Red eye (medicine)

A red eye is an eye that appears red due to illness or injury. It is usually injection and prominence of the superficial blood vessels of the conjunctiva, which may be caused by disorders of these or adjacent structures. Conjunctivitis and subconjunctival hemorrhage are two of the less serious but more common causes.

Management includes assessing whether emergency action (including referral) is needed, or whether treatment can be accomplished without additional resources.

Slit lamp examination is invaluable in diagnosis but initial assessment can be performed using a careful history, testing vision (visual acuity), and carrying out a penlight examination.

Diagnosis

Particular signs and symptoms may indicate that the cause is serious and requires immediate attention.

Seven such signs are:

Reduced visual acuity

Ciliary flush (circumcorneal injection)

Corneal abnormalities including edema or opacities ("corneal haze")

Corneal staining

Pupil abormalities including abormal pupil size

Abnormal intraocular pressure

Severe pain

The most useful is a smaller pupil in the red eye than the non-red eye (opposite eye) and sensitivity to bright light.

Reduced visual acuity

A reduction in visual acuity in a 'red eye' is indicative of serious ocular disease, such as keratitis, iridocyclitis, and glaucoma, and never occurs in simple conjunctivitis without accompanying corneal involvement.

Ciliary flush

Ciliary flush is usually present in eyes with corneal inflammation, iridocyclitis or acute glaucoma, though not simple conjunctivitis.

A ciliary flush is a ring of red or violet spreading out from around the cornea of the eye.