Effects
of Alcohol on Vision
Consuming
alcohol can have short-term negative affects on vision. For a low blood alcohol
level, visual performance is less affected by the visual changes than by
alteration in brain functions [1]. Brain functions can be impaired by alcohol
within minutes of consumption since alcohol is absorbed in the blood and the
brain is supplied with more blood than other organs.
When
the legal blood-alcohol level is reached and surpassed, depth perception and
night vision are affected. It becomes
impossible to accurately judge how far away objects are when depth perception
deteriorates. Vision becomes blurred or
you may see double since eye muscles lose their precision causing them to be
unable to focus on the same object.
Alcohol
affects night vision by keeping the pupils from adapting from darkness to
light. The oncoming headlights of a car
will cause a drunk driver to be dazzled much more severely than a sober driver. Alcohol consumption also produces tunnel
vision and can make night blindness worse [2].
Contrast
sensitivity can be reduced preventing an intoxicated driver from detecting
obstacles in his field of view in some situations. A reduction in contrast sensitivity combined with changes in
ocular-motor control and attention deficits may have a strong effect on
performance while under the influence of alcohol [3]. During the daytime, under
normal driving conditions, reduction in contrast sensitivity might not cause
any problems. In more unfavorable
conditions, such as fog or at night, alcohol can reduce the visibility of an
object to the point of being below the threshold of detectability. Under conditions where an object is moving
rapidly with respect to the driver or flickering quickly this deficit is likely
to be enhanced [4].
Alcohol
adversely affects performance on many tasks. At moderate blood alcohol levels
and possibly lower levels, a slowed perceptual speed is a component of the task
performance [5].
Sometimes
seminars are given by local fire or police departments for high school and
college students where “Fatal Vision” goggles are used to simulate some of the
effects that alcohol has on vision.
These goggles give the wearer a blurred and distorted impression of the
world around them. When asked to do
simple tasks such as dribbling a basketball the goggles made it almost
impossible which hopefully leaves a lasting impression of how severely vision
can be affected [6].
There
is one eye disorder called tobacco-alcohol amblyopia in which, as the name
suggests, alcohol and smoking are believed to be contributing factors.
“Clinical evidence exists that a nutritional
deficiency is the underlying cause of this condition; however, many observers
still believe that the toxic effects of alcohol and tobacco are contributing
factors.
Most patients with tobacco-alcohol amblyopia suffer
from severe nutritional depletion, and visual improvement in these patients
seems to be related to improved nutrition rather than to abstinence from
alcohol. Visual improvement has been observed in patients treated with large
does of vitamin B complex who have continued their usual intake of alcohol or
continued smoking. A nutritional etiology still cannot be discounted when
administration of B vitamins failed to produce improvement, because the
degenerative process may have become irreversible by the time treatment was
initiated.” [7].
Wine consumption may lower, rather than raise, the risk of developing age-related macular degeneration (AMD). The findings of one research project show that wine drinkers were 20% less likely to develop AMD than non-drinkers or beer or liquor drinkers [8]. Thus, vision could be affected in a positive way with long-term moderate wine consumption. According to the report, the risk of the elderly contracting macular degeneration, which is an eye disease that can cause blindness, could be lowered from small amounts of wine such as just one glass each month [9].
References:
1. Effects of low alcohol consumption on visual evoked potential, visual field and contrast sensitivity. Quintyn JC; Massy J; Quillard M; Brasseur G ACTA OPHTHALMOLOGICA SCANDINAVICA. vol. 77, no. 1 (1999 Feb): 23-6.
PURPOSE: We studied changes in the vision of 16 people after consumption of a small of alcohol, at a blood alcohol level (BAL) of 0.57 g/kg.CONCLUSION: These results suggest for a low blood alcohol level, visual performance is less affected by the visual changes than by alteration in brain functions.
2. http://www.transport.gov.za/projects/arrive/alcohol98.html
3. Effects of moderate blood alcohol concentrations on spatial and temporal contrast sensitivity. Pearson P; Timney B JOURNAL OF STUDIES ON ALCOHOL. vol. 59, no. 2 (1998 Mar): 163-73.
OBJECTIVE: In order to gain a more complete picture
of the influence of alcohol on visual performance, we measured contrast
sensitivity for a range of spatial and temporal frequencies in individuals with
moderate blood alcohol concentrations (BACs). CONCLUSIONS: These data suggest
that alcohol produces visual deficits that are not attributable to pursuit eye
movements. It is suggested that these visual deficits, combined with changes in
ocular-motor control and attentional deficits, may have a strong effect on
performance under the influence of alcohol.
4. http://www.druglibrary.org/schaffer/Misc/driving/s30p4.htm
5. Effects of alcohol on perceptual speed. Jones MB; Chronister JL; Kennedy RS PERCEPTUAL AND MOTOR SKILLS. vol. 87, no. 3 Pt 2 (1998 Dec): 1247-55.
In moderate to heavy doses, alcohol adversely affects performance on many tasks, and perceptual speed is a component in most performance tasks. 16 men and12 women were administered four temporal-factors tests before and after the ingestion of alcohol. At moderate BACs and possibly at lower ones, the effects of alcohol on task performance appear to be mediated in part by slowed perceptual speed.
6. http://www.nnsl.com/frames/newspapers/archive98-1/may98/may15_98drunk.html
7.
Spencer, William H. M.D., Ophthalmic
Pathology: An Atlas and Textbook, Third
8. Risk of age-related vision loss wanes with wine. Lancet; SCIENCE AND MEDICINE NEWS (1998 Jan): 117