INTRAOCULAR DYNAMICS OF DOGS EXPOSED TO NEAR-VACUUM PRESSURES.

Abstract : Four mongrel dogs were individually decompressed to 200 torr (200 mm. Hg, absolute) while breathing oxygen, and then rapidly decompressed to a near-vacuum pressure as represented by 2 torr for a 2-minute exposure. Observations of intraocular pressure and retinal appearance were made before exposure and after recompression to ground-level pressure. Increased intraocular pressure, engorgement of the central and peripheral veins, narrowing of the peripheral arterioles, paling of the disc and peripheral retina, and cupping of the disc were observed. Intravascular bubbles were not seen, but a small flame-type hemorrhage was seen in the eye of one animal. Retinal appearance tended to return to the pre-exposure state within about 45 minutes. The observed modifications appear to be of a temporary nature and probably do not account for the blindness or impaired vision that sometimes occurs in humans and lasts for several hours after accidental exposure to markedly reduced pressures. (Author)