Two Cases of Cortical Blindness after Gas Exposure

ABSTRACT

Cortical blindness is defined as the partial or complete loss of vision from bilateral lesions to the occipital cortex, with intact pupillary reflexes, normal fundi and extraocular movements. Although cerebrovascular disease is the most common cause of cortical blindness, cardiac surgery, cerebral angiography, eclampsia, head trauma, drug and carbon monoxide poisoning are causes too. Two patients with cortical blindness, following exposure to LNG (Liquefied Natural Gas) and argon gas are presented. Cortical blindness was thought to result from hypoxic or anoxic-ischemic change in the visual cortex, which is due to respiratory arrest from LNG intoxication and asphyxiating atmospheres from inhalation exposure to argon gas. Diagnosis was made with MRI scan showing bilateral occipital infarctions, which are the most valuable in diagnosing cortical blindness.