Eye pain can have a variety of causes. It is typically divided into conditions that affect the cornea, conditions that affect of other parts of the eye, and conditions involving other areas of the body that cause pain to be felt in the eye area.

Common causes of eye pain typically center around particular parts of the eye. These include the cornea, the white of the eye (sclera), and a thin layer that covers it called the conjunctiva. The colored part of the eye is the iris.

The muscles that control the eye, the nerves, and the eyelids can also be sources of eye pain.

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The cornea keeps dirt and germs out of the eye and also filters UV light from the sun.

A problem with the cornea is the most common cause of eye pain. The cornea is the outermost layer of the eye. It has a clear dome-shaped surface that covers the front of the eye.

Many disorders that affect the cornea also affect the fluid-filled space between the iris and the inner part of the cornea.

The cornea acts as a direct barrier keeping out dirt, germs, and other harmful or foreign particles that could harm the eye. The cornea is also very helpful in filtering out damaging ultraviolet light (UV) from the sun.

Corneal disorders include:

  • Herpes simplex keratitis: An eye infection caused by the herpes simplex virus.
  • Bullous keratopathy: An eye disorder marked by blister-like swelling of the cornea. Blisters can rupture causing severe pain, eye discomfort, and vision impairment.
  • Peripheral ulcerative keratitis: An eye disorder that causes inflammation and ulceration of the cornea. Typically occurs in people who have connective tissues diseases, such as rheumatoid arthritis.
  • Corneal ulcer: An eye infection that causes an open sore on the cornea. Contact lenses, injuries, drugs, and nutritional deficiencies can cause open sores. Ulcers cause pain, redness, and tearing.

Just like other body parts, the cornea can heal from minor injuries or scratches. The area usually heals on its own with no lasting impact on vision.

Deeper injuries can cause corneal scarring resulting in a haze on the cornea that can impair vision. People who have a deep injury or corneal disease may experience:

  • pain in the eye
  • sensitivity to light
  • reduced vision or blurry vision
  • redness or inflammation in the eye
  • headache
  • nausea or fatigue
  • bulging of an eye
  • inability to move eye in all directions

People who have corneal disease or damage may experience pain, tearing, and a decrease in the sharpness of their vision.

Anyone experiencing any of these unusual eye symptoms should contact an eye professional immediately. Corneal disease or other eye disorders can only be diagnosed after a thorough eye examination.

A slit lamp is commonly used to examine the cornea and eye area. This instrument allows the doctor to examine the eye under exceptionally high magnification. Eye drops called fluorescein may be used to provide a temporary stain to the areas of the cornea, making it easier for the doctor to see.

Doctors may even scrape the surface of large ulcers present in the eye to obtain a sample. The sample is cultured and used to identify whatever is causing the infection.

Once the cause has been identified, the doctor can decide on the best drug to fight the infection. Common eye treatment includes:

  • antibiotic or antifungal drops
  • pain relief with eye drops, oral drugs, or both
  • removal of foreign bodies
  • transplantation of the cornea

Abrasions and foreign objects

The most common injury to the cornea is due to abrasions caused by foreign objects.

Abrasions can be caused by:

  • particles from the wind
  • working with tools or any other type of debris
  • fingernails
  • contact lenses
  • make-up applicators

Once the foreign objects are removed, they may leave minor scratches on the cornea. The surface cells of the eye grow back rapidly, so most scratches usually heal within 1 to 3 days.

However, a medical evaluation can determine if the cornea is scratched and prompt treatment with antibiotics can prevent an infection.

Pain relief medication in the form of eye drops is also routinely prescribed.

A follow-up examination by an eye specialist after the injury is also recommended.

Glaucoma occurs when an imbalance in production and drainage of fluid in the eye causes pressure in the eye to increase to unhealthy levels. This raised pressure causes progressive optic nerve damage, which can eventually lead to irreversible loss of vision.

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Glaucoma is a common cause of blindness so early detection is important. It may develop suddenly and cause intense eye pain and red eye.

People may experience eye redness, discomfort, blurred vision, or headaches, but loss of vision due to glaucoma occurs slowly and may go undiagnosed for a long time. Vision loss is permanent, so early detection is key.

Once diagnosed, however, vision loss can be prevented with proper treatment. A person may be prescribed eye drops containing beta-blockers or other compounds to decrease the eye pressure.

The type of treatment depends on the severity of glaucoma. Surgery may be required if the eye pressure is extremely high or if eye drops have not been effective. Doctors may increase drainage in the eye or even create a new drainage system.

Those at high risk for glaucoma should have a comprehensive eye exam every 1 to 2 years. Doctors will measure eye pressure or use an instrument called a tonometer. They also use a tonometer to look for any changes in the optic nerve that could indicate damage from glaucoma.

Glaucoma is the second most common cause of blindness in the world and people over the age of 60 years are six times more likely to develop glaucoma than other people.

Uveitis refers to inflammation located anywhere in the pigmented lining of the eye. This section of the eye is called the uvea or uveal tract.

The area can become inflamed due to infection, injury, or an autoimmune disorder. In some cases, the reason for the inflammation may be unknown.

Symptoms of uveitis include:

  • eye ache
  • redness in the eye
  • loss of vision or blurry vision

Uveitis can be diagnosed during a physical examination using a slit lamp. Uveitis can cause permanent damage to the eye, so the disorder should be treated as early as possible.

Treatment typically includes corticosteroids, usually in the form of eye drops. Drugs to dilate the pupils, other drug therapies, and even surgery may be needed.

Endophthalmitis is an eye infection caused by organisms that have entered the eye through a surgical incision or an injury to the eyeball. In some cases, the infection has traveled through the bloodstream to the eye, though this method of infection is less common.

The infection is typically due to bacteria, although fungi or protozoa may also be the cause. Symptoms of endophthalmitis include:

  • severe eye pain
  • redness in the white of the eye
  • sensitivity to bright light
  • decreased vision
  • eyelid swelling

People should seek medical treatment immediately. With endophthalmitis, even immediate treatment is sometimes not enough to stop vision loss. Unfortunately, in some cases, even a delay of just a few hours can lead to irreversible vision loss.

Treatment methods can include antibiotics, corticosteroids, and surgery. During surgery, doctors can remove the infected tissue from the inside of the eye, which may help to stop the infection.

People should make sure to wash their hands regularly. It is important to avoid sharing make-up, contact solutions, eye drops, or anything else that could help spread germs.

Taking care when performing simple activities such as putting on makeup or contacts lenses can help to prevent eye pain. Contact lenses are an easy way to pick up corneal abrasions and infections if people are not careful.

Lenses that have not been cleaned properly and have particles left on them once placed into the eye can scratch the surface. Also, lenses that have been worn too long, left in inappropriately when sleeping, or worn when the eyes are very dry can lead to abrasions.

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Ensuring that hands are clean when touching the area around the eyes may help to stop infections.

Often the abrasions heal without any further complications, but some do develop into infections such as conjunctivitis (pink eye), which can be very contagious.

People should always wear protective eyewear when performing any activity where debris could easily get into the eyes.

Though the cornea is most often affected, problems with other parts of the eye can lead to eye pain and should not be ignored. People should seek help for any eye changes or problems, whether it be pain, redness, or loss of vision.

Many eye problems can be corrected if caught early, but some can lead to irreversible damage or even blindness if they are not treated in time.

Regular eye exams can help to detect any problems that may be present and make sure that the correct diagnosis is made and the appropriate treatment given.