Alcohol has various effects on the human body, including on the eyes. When a person is drunk, their eyes often take on a distinct appearance. In this article, we will explore the common signs of drunkenness that are visible in the eyes, why these changes occur, and what the changes indicate about a person’s level of intoxication. Understanding the ocular effects of alcohol can help you spot signs of drunkenness in yourself or others.
Bloodshot Eyes
One of the most well-known effects alcohol has on the eyes is causing them to become bloodshot or appear redder than normal. As a person drinks more alcohol, the tiny blood vessels on the surface of the eye expand and become dilated. This dilation causes the vessels to appear larger and more visible, giving the sclera (whites of the eyes) a diffusely red and bloodshot look.
Bloodshot eyes are a classic sign of intoxication and one of the first things people notice. In moderate intoxication, the redness may be relatively subtle. But in heavier intoxication, the sclerae can become quite red and almost seem to glow. The degree of redness corresponds with the person’s blood alcohol level.
So why does alcohol cause blood vessel dilation in the eye? It has to do with alcohol suppressing a hormone called anti-diuretic hormone (ADH). ADH constricts blood vessels throughout the body. When alcohol inhibits ADH release, blood vessels relax and widen. The small vessels in the eye are especially prone to showing this increase in size.
Other Causes of Bloodshot Eyes
While alcohol is a prime culprit for bloodshot eyes, other factors can also redden the eyes, such as:
- Allergies
- Dry eyes
- Pink eye (conjunctivitis)
- Smoke irritation
- Lack of sleep
So while bloodshot eyes are a good indicator of intoxication, be aware that other causes exist as well. The context of the situation will help determine if alcohol is the likely reason the eyes appear redder.
Glassy, Glossy Eyes
In addition to appearing bloodshot, drunken eyes often take on a glassy, glossy, or glazed-over look. Instead of the eyes looking clear and sharp, they seem unfocused, hazy, and vacant.
This glassy appearance has to do with alcohol’s effects on the muscles controlling eye movement and focus. Alcohol is a depressant that slows down signals from the brain to the muscles. This delayed reaction causes the eyes to lose precision in their small muscle movements.
The eyes drift more easily and have trouble maintaining visual fixation. This compromised muscle control gives the eyes a disconnected, glazed over, staring look. The more intoxicated someone is, the less control they have over their eye muscles and the glassier their eyes will seem.
Other Causes of Glassy Eyes
While glassy eyes are strongly associated with intoxication, other conditions can sometimes produce a similar appearance, such as:
- Extreme fatigue
- Drug use
- High fever
- Head injury
- Certain medications
Again, consider the circumstances to determine what might be causing the glassy eyed appearance. But in the context of drinking or a party environment, glassy eyes are a telltale sign of alcohol impairment.
Droopy, Heavy Eyelids
Alcohol has a sedating effect on the body that can cause the eyes to appear tired and heavy lidded. The eyelids droop and may close or nearly close, giving the appearance that the person is nodding off. With moderate to high doses of alcohol, the drinker may struggle to keep their eyes fully open.
This sedative effect relates to alcohol being a central nervous system depressant. It inhibits brain activity in areas that control arousal and wakefulness. As drinkers become drowsier, their eyelids reflect this by appearing low and heavy.
Droopy eyelids are not an early sign of intoxication. They indicate the drinker has reached a more significantly impaired state. Closing the eyes for prolonged blinking or brief nodding off are further signs that the person may pass out or “black out” from too much alcohol consumption.
Other Causes of Droopy Eyelids
Some other causes can produce droopy eyelids besides alcohol, including:
- Normal drowsiness
- Sleep disorders
- Facial paralysis
- Eye injuries
- Skin disorders
- Certain medications
But in the context of drinking, heavy eyelids are a reliable indicator that alcohol is taking its sedative effect. Droopy eyelids mean the drinker is likely quite impaired.
Inability to Converge Eyes
A more subtle sign of intoxication is difficulty converging the eyes properly and maintaining binocular vision. To focus on objects up close, the eyes must turn inward and align simultaneously. This is called converging the eyes.
But alcohol inhibits this coordinated eye movement. A drunk person will struggle to cross their eyes when looking at a finger placed close to their face. One or both eyes may turn outward instead of inward, causing double vision.
This inability to converge the eyes is due to alcohol’s effects on the ocular muscles and impaired depth perception. Tests of eye convergence are sometimes used by police officers during field sobriety testing.
Other Causes of Failure to Converge
Other conditions can also cause difficulty converging the eyes, including:
- Nerve damage
- Graves disease
- Brain injury
- Eye muscle weakness
But when impairment is already suspected, failure to cross the eyes properly can support the presence of high intoxication.
