Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Eye Pain


Christopher J. Brady

, MD, Wilmer Eye Institute, Retina Division, Johns Hopkins University School of Medicine

Reviewed/Revised Dec 2023
Topic Resources

The cornea (the clear layer in front of the iris and pupil) is highly sensitive to pain. Many disorders that affect the cornea also affect the anterior chamber (the fluid-filled space between the iris and the inner part of the cornea) and cause spasm of the muscle that controls the iris (the ciliary muscle). When such spasm is present, bright light causes muscle contraction and worsening pain.

An Inside Look at the Eye

An Inside Look at the Eye

Causes of Eye Pain

Disorders that cause eye pain can be divided into disorders that affect primarily the cornea, disorders of other parts of the eye, and disorders of other areas of the body that cause pain to be felt in the eye.

Common causes

However, most corneal disorders can cause eye pain.

A feeling of scratchiness or a foreign body sensation may be caused by a disorder of the conjunctiva (the thin membrane that lines the eyelid and covers the front of the eye) or of the cornea.


Evaluation of Eye Pain

Mild eye irritation or a foreign body sensation is common and not usually serious. However, true pain in the eye can be a sign of a severe, vision-threatening disorder. The following information can help people decide when to see a doctor and help them know what to expect during the evaluation.

Warning signs

In people with eye pain, certain symptoms and characteristics are cause for concern. They include

When to see a doctor

People who have severe pain, eye redness, or warning signs should see a doctor right away. People with mild pain and no eye redness or warning signs can wait a day or two to see if the discomfort goes away on its own.

What the doctor does

Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the eye pain and the tests that may need to be done (see table ).

Doctors ask the person to describe the pain, including when it started, how severe it is, and whether it hurts to look in different directions or blink. They ask about whether the person has ever had eye pain and whether the person is sensitive to light, has blurred vision, or feels as if the eye contains a foreign object.

During the physical examination, doctors check for the presence of fever or a runny nose. They check the face for tenderness.

Most important is the eye examination, including the entire eye, eyelids, and the region around the eye. Doctors check

If doctors suspect a foreign object but do not see one, they turn the eyelids inside out to search for hidden foreign objects.

Doctors usually do a slit-lamp examination What Is a Slit Lamp? What Is a Slit Lamp? . A slit lamp is an instrument that enables a doctor to examine the eye under high magnification. Doctors place a drop of fluorescein stain on the cornea to show scratches or certain kinds of infection, including ulcers. Doctors use tonometry Tonometry A person who has eye symptoms should be checked by a doctor. However, some eye disorders cause few or no symptoms in their early stages, so the eyes should be checked regularly (every 1 to 2... read more to measure the pressure inside the eye (intraocular pressure). They use a slit-lamp and/or an ophthalmoscope Ophthalmoscopy A person who has eye symptoms should be checked by a doctor. However, some eye disorders cause few or no symptoms in their early stages, so the eyes should be checked regularly (every 1 to 2... read more (a light with magnifying lenses that shines into the back of the eye) to examine the lens and use an ophthalmoscope to examine the vitreous humor (the jellylike substance that fills the eyeball), retina (the light-sensing structure at the back of the eye), optic nerve, and the retinal veins and arteries.

Sometimes findings are helpful in making a diagnosis. Particular findings or combinations may point to particular disorders.

Findings may also help suggest or eliminate certain types of disorders.


The need for tests depends on what doctors find during the history and physical examination. Testing is usually not necessary. However, if doctors find increased intraocular pressure (indicating glaucoma Glaucoma Glaucomas are a group of eye disorders characterized by progressive optic nerve damage (often, but not always, associated with increased eye pressure) that can lead to irreversible loss of vision... read more ), they may refer the person to an ophthalmologist (a medical doctor who specializes in the evaluation and treatment—surgical and nonsurgical—of eye disorders) for gonioscopy. A gonioscope is a special lens that allows doctors to examine the drainage channels in the eye, which can help determine whether the glaucoma is of the open-angle or closed-angle type.

Treatment of Eye Pain

The best way to treat eye pain is to treat the cause of the pain. People may also need to take pain relievers (such as acetaminophen or a nonsteroidal anti-inflammatory drug) until the pain stops. Sometimes people with pain caused by anterior uveitis Uveitis Uveitis is inflammation anywhere in the pigmented inside lining of the eye, known as the uvea or uveal tract. The uveal tract may become inflamed because of infection, injury, a bodywide autoimmune... read more or corneal disorders Introduction to Corneal Disorders The cornea is the clear layer in front of the iris and pupil. It protects the iris and lens and helps focus light on the retina. It is composed of cells, protein, and fluid. The cornea looks... read more also need to use an eye drop that prevents ciliary muscle spasm by dilating the pupil and thus reduces eye pain with light exposure. For example, cyclopentolate may be used.

Key Points

  • Usually doctors can determine the cause of eye pain during an examination.

  • People with severe pain, eye redness, or warning signs (vomiting, halos around lights, fever, decreased visual clarity, bulging eyes, and inability to move the eye in all directions) should see a doctor right away.

Drugs Mentioned In This Article

Generic Name Select Brand Names
AK-Fluor, Bio Glo, Fluorescite, Fluorets , Fluor-I-Strip, Fluor-I-Strip A.T., Ful-Glo, Ophthalmicflur
7T Gummy ES, Acephen, Aceta, Actamin, Adult Pain Relief, Anacin Aspirin Free, Aphen, Apra, Children's Acetaminophen, Children's Pain & Fever , Children's Pain Relief, Comtrex Sore Throat Relief, ED-APAP, ElixSure Fever/Pain, Feverall, Genapap, Genebs, Goody's Back & Body Pain, Infantaire, Infants' Acetaminophen, LIQUID PAIN RELIEF, Little Fevers, Little Remedies Infant Fever + Pain Reliever, Mapap, Mapap Arthritis Pain, Mapap Infants, Mapap Junior, M-PAP, Nortemp, Ofirmev, Pain & Fever , Pain and Fever , PAIN RELIEF , PAIN RELIEF Extra Strength, Panadol, PediaCare Children's Fever Reducer/Pain Reliever, PediaCare Children's Smooth Metls Fever Reducer/Pain Reliever, PediaCare Infant's Fever Reducer/Pain Reliever, Pediaphen, PHARBETOL, Plus PHARMA, Q-Pap, Q-Pap Extra Strength, Silapap, Triaminic Fever Reducer and Pain Reliever, Triaminic Infant Fever Reducer and Pain Reliever, Tylenol, Tylenol 8 Hour, Tylenol 8 Hour Arthritis Pain, Tylenol 8 Hour Muscle Aches & Pain, Tylenol Arthritis Pain, Tylenol Children's, Tylenol Children's Pain+Fever, Tylenol CrushableTablet, Tylenol Extra Strength, Tylenol Infants', Tylenol Infants Pain + Fever, Tylenol Junior Strength, Tylenol Pain + Fever, Tylenol Regular Strength, Tylenol Sore Throat, XS No Aspirin, XS Pain Reliever
AK-Pentolate , Cyclogyl, Cylate, Ocu-Pentolate
quiz link

Test your knowledge

Take a Quiz!