Although seemingly innocuous, alcohol consumption disrupts the central nervous system diffusely and can have detrimental effects on multiple organ systems in both the acute and chronic phases.1
Of interest to eyecare providers, the eyes and vision are frequently vulnerable to the effects of alcohol use.2
How alcohol affects the eyes
After absorption into the body, alcohol can have toxic effects largely due to its metabolism to acetaldehyde and associated formation of reactive oxygen and nitrogen species.3
The depression in the central nervous system in acute intoxication can affect vision significantly, leading to blurred vision and poor fixation, among other symptoms.
Chronic alcohol consumption has been associated with a variety of conditions, including cataracts, macular degeneration, and optic neuropathy, among many other conditions across the eye. In severe cases, alcohol consumption can lead to permanent vision impairment.2
Therefore, it is important for eyecare providers to understand the impact of excessive alcohol consumption and promote healthy habits to patients from a unique perspective.
To learn more about ocular diseases related to alcohol consumption, check out An OD's Guide to Saturday Night Retinopathy!
Alcohol consumption: How much is considered toxic
Excessive alcohol intake is a significant public health challenge. Influenced by societal standards, alcohol is often consumed at a rate higher than recommended. Alcohol toxicity is dependent on individual factors, including age, sex, weight, and overall health.
Compared to excessive drinking, moderate drinking reduces the risk of negative health effects and is generally defined as two drinks or less per day for men and one drink or less per day for women, per the Centers for Disease Control and Prevention (CDC).4
Vision symptoms during acute alcohol intoxication
Alcohol consumption causes diffuse impairment in perceptual and cognitive processes; consequently, individuals may experience a variety of acute visual symptoms, including reduced visual acuity, decreased contrast sensitivity and color perception, diplopia, and abnormal eye movements.2
Due to impairment in cognitive processing, there may also be:5
- Latency in fixation
- Increased durations of fixation
- Increased frequency of saccades observed
Optic neuropathy following alcohol use
Chronic alcohol consumption can lead to alcohol-associated optic neuropathy, a subset of toxic and nutritional optic neuropathy. Patients may experience progressive, symmetric, bilateral central or cecocentral scotoma and color vision defects.6
Most authors suggest that dyschromatopsia may be the first symptom observed, with red hues appearing muted.7 Without modification in social behavior, visual acuity may also gradually decline. Atrophy in the papillomacular bundle may develop in later stages, leading to central scotomas and blurred vision.
The optic disc typically appears healthy in early stages, but can rarely be edematous and mildly hyperemic with acute intoxication. There may also be bilateral temporal disc pallor and splinter hemorrhages seen over time.6
Testing to determine damage
Ophthalmologic examinations should be performed at a frequency dependent on the degree of severity of signs and symptoms. It should include a dilated funduscopic examination with close attention around the optic nerves, central visual field testing for reduced sensitivity, and color vision evaluation for red-green or blue-yellow deficiencies.
Contrast sensitivity testing and optical coherence tomography (OCT) of the macula and optic nerve can also be considered if clinically indicated in later stages. Visual symptoms may recover over time with improvement in nutrition and reduction in alcohol consumption.6
Congenital issues due to alcohol consumption during pregnancy
Fetal alcohol syndrome is a condition that a child may develop due to prenatal alcohol exposure, which can lead to permanent physical and neurological effects. There is no safe threshold of alcohol that can be consumed; any amount can put a developing fetus at risk for the development of fetal alcohol syndrome.15
This can lead to widespread and permanent effects, leading to physical, cognitive, and behavioral problems in the child.15 For eyecare providers, it is important to know that fetal alcohol syndrome can cause the formation of cataracts, optic nerve and foveal hypoplasia, and strabismus.8
The child may also experience saccadic and fixation issues that are thought to be caused by frontal lobe dysfunction.8 Therefore, an initial ophthalmologic and binocular vision evaluation is recommended for children diagnosed with fetal alcohol syndrome.
OCT of the optic nerve and macula has been shown to have high sensitivity and specificity for detecting optic nerve hypoplasia and may be useful to aid in the clinical diagnosis.9
Long-term ocular effects of chronic alcoholism
Over time, chronic alcoholism can lead to issues across the eye and potential visual impairment:2
- Dry eye disease (DED): A history of heavy alcohol consumption and acute use of alcohol has been demonstrated to cause dry eye symptoms and a reduction in tear breakup time (TBUT) and Schirmer measurements.10,11
- Cataracts: Research suggests that there is an increased prevalence of cataract development among heavy alcohol consumers.12
- Impact on intraocular pressure (IOP): Chronic alcohol use has also been linked to elevated IOP in men, which potentially could have a downstream impact on glaucoma development.12
Although there may be a possible protective effect with moderate alcohol consumption, heavy alcohol consumption is thought to lead to the development of macular degeneration.12,13,14
Therefore, eyecare providers should closely examine a patient’s social history, especially if they present with any of these conditions, so that the condition can be managed as effectively as possible.
Conclusion
This article provides a summary of the impact of alcohol on the visual system. It is important for eyecare providers to educate patients so that they understand the role we play in the management of their holistic health as well as the effects of alcohol consumption on their eyes and vision.
In addition to a referral back to their primary care providers, eyecare providers should be aware of the national helpline via the Substance Abuse and Mental Health Services Administration (SAMHSA) and local rehabilitation centers that offer programs for recovery. A referral to a local dietitian may also be beneficial to improve their nutritional intake.
In patients who are at risk or have developed cataracts, macular degeneration, and other conditions, review their social history and discuss the impact of alcohol on their eyes if applicable.
In patients with seemingly inexplicable blurred vision and other symptoms outlined above, examine their optic nerves closely and perform visual field testing, color vision, contrast sensitivity, and OCTs as needed. At times, a patient’s social history can prove to be the key in identifying a potential cause for their visual complaints.
