Merck Manual

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Some Causes and Features of Eye Redness

Some Causes and Features of Eye Redness

Cause

Common Features*

Diagnostic Approach†

Conjunctival disorders and episcleritis‡

Affecting both eyes

An itching or scratching sensation and tearing

In people with known allergies or other features of allergies (such as a runny nose that recurs during certain seasons)

Sometimes in people who use eye drops (particularly neomycin)

A doctor's examination alone

Chemical (irritant) conjunctivitis

An itching or scratching sensation and tearing

Exposure to potential irritants (such as dust, smoke, ammonia, or chlorine)

A doctor's examination alone

Affecting only one eye

A spot of redness on the white of the eye

Mild irritation of the eye

A doctor's examination alone

An itching or scratching sensation, tearing, and sensitivity to light

Sometimes a discharge from the eye and eyelid swelling

Sometimes swollen lymph nodes in front of the ears

A doctor's examination alone

Affecting only one eye

A red patch or large area of redness (that looks like blood or ketchup)

No tearing, irritation, itching, change in vision, pain, or discharge from the eye

Sometimes in people who have had an eye injury, sneezed violently, or tried to exhale without letting air escape, as may occur during a bowel movement or while lifting a heavy weight (called the Valsalva maneuver)

Often in people known to use drugs that help prevent blood from clotting (such as aspirin or warfarin)

A doctor's examination alone

Corneal disorders§

Eye ache, redness, tearing, and sensitivity to light

In people who have worn their contact lenses for too long

A doctor's examination alone

Symptoms that begin after an eye injury (which may not have been noticed in infants and young children)

Pain when blinking and a foreign body sensation

A doctor's examination alone

Sometimes a grayish patch on the cornea that later becomes an open, painful sore

Sometimes in people who have had an eye injury or who slept with their contact lenses in

A doctor's examination

Culture of a sample taken from the ulcer (done by an ophthalmologist)

Watery discharge

Eyelid swelling, enlarged lymph nodes and bulging of conjunctiva

Sometimes temporary loss of vision

A doctor's examination alone

Affecting only one eye

Early: Blisters on the eyelid and/or crusting

Late or recurring: Eye redness and tearing, eye pain, impaired vision, and sensitivity to light

A doctor's examination

Sometimes, testing for the virus in scrapings obtained from the surface of the cornea or from blisters around the eye

Affecting only one eye

Early: A rash with fluid-filled blisters and/or crusting on one side of the face, around the eye, on the forehead, and/or on the tip of the nose, and sometimes pain

Eye redness, tearing, and eyelid swelling

Late: Eye redness, usually sensitivity to light, and usually severe pain

A doctor's examination

Sometimes, testing for the virus in scrapings obtained from blisters around the eye

Other disorders

Severe eye ache and redness

Headache, nausea, vomiting, and pain with exposure to light

Disturbances in vision such as seeing halos around lights and/or decreased vision

Measurement of pressure inside the eye (tonometry) and examination of the eye's drainage channels with a special lens (gonioscopy), done by an ophthalmologist

Eye ache and sensitivity to light

Eye redness (particularly around the cornea)

Blurring or loss of vision

Often in people who have an autoimmune disorder or who recently had an eye injury

A doctor's examination alone

Pain, often described as boring, and severe enough to wake someone from a sound sleep

Sensitivity to light

Tearing

Red or violet patches on the white of the eye

Often in people who have an autoimmune disorder

A doctor's examination

Sometimes, ultrasound, or CT of the orbits

Rarely, biopsy

* Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present.

† Although a doctor's examination is always done, it is mentioned in this column only if the diagnosis can sometimes be made only by the doctor's examination alone, without any testing. If an ophthalmologist's examination is specifically required, that is mentioned separately.

‡ Conjunctival disorders usually cause itching or a scratchy sensation, tearing, widespread eye redness, and often sensitivity to light. They usually do not cause pain or changes in vision.

§ Corneal disorders usually cause pain (particularly when the eyes are exposed to light), tearing, and sometimes impaired vision.