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Red Eye

(Pink Eye)

By

Christopher J. Brady

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

Last full review/revision May 2021| Content last modified May 2021
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Red eye refers to a red appearance of the opened eye, reflecting dilation of the superficial ocular vessels.

Pathophysiology of Red Eye

Dilation of superficial ocular vessels can result from

  • Infection

  • Allergy

  • Inflammation (noninfectious)

  • Elevated intraocular pressure (less common)

Several ocular components may be involved, most commonly the conjunctiva, but also the uveal tract, episclera, and sclera.

Etiology of Red Eye

Evaluation of Red Eye

Most disorders can be diagnosed by a general health care practitioner.

History

History of present illness should note the onset and duration of redness and presence of any change in vision, itching, scratchy sensation, pain, or discharge. Nature and severity of pain, including whether pain is worsened by light (photophobia), are noted. The clinician should determine whether discharge is watery or purulent. Other questions assess history of injury, including exposure to irritants and use of contact lenses (eg, possible overuse, such as wearing them while sleeping). Prior episodes of eye pain or redness and their time patterns are elicited.

Review of systems should seek symptoms suggesting possible causes, including headache, nausea, vomiting, and halos around lights (acute angle-closure glaucoma Angle-Closure Glaucoma Angle-closure glaucoma is glaucoma associated with a physically obstructed anterior chamber angle, which may be chronic or, rarely, acute. Symptoms of acute angle closure are severe ocular pain... read more ); runny nose and sneezing (allergies, upper respiratory infection); and cough, sore throat, and malaise (upper respiratory infection).

Past medical history includes questions about known allergies and autoimmune disorders. Drug history should specifically ask about recent use of topical ophthalmic drugs (including over-the-counter drugs), which might be sensitizing.

Physical examination

General examination should include head and neck examination for signs of associated disorders (eg, upper respiratory infection, allergic rhinitis, zoster rash).

Eye examination involves a formal measure of visual acuity and usually requires a penlight, fluorescein stain, and slit lamp.

Best corrected visual acuity is measured. Pupillary size and reactivity to light are assessed. True photophobia (sometimes called consensual photophobia) is present if shining light into an unaffected eye causes pain in the affected eye when the affected eye is shut. Extraocular movements are assessed, and the eye and periorbital tissues are inspected for lesions and swelling. The tarsal surface is inspected for papillae. The corneas are stained with fluorescein and examined with magnification. If a corneal abrasion is found, the eyelid is everted and examined for hidden foreign bodies. Inspection of the ocular structures and cornea is best done using a slit lamp. A slit lamp is also used to examine the anterior chamber for cells, flare, and pus (hypopyon). Ocular pressure is measured using tonometry, although it may be permissible to omit this test if there are no symptoms or signs suggesting a disorder other than conjunctivitis.

Red flags

The following findings are of particular concern:

  • Sudden, severe pain and vomiting

  • Zoster rash

  • Decreased visual acuity

  • Corneal crater

  • Branching, dendritic corneal lesion

  • Ocular pressure > 40 mm Hg

  • Failure to blanch with phenylephrine eye drop

Interpretation of findings

Conjunctival disorders and episcleritis are differentiated from other causes of red eye by the absence of pain, photophobia, and corneal staining. Among these disorders, episcleritis Episcleritis Episcleritis is self-limiting, recurring, usually idiopathic inflammation of the episcleral tissue that does not threaten vision. Symptoms are a localized area of hyperemia of the globe, irritation... read more Episcleritis is differentiated by its focality, and subconjunctival hemorrhage is usually differentiated by the absence of lacrimation, itching, and photosensitivity. Clinical criteria do not accurately differentiate viral from bacterial conjunctivitis.

