Alcohol retards visual recovery from glare by hampering target acquisition

Assessing the influence of cannabis and alcohol use on different visual functions: A comparative study

This study aimed to assess and compare the influence of alcohol intake and cannabis smoking on different visual functions. A total of 64 young and healthy volunteers took part in the study. All undertook several randomised experimental sessions in which different visual functions, namely distance stereopsis, retinal straylight, visual discrimination capacity, and contrast sensitivity, were tested. Cannabis smokers (N = 30) took a baseline session and a session after smoking a cannabis cigarette, whereas alcohol users (N = 34) underwent a baseline session, a session after a low alcohol intake (Alcohol 1), and a session after a moderate to high alcohol intake (Alcohol 2). All visual functions were impaired by cannabis and alcohol use, particularly for the Cannabis and Alcohol 2 groups. The deterioration of all visual variables was higher for the Alcohol 2 than for the Alcohol 1 and Cannabis groups, except for retinal straylight, the deterioration of which was equal for the Cannabis group, and distant stereopsis, which was more impaired for the Cannabis group. The Alcohol 2 group experienced the most impairing conditions, although very similar to the cannabis group, and that factors other than the experimental conditions, such as sex and age, also influenced these visual changes. Alcohol and cannabis use clearly impair vision. The deterioration caused by cannabis is similar to, but slightly lower than, that produced by a moderate to high alcohol intake, with the experimental conditions, sex and age all having an impact on the variability of visual deterioration.

Effect of glare on night time driving in alcoholic versus non-alcoholic professional drivers

Context:

The use of alcohol during nighttime driving may affect recovery from glare leading to increased traffic accidents.

Objective:

To compare the glare recovery time in alcoholic versus non-alcoholic drivers.

Materials and Methods:

Alcoholic (n = 25) and non-alcoholic drivers (n = 25) were subjected to glare recovery test and they also filled a questionnaire about the nighttime driving.

Results:

The glare recovery time got prolonged in alcoholic drivers and they also complained of more problems during nighttime driving as compared to non-alcoholic drivers.

Conclusions:

The use of alcohol delays recovery from glare during nighttime driving. This can have considerable implications for developing countries in improving regulations for driving licensing.

Measuring and predicting the effects of alcohol consumption on contrast sensitivity for stationary and moving gratings

Contrast sensitivity was measured for 12 healthy young males while sober, after ingestion of an alcohol placebo, and after ingestion of alcohol (95% grain alcohol; mean estimated blood alcohol level = .088%). Observations were made for both stationary gratings and gratings that traveled through a circular path and required pursuit eye movements. The significant alcohol-related reduction in contrast sensitivity was 2.6 times greater for moving (.29-log-unit reduction) than for stationary gratings (.11-log-unit reduction). The loss in contrast sensitivity for the moving gratings of high spatial frequency (12 cpd) was particularly severe (.37 log unit). Estimated blood alcohol level was correlated with the loss in contrast sensitivity for moving gratings (r = .61), but not with the loss for stationary gratings. Estimated blood alcohol level was strongly correlated with the difference between the loss in contrast sensitivity to moving and stationary gratings (r = .75). These results are consistent with reports that alcohol consumption degrades the ability to make pursuit eye movements. Subjects' perceived intoxication level was not a reliable predictor of any index of visual performance.

Psychomotor and visual performance under the time-course effect of alcohol

This study examined reaction time (RT), anticipation time (AT), and visual performance under the influence of blood alcohol concentration (BAC), using a repeated-measures design. Subjects (8 men and 8 women), 21 to 40 yr. of age, participated in both single- and double-dose sessions, in which they drank approximately 2.3 oz. and 4.6 oz. of 86-proof vodka, respectively. The breath BAC was measured at 5-min. intervals. The RT, AT, and visual performance were tested every 20 min. for 140 min. in both sessions. In general, results indicated that RT, AT, and stereoscopic vision were impaired more in the rising BAC curve than the falling BAC curve. In addition, the impairment tended to be greater for the double-dose than the single-dose session. The far and near visual acuities were not affected by the BAC.

Night driving (mesopic) visual acuity in sober male alcoholics with and without liver disease

Night driving (mesopic) visual acuity and recovery after dazzle has been reported to be reduced in patients with liver disease. Mesopic visual acuity and dazzle recovery were evaluated in 32 patients with alcoholic cirrhosis, 29 alcoholics without liver disease, and 27 age-matched normal controls. All subjects were sober for at least 7 days prior to visual testing, a mean sobriety period of 22 and 39 weeks in alcoholics and cirrhotics, respectively. Serum vitamin A levels and/or dark adaptation were normal in all. Mean best decimal acuities were not significantly different among the groups: alcoholic cirrhotics, 0.32 +/- 0.02; alcoholics, 0.32 +/- 0.02; and normals 0.33 +/- 0.03 at 2 min. Although cirrhotics had significantly higher SGOT and lower albumin levels than alcoholics, mesopic acuity did not relate to liver blood tests. Decimal acuity following a dazzle stimulus was not significantly worse in cirrhotics and alcoholics compared to normals. Sober patients with alcoholic cirrhosis or a history of alcoholism have no evidence of a static mesopic visual defect and therefore may not have impaired night driving vision.