Nystagmus
Nystagmus is the medical term for abnormal, jerky eye movements. This involuntary eye shaking motion happens naturally as the eyes change fixation. But alcohol intensifies nystagmus.
As someone becomes more impaired by alcohol, their eyes exhibit nystagmus to a greater degree. The eyes visibly jitter and dance as they struggle to fixate. This is another sign evaluated in field sobriety testing by police.
Alcohol magnifies nystagmus by further interfering with the brain’s ability to control eye muscles. Nystagmus onset can begin with even modest intoxication levels. As BAC rises, the eye shaking becomes more pronounced.
Severe nystagmus is a strong indicator that the drinker is highly intoxicated. The motion is usually horizontal, with eyes jerking rapidly side-to-side. But sometimes alcohol causes a vertical nystagmus, with the eyes bobbing up and down. This type often indicates a dangerously high BAC.
Other Causes of Nystagmus
While alcohol is a major cause of nystagmus, some other conditions can also trigger eye shaking, like:
- Head injuries
- Stroke
- Multiple sclerosis
- Migraines
- Certain medications
Context is key to identifying intoxication as the likely cause. Nystagmus when drinking alcohol is a strong red flag of impairment.
Unequal Pupil Size
Normally, the eye’s pupil size constricts and dilates equally. But in drunkenness, alcohol can cause unequal or asymmetric pupil dilation.
One pupil may become noticeably larger than the other, or one remains constricted while the other dilates. This imbalance results from alcohol depressing nerve signals that coordinate the pupil muscles.
In later stages of high intoxication, the pupils also demonstrate a sluggish response to light. They resist promptly constricting when exposed to brightness. This delay indicates the nervous system is significantly depressed by alcohol.
Unequal pupil size doesn’t happen with moderate drinking. It’s a manifestation of binge drinking or acute alcohol poisoning. If someone’s pupils are asymmetric and nonreactive to light, seek emergency medical care for them.
Other Causes of Unequal Pupils
While substance abuse can cause uneven pupils, some other conditions may also produce this effect:
- Head trauma
- Stroke
- Tumor
- Infection
- Nervous system disorders
But in the context of heavy drinking, unequal pupil dilation is an emergency sign of severe intoxication.
Blinking and Gaze Fixation Problems
Two other eye behaviors affected by alcohol are blinking and gaze fixation. Blinking helps moisten eyes and clear away debris. Gaze fixation maintains visual focus on specific objects.
Alcohol disrupts both these eye functions. A drunk person may blink erratically, rarely, or slowly. Staring spells also increase as gaze fixation weakens. The eyes can take on a staring, nonblinking appearance.
With extreme intoxication, the blink reflex may stop completely for stretches, with eyes remaining wide open and fixed. These behaviors relate to how alcohol impedes brain signaling to the muscles controlling eye function.
Abnormal blinking and gaze are not early signs of drinking. They emerge later as intoxication increases and nervous system control continues to falter. If someone cannot seem to blink or their stare remains locked in place, urgent medical help may be needed.
Other Causes of Blinking/Gaze Problems
Abnormal blinking and stare may also derive from:
- Tourette’s syndrome
- Parkinson’s disease
- Bell’s palsy
- Dry eyes
- Brain injuries
But impaired blinking or gaze fixation while drinking alcohol are red flags of worsening intoxication. Seek emergency care if these persisting eye issues arise.
Eyelid Ptosis
Ptosis is a condition where the upper eyelid droops down over part of the eye. With alcohol inebriation, ptosis can sometimes occur on one or both sides. This happens from the relaxing effects of alcohol on the muscles controlling eyelid elevation.
Ptosis may come and go during drinking, briefly dropping one eyelid lower before recovering. Chronic heavy drinking can lead to permanent acquired ptosis over time.
Like droopy eyelids, ptosis from alcohol emerges during advanced stages of intoxication. Mild ptosis can be part of normal aging, but ptosis plus other ocular signs indicates severe drunkenness.
Other Causes of Ptosis
Besides alcohol abuse, ptosis can also stem from:
- Congenital defect
- Nerve damage
- Head/eye injuries
- Eyelid tumors
- Neurological conditions
In a drinking context, acquired ptosis is a distinct flag of high intoxication levels.
Conclusion
The eyes can reveal a lot about a person’s level of alcohol impairment. Bloodshot eyes, glassy appearance, and droopy lids emerge as intoxication rises. Nystagmus, pupil changes, and gaze problems occur in advanced drunkenness.
While various eye conditions mimic these signs, when drinking is involved the ocular effects point to progressively worsening inebriation. Understanding how alcohol impacts eye structure and function can help assess sobriety in social situations. With awareness of these effects, alcohol-related health emergencies can hopefully be prevented.