Corneal disorders are differentiated from other causes of red eye (and usually from each other) by fluorescein staining. These disorders also tend to be characterized by pain and photophobia. If instillation of an ocular anesthetic drop (eg, proparacaine 0.5%), which is done before tonometry and ideally before fluorescein instillation, completely relieves pain, the cause is probably limited to the cornea. If pain is present and is not relieved by an ocular anesthetic, the cause may be anterior uveitis Overview of Uveitis Uveitis is defined as inflammation of the uveal tract—the iris, ciliary body, and choroid. However, the retina and fluid within the anterior chamber and vitreous are often involved as well.... read more Overview of Uveitis , glaucoma Overview of Glaucoma Glaucomas are a group of eye disorders characterized by progressive optic nerve damage in which an important part is a relative increase in intraocular pressure (IOP) that can lead to irreversible... read more , or scleritis Scleritis Scleritis is a severe, destructive, vision-threatening inflammation involving the deep episclera and sclera. Symptoms are moderate to marked pain, hyperemia of the globe, lacrimation, and photophobia... read more Scleritis . Because patients may have anterior uveitis secondary to corneal lesions, persistence of pain after instillation of the anesthetic does not exclude a corneal lesion.

Anterior uveitis, acute angle-closure glaucoma, and scleritis can usually be differentiated from other causes of red eye by the presence of pain and the absence of corneal staining. Anterior uveitis is likely in patients with pain, true photophobia, absence of corneal fluorescein staining, and normal intraocular pressure; it is definitively diagnosed based on the presence of cells and flare in the anterior chamber. However, these findings may be difficult for general health care practitioners to discern. Acute angle-closure glaucoma can usually be recognized by the sudden onset of its severe and characteristic symptoms, but tonometry is definitive.

Pearls & Pitfalls

  • If pain persists despite an ocular anesthetic in a patient with a normal fluorescein examination, consider anterior uveitis, scleritis, or acute angle-closure glaucoma.

Instillation of phenylephrine 2.5% causes blanching in a red eye unless the cause is scleritis Scleritis Scleritis is a severe, destructive, vision-threatening inflammation involving the deep episclera and sclera. Symptoms are moderate to marked pain, hyperemia of the globe, lacrimation, and photophobia... read more Scleritis . Phenylephrine is instilled to dilate the pupil in patients needing a thorough retinal examination. However, it should not be used in patients who have the following:

Testing

Testing is usually unnecessary. Viral cultures may help if herpes simplex Herpes Simplex Virus (HSV) Infections Herpes simplex viruses (human herpesviruses types 1 and 2) commonly cause recurrent infection affecting the skin, mouth, lips, eyes, and genitals. Common severe infections include encephalitis... read more Herpes Simplex Virus (HSV) Infections or herpes zoster Herpes Zoster Herpes zoster is infection that results when varicella-zoster virus reactivates from its latent state in a posterior dorsal root ganglion. Symptoms usually begin with pain along the affected... read more Herpes Zoster is suspected and the diagnosis is not clear clinically. Corneal ulcers Corneal Ulcer A corneal ulcer is a corneal epithelial defect with underlying inflammation usually due to invasion by bacteria, fungi, viruses, or Acanthamoeba. It can be initiated by mechanical trauma or... read more Corneal Ulcer are cultured by an ophthalmologist. Gonioscopy is done in patients with glaucoma. Testing for autoimmune disorders may be worthwhile in patients with uveitis Overview of Uveitis Uveitis is defined as inflammation of the uveal tract—the iris, ciliary body, and choroid. However, the retina and fluid within the anterior chamber and vitreous are often involved as well.... read more Overview of Uveitis and no obvious cause (eg, trauma). Patients with scleritis Scleritis Scleritis is a severe, destructive, vision-threatening inflammation involving the deep episclera and sclera. Symptoms are moderate to marked pain, hyperemia of the globe, lacrimation, and photophobia... read more Scleritis undergo further testing as directed by an ophthalmologist.

Treatment of Red Eye

The cause is treated. Red eye itself does not require treatment. Topical vasoconstrictors are not recommended.

Key Points

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