Red eyes are a common occurrence that may be bothersome but often painless. Your eyes appear red when blood vessels in the conjunctiva (transparent tissue covering the whites of the eye) become enlarged. While some conditions are self-resolving, others are more severe or require treatment.
Common Causes of Red Eyes
Here are some typical conditions that cause eye redness:
Dry eye disease
Dry eye disease (DED) affects nearly 75% of adults over age 40, making this condition one of the most frequent causes of red eyes.
Eye symptoms include:
- Light sensitivity
- Intermittent blurry vision
Many factors influence DED:
- Medications such as antihistamines, oral contraceptives, isotretinoin (Accutane), antidepressants, and many other drugs cause dry eyes.
- Systemic diseases like diabetes, rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus, thyroid disease, and other inflammatory or autoimmune conditions often contribute to DED.
- Hormonal changes, particularly in postmenopausal women, can increase dryness.
- Environmental conditions such as humidity levels, air conditioning or heaters, and sun exposure also affect how dry your eyes feel.
- Other factors include contact lens wear and excessive screen time.
There are various treatments for DED:
- Eye drops may be over-the-counter lubricating drops or prescribed medications such as cyclosporine (Restasis), lifitegrast (Xiidra), steroids, and autologous serum (drops made from your blood).
- Oral supplements and medications include omega-3 fish oil and antibiotics.
- At-home therapy such as eye masks, humidifiers, and hot compresses.
- In-office treatments such as eyelid gland expression (unclogging blocked oil glands), punctal occlusion (blocking tear drainage ducts to retain tears), and intense pulsed light therapy.
Allergic conjunctivitis occurs after exposure to allergens like pet dander, pollen, or mold. As a result, your eyes can develop a reaction with:
- Swollen eyelids
- Stringy discharge
The best thing to do is to avoid or limit exposure to the allergen. If you are not sure what is causing the reaction, talk to your doctor about allergy testing.
For symptomatic relief, you can try:
- Allergy eye drops, such as olopatadine (Pataday), alcaftadine (Lastacaft), and ketotifen (Zaditor).
- Oral allergy medications are often helpful, which include diphenhydramine (Benadryl), fexofenadine (Allegra), loratadine (Claritin), and cetirizine (Zyrtec).
- Use cool compresses to reduce swelling and soothe the eyes.
- Lubricating drops help flush allergens out of the eye.
Many people associate the term “pink eye” with eye infections. Most eye infections in adults are viral conjunctivitis, while nearly 75% of cases in children are bacterial.
Symptoms of viral, bacterial, and allergic conjunctivitis can be similar:
- Eyelid swelling
- Light sensitivity
However, viral infections tend to have watery discharge, bacterial infections typically have thicker green or yellow mucus, and allergic conjunctivitis has stringy, white discharge. Your eye doctor can examine your eyes in detail to determine the root cause.
Viral and bacterial conjunctivitis typically resolve within 2 weeks without treatment. There is no specific treatment for viral conjunctivitis, but lubricating drops and cool compresses may provide symptomatic relief. Bacterial conjunctivitis may not need treatment, but your doctor may prescribe antibiotic drops or ointment to speed up healing.
Both conditions are highly contagious, so good hygiene is extremely important to avoid spreading the infection.
A subconjunctival hemorrhage occurs when a blood vessel under the conjunctiva ruptures. As the blood spreads, the appearance can be alarming as the eye often looks bloodshot red.
Most subconjunctival hemorrhages are associated with:
- Forceful actions such as coughing, sneezing, weightlifting, and straining.
- Eye trauma, which can include rubbing your eyes vigorously.
- Use of aspirin or other blood thinners.
- In rare cases, recurrent subconjunctival hemorrhages may indicate blood clotting disorders.
Fortunately, this condition is painless and usually resolves in 2 to 3 weeks without treatment.
Infrequent Causes of Red Eyes
Less common causes of redness include:
Uveitis is inflammation of the middle layers of the eye (uvea). Symptoms of uveitis are:
- Eye pain that radiates through the head
- Red eyes
- Light sensitivity (can be severe)
- Blurry vision
The cause of uveitis may be unknown, but in other cases, it may be associated with:
- Autoimmune diseases such as systemic lupus erythematosus, inflammatory bowel disease, sarcoidosis, rheumatoid arthritis, and Behcet's disease.
