Having glassy eyes typically means your eyes look shiny or glazed over. This often makes the eye appear as though it’s unfocused.

Read on to learn about the various causes, ranging from everyday to severe.

1. Intoxication

Glassy eyes can be caused by intoxication with various substances, including prescription medication and illegal substances. This is because these substances often affect the central nervous system, slowing the body’s ability to regulate functions that seem automatic to us like blinking. If a person takes longer to blink, their eyes become dry and glassy.

Of all drugs, glassy eyes are most commonly associated with marijuana and heavy alcohol use. Other symptoms of intoxication vary widely, but can include slurred speech, imbalance, drowsiness, and argumentative behavior.

A doctor can typically diagnose intoxication using blood, breath, and urine tests. The treatment for intoxication is time — a person has to wait for their body to detox a drug to see alleviation of symptoms.

2. Allergies

Eye allergies can cause your eyes to get red, itchy, teary, and glassy. Allergies can be caused by:

  • pollen
  • dust
  • pet dander
  • products you use in or around your eye

Generally, removing the allergen will decrease your symptoms. You can also treat allergies with over-the-counter medications, like loratadine (Claritin) or diphenhydramine (Benadryl), and eye drops.

3. Dehydration

In children, dehydration can cause glassy eyes. Other symptoms of dehydration are dry mouth, excessive thirst, and lightheadedness. Mild dehydration can be treated at home by consciously drinking more water, but severe dehydration needs to be treated via fluid administered through an intravenous (IV) line at a medical clinic or hospital.

Symptoms of severe dehydration in children include:

  • extreme sleepiness
  • lack of saliva
  • extremely dry mouth
  • six to eight hours without urinating

4. Dry eyes

Dry eyes occur when your tear glands aren’t able to produce lubrication for your eye. This can happen if your tear glands don’t produce enough tears or if they produce low-quality tears. Dry eyes are also a possible symptom of eye surgery or of blinking infrequently, like after staring at a computer for too long.

5. Conjunctivitis

Also known as pink eye, conjunctivitis involves an inflamed conjunctiva, a thin layer of tissue that covers the white part of the eye and inner eyelid. Conjunctivitis can be viral, bacterial, or allergic. Pink eye is known for causing the eye to turn red, appear glassy, and possibly have white pus or a crust form around it.

6. Cholera

Cholera is a bacterial infection that causes severe dehydration. Cholera isn’t common in the United States. It does occur in:

  • Africa
  • Asia
  • India
  • Mexico
  • South and Central America

The bacteria that cause cholera are typically spread through contaminated water. Besides glassy eye, other symptoms include vomiting and diarrhea. Cholera is deadly, but it can be treated with rehydration and antibiotics.

7. Herpes

The same strain of the herpes simplex virus that causes cold sores near the mouth (HSV type 1) can also, in some cases, affect the eye. HSV type 1 can cause your eyes to become red, appear glassy, tear excessively, and become sensitive to light. It can also cause your eyelids to develop blisters.

The varicella zoster virus (VZV) is from the same family as HSV and can also affect the eye. Normally, VZV causes chicken pox and shingles. Symptoms of ocular VZV are similar to those of HSV type 1, but also include the symptoms of chickenpox or shingles.

8. Graves’ disease

Graves’ disease is an autoimmune disorder. A symptom of Graves’ disease is the appearance of enlarged eyes. Called Graves’ ophthalmopathy, this occurs when the eyelid retracts. Because of this, your eyes may become dry and glassy. Other symptoms of Graves’ disease include a swollen neck, weight loss, and thinning hair.

9. Hypoglycemia

Low blood sugar, also known as hypoglycemia, commonly occurs in people with diabetes. Symptoms of low blood sugar include:

  • sweating
  • lightheadedness
  • pale skin
  • shaky or jittery hands
  • blurred vision

When your blood sugar levels are too low, eating something made of carbohydrates is key. Severely low blood sugar that isn’t treated can cause serious complications.

Treatments for glassy eyes vary depending on the cause. In the case of dry eye, using eye drops may help solve the problem. Eye allergies can be treated by removing the allergen or taking antihistamines.

In other cases, such as with herpes or pink eye, your eye doctor may recommend taking antiviral medication or using antibiotics. It’s important to see your doctor and note any other symptoms you having so you can get the right treatment.

1. Limit screen time

Staring at computers and other device screens for too long has been known to strain the eyes. To avoid tiring your eyes and causing glassy eye, limit your exposure to looking at screens.

Another prevention method is ensuring the screen is far enough away from your face. According to the American Optometric Association, a computer screen should be 4 – 5 inches below eye level and 20 – 28 inches from the eye.

The association also recommends resting your eyes once every 15 minutes after two hours of ongoing use of a computer. To rest your eyes, simply look at an object 20 feet away for 20 seconds or longer. Find out more about the 20-20-20 eye rule.

2. Drink more water

Ensuring your body gets enough water per day — at least eight glasses of 8 oz. of water — is ideal. Here, we break down how much water you really need per day and tips on how to get it.

3. Don’t share

According to the National Eye Institute, people should avoid sharing anything that may come in contact with their eyes and spread bacteria or irritants. This includes:

  • cosmetics, such as eye makeup and face makeup
  • eyeglasses or sunglasses
  • towels, blankets, and pillowcases
  • eye drop bottles

4. Wash your hands

Dirty hands are one of the easiest ways to spread germs and eye irritants. If you’ve interacted with someone with an eye condition such as conjunctivitis, it’s important to wash your hands regularly to avoid spreading the condition. People who wear contacts should also wash their hands before putting in or removing contact lenses.

5. Visit your eye doctor

Just as you should visit your general practitioner once a year for a checkup, you should also visit your eye doctor annually. These routine visits can help your doctor assess your eye health or catch eye conditions early. These visits can also help you better understand your eyes, what causes symptoms like glassy eyes, and encourage you to build good habits that promote eye health.