Evaluation of the red eye

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Evaluation of the red eye

Author Deborah S Jacobs, MD
Section Editor Jonathan Trobe, MD
Deputy Editor H Nancy Sokol, MD

Last literature review version 16.2:May 2008
This topic last updated: June 2, 2008 (More)

INTRODUCTION A "red eye" is a common presenting complaint. Some patients with red eyes need urgent ophthalmic referral and treatment, although the vast majority can be treated by the primary care clinician. There are little epidemiologic data on the red eye, nor are there evidence-based data to guide us in the management of these patients. Conjunctivitis (allergic or viral) is probably the most common cause of red eye in the community setting, but a number of more serious conditions can also occur [1,2] .This topic review will present an approach for distinguishing patients with red eye who must be referred to an ophthalmologist, such as those with angle closure glaucoma, from patients who can be managed by the primary care clinician, such as those with allergic conjunctivitis (show table 1 and show table 2). Some distinguishing features of conditions presenting as a red eye are summarized in Table 3 (show table 3). The specific diagnosis and treatment of these disorders are discussed separately. (See "Eyelid lesions", see "Conjunctivitis", and see "Corneal abrasions and corneal foreign bodies").

PATIENT EVALUATION " Measurement of visual acuity and findings on penlight examination are central features in determining management of the red eye. The history and overall patient assessment are useful and confirmatory in the decision to manage or refer.

History
Many patients with a red eye call to inquire whether they need to be seen by a clinician. Certain historical features or presenting complaints signal the need for clinician examination and possibly patient referral. The following questions should be asked in all patients:
• Is vision affected?
• Can you still read ordinary print with the affected eye?

Patients with impaired vision cannot be managed over the phone; they require a clinician examination and may, depending upon the findings, require ophthalmic referral.

• Is there foreign body sensation?
• Does it feel as though there is something in your eye, interfering with your ability to keep your eye open?


A foreign body sensation is the cardinal symptom of an active corneal process. Objective evidence of foreign body sensation, in which the patient is unable to spontaneously open the eye or keep it open, suggests corneal involvement; with the exception of the initial presentation for corneal abrasion or foreign body, such patients warrant emergent or urgent referral to an ophthalmologist.

In comparison, many patients report a "scratchy feeling," "grittiness," or a sensation "like sand in my eyes" with allergy, viral conjunctivitis, or dry eyes. This is subjective foreign body sensation and does not necessarily suggest a corneal problem that requires referral.

• Is there photophobia?
• Are you sensitive to bright light?

Patients with photophobia should always be examined by a clinician. Patients with an active corneal process have objective signs of photophobia as well as objective signs of foreign body sensation. They may present wearing a hat and/or sunglasses, are likely to cover the affected eye with the hand to block out light, or keep the head down and turned away from light fixtures or windows. They may request that the examination room lights be left off while waiting for the provider. Patients with iritis have objective signs of photophobia, but no objective foreign body sensation.

• Was there trauma?
• Have you suffered an injury due to a finger poke, a tool, utensil, or other object? Was there blunt trauma such as a fist or tennis ball?
• Are you a contact lens wearer?


A history of contact lens wear in the setting of discharge and a red eye should increase the suspicion of keratitis [3] . (See "Conjunctivitis").

• Is there discharge, other than tears, that continues throughout the day?

Morning crusting followed by a watery discharge for the remainder of the day is characteristic of many self-limited processes such as allergy, stye or hordeolum, viral conjunctivitis, allergic conjunctivitis, and dry eyes. Patients typically interpret morning crusting as "pus." Bacterial conjunctivitis and bacterial keratitis cause opaque discharge that persists throughout the day and requires specific therapy. Bacterial conjunctivitis, which is typically not associated with a reduction in visual acuity, foreign body sensation, or photophobia, may be treated by the primary care clinician. Bacterial keratitis, on the other hand, which may or may not affect vision but typically causes objective foreign body sensation and photophobia, requires emergent referral.

General observation
General observation of the patient can provide guidance as to whether the problem is likely to be benign and treatable initially by the primary care clinician or if it requires referral. The subjective report of symptoms and threshold to report symptoms varies among individuals. Lid and conjunctival entities do not cause objective foreign body sensation or photophobia. The patient will be sitting in the examination room with both eyes open, unaffected by the ambient lighting. The patient with viral or allergic conjunctivitis may have signs of or complain of rhinorrhea, lymphadenopathy, or other upper respiratory tract symptoms.In comparison, the patient suffering from infectious keratitis, iritis, or angle closure glaucoma is likely to have objective signs indicating the more serious nature of the problem. These entities all require ophthalmologic consultation.

Findings with specific etiologies

Infectious keratitis
Bacterial infectious keratitis warrants evaluation by an ophthalmologist on the same day. The patient will complain of foreign body sensation, and have trouble keeping the involved eye open, a sign of an active corneal process. Overnight wear of contact lenses is associated with a higher incidence of bacterial keratitis, but the entity can occur in patients who do not wear contact lenses or who wear them on a daytime only basis.The diagnostic finding in bacterial keratitis is a corneal opacity or infiltrate (typically a round white spot) in association with red eye, photophobia, and foreign body sensation. This infiltrate or ulcer (>0.5 mm in size) can be seen with a penlight, and does not require a slit lamp for identification. It will stain with fluorescein. Mucopurulent discharge is typically present. Fulminant cases may present with an associated hypopyon (layer of white cells in the anterior chamber).

