Alcohol and marijuana effects on static visual acuity

Static visual acuity was measured at two contrast levels (12 and 49%) in ten subjects in a double blind experiment involving five drug conditions of alcohol and marijuana (0.5 ml and 1.0 ml/kg body weight of 95% ethanol, 8 and 15 mg delta-9-tetrahydrocannabinol (THC), and a placebo). We found no statistically significant change in static visual acuity for any of the dose levels at any of the measurement time up to six hours following drug ingestion; this is sharply contrasted with the marked decrements in acuity which were found in the same subjects under the same drug conditions when the targets were in motion and required corrdinated eye movements for their resolution.