by an unidentified cell. Degenerated retinal proper had various sized vacuoles. Around the intraretinal vessels, neutrophils and lymphocytes were infiltrated considering vasculitis. In ganglion cells, swelling of mitochondrias were seen, and their cell organelles were decreased, No virus particle was detected in all layers of the retina with electronmicroscope.