Carbon disulfide effects on the visual system. I. Visual thresholds and ophthalmoscopy.

The visual effects of carbon disulfide exposure were studied in macaque monkeys with measurements of visual thresholds, fluorescein angiography and fundus photography. Five monkeys were exposed by inhalation for 6 hr a day, 5 days a week to 256 ppm carbon disulfide (CS2). The motor dysfunction observed in these monkeys appeared to be entirely reversible. All five suffered severe reductions in visual acuity and contrast sensitivity although flicker resolution was not affected. Visual loss was found to be irreversible, with degeneration of substantial numbers of retinal ganglion cells (companion paper) in those monkeys permitted to survive after the termination of exposure. None of the monkeys developed retinal microaneurysms or hemorrhages, major accepted signs of visual toxicity in CS2 exposed humans; thus, permanent visual loss may result from carbon disulfide exposure even in the absence of retinal vascular effects.