- Multiple sclerosis.
- Eye trauma or surgery.
- Infections like herpes zoster virus (cold sores), varicella zoster virus (chickenpox and shingles), syphilis, toxoplasmosis, and tuberculosis.
- Rarely, cancers such as lymphoma or leukemia.
Uveitis requires treatment with steroid eye drops, injections, or oral medication. Steroids work to reduce inflammation. Some people have to use steroid drops long-term to prevent recurrence of uveitis. Your doctor must also treat any underlying causes such as infections or cancer (which can be life-threatening).
Episcleritis and scleritis
Episclera is a layer of tissue between the conjunctiva and sclera (whites of the eye). Inflammation of this tissue is called episcleritis, which causes:
- Redness (either in one section or the entire white part of the eye)
- Mild pain
- Swelling of the eye and eyelids
The exact cause of episcleritis is unknown. However, approximately one-third of cases are associated with inflammatory conditions like rheumatoid arthritis, inflammatory bowel disease, and systemic lupus erythematosus. Episcleritis may resolve without treatment. If needed, your doctor may prescribe nonsteroidal anti-inflammatory drugs (NSAIDs).
Scleritis, or inflammation of the sclera, is more severe than episcleritis. Symptoms can be similar, but scleritis also causes:
- Deep, violet-red color of the sclera
- Severe pain
- Decreased vision
- Light sensitivity
Scleritis is less common than episcleritis, with 4 cases per 100,000 people. Scleritis is associated with systemic autoimmune disease, eye surgery, or infection (herpes zoster virus is most common). Treatment for scleritis usually involves steroids, NSAIDs, or immunosuppressive drugs.
Angle-closure glaucoma occurs when the drainage structure of the eye closes up, resulting in a buildup of fluid in the eye and a rapid increase in eye pressure.
Unlike other glaucomas that are asymptomatic, angle-closure glaucoma causes:
- Eye and head pain
- Nausea and vomiting
- Light sensitivity
- Hazy vision
Angle-closure glaucoma requires prompt treatment to lower eye pressure with oral and topical medications. Then, your eye doctor may perform laser or surgery to prevent angle closure from recurring. Without medical attention, this condition can cause permanent damage to your vision.
If you are unsure what is causing your red eye, consult your eye doctor. They can prescribe proper treatment and diagnose underlying causes that may be vision- or life-threatening.
Small glands located above the eyes produce tears. They function to lubricate and protect the eyes. When your eyes don't produce enough tears or tears are of poor quality, you have dry eyes.
The blood vessels inside your injured eye enlarge and dilate. Blood and cells are sent to the wounded location by the dilated blood cells to aid in healing.
Mast cells, which are found in your eyes, are stimulated by certain allergens to release histamine and other compounds that may cause inflammation.
Allergies, insufficient sleep, excessive drink or drug use, smoking, or dry eyes are among the major causes of red eyes. Blepharitis, conjunctivitis, trauma, or glaucoma are some of the other conditions that can produce red eyes.
Additionally, little bags of frozen peas or corn work well as red eye compresses since they mold to the eye area and keep the area cooler longer than a cloth would.
While some cases of red eyes can be treated at home, many others necessitate medicine and other types of prescribed care. Visit your eye doctor to find out the source of your bloodshot eyes and to get the best possible treatment options. This is the best and safest technique to get rid of red eyes. Remove your contact lenses (if you wear them) and switch to your glasses until you can see your eye doctor about your red eye issue. Additionally, bring your contacts to your appointment so your doctor can determine whether they are the cause of your red eyes.
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Home Healthcare Now. Dry Eye Disease: Prevalence, Assessment, and Management.
The Journal of the American Medical Association. Conjunctivitis: A Systematic Review of Diagnosis and Treatment.
Review of Optometry. A Red Eye: Scleritis or Episcleritis?
StatPearls. Acute Closed Angle Glaucoma.