Herpes simplex causes infectious keratitis, characterized by red eye, photophobia, foreign body sensation, and watery discharge. There may be a faint branching grey opacity on penlight exam. This branching opacity is best visualized with application of fluorescein. Although typically a self-limited process, duration of symptoms is reduced with treatment with topical or oral antiviral agents. (See "Treatment and prevention of herpes simplex virus type 1 infection").Patients should be referred to an ophthalmologist within a few days for confirmation of diagnosis, initiation of therapy, and monitoring for response, sequelae, or recurrence.

Immunocompromised patients may require topical and systemic treatment, and longer duration of therapy. A small percentage of patients develop chronic or recurrent inflammation, or recurrent viral keratitis, both of which are treated with prophylactic oral antiviral agents. Some patients also benefit from treatment with topical corticosteroid agents, used in conjunction with antiviral prophylaxis, under the care of an ophthalmologist.

Adenovirus typically causes conjunctivitis, but some strains in some individuals can cause an associated keratitis (epidemic keratoconjunctivitis or EKC). These patients have classic manifestations of viral conjunctivitis, but within a few days develop symptoms of an active corneal process (photophobia and objective foreign body sensation). Penlight exam of cornea is unremarkable, but fluorescein staining reveals multiple punctate staining lesions. Preauricular lymphadenopathy is often present.

EKC or adenoviral keratitis is typically a self-limited process without sequelae, although patients are quite miserable during active disease because of photophobia and foreign body sensation. Referral to an ophthalmologist within days is warranted for confirmation of the diagnosis, for monitoring for resolution, and for treatment if there is decline in vision from centrally located viral lesions. (See "Diagnosis and treatment of adenovirus infection in adults").

Iritis
Patients with iritis may present in a similar fashion to those with an active corneal process but there is no foreign body sensation per se. The patient may choose to keep the eyes closed to block out light but, in a dimly lit environment, the patient is able to keep the affected eye open spontaneously. Patients with an active corneal process and iritis will display an aversive response when the penlight is shined in the affected and in the uninvolved eye.

The cardinal sign of iritis is ciliary flush: injection that gives the appearance of a red ring around the iris. Typically, there is no discharge and only minimal tearing. Iritis can be caused by any one of many infections, inflammatory, and infiltrative processes. These include tuberculosis, sarcoidosis, syphilis, toxoplasma, toxocara, and Reiter's syndrome. Many cases are idiopathic. Patients with iritis should be seen by an ophthalmologist within a matter of days. The ophthalmologist will initiate treatment, typically with topical steroids, and monitor for side effects and response to therapy. Cases that are bilateral, recurrent, sight-threatening, or non-responsive to therapy will require extensive evaluation for etiology.

Angle closure glaucoma
Acute angle closure glaucoma is relatively uncommon, but the incidence increases dramatically with age [4] . Angle closure leads to increased intraocular pressure (show figure 1A-1B). The patient with angle closure glaucoma typically appears to be in general distress. He or she is likely to be slumped over covering the eye or clutching the frontal or temporal region of the head with one hand, complaining of headache and malaise. As angle closure progresses and the intraocular pressure rises, patients develop nausea and in some cases vomiting. The pain of angle closure is a dull ache that is more likely reported as unilateral headache rather than eye pain. Some patients complain of "the worst headache in my life" and do not attribute their symptoms to the eye. (See "Angle-closure glaucoma"). Unnecessary neurologic workup and imaging that may critically delay treatment can be avoided if the red eye is noted and assessed. Acuity becomes increasingly reduced as the duration of the attack increases. These patients may be photophobic. They do not typically complain of a foreign body sensation. Penlight examination reveals a red eye with ciliary flush and no discharge. The pupil is fixed in mid-dilation and the anterior chamber is shallow. Within hours of symptom onset the cornea becomes hazy.

Diagnosis is confirmed with measurement of intraocular pressure. Normal intraocular pressure is 8 to 22 mm Hg; pressures in acute angle closure are often greater than 45 mm Hg. Angle closure glaucoma is a sight-threatening emergency that must be treated within hours to avoid irreversible damage to the optic nerve. Typically, pressure-lowering topical and systemic agents are administered, and definitive treatment in the form of laser iridotomy is performed that same day by the ophthalmologist. The fellow eye is then treated prophylactically within days.

Subconjunctival hemorrhage
Patients with subconjunctival hemorrhage are generally asymptomatic. Typically the patient is unaware of a problem until he or she looks in the mirror or is informed of it by someone else. The clinical appearance of subconjunctival hemorrhage, with demarcated areas of extravasated blood just beneath the surface of the eye, is generally both obvious and diagnostic. However, the appearance can be quite alarming to patients and their contacts.

Subconjunctival hemorrhage may occur spontaneously or with Valsalva associated with coughing, sneezing, straining, or vomiting. The diagnosis is confirmed by normal acuity, and the absence of discharge, photophobia, or foreign body sensation. The blood pressure should be checked to exclude hypertension; however, there is only poor evidence for such an association. The blood is typically resorbed over 1 to 2 weeks, depending on the amount of extravasated blood. Because the subconjunctival space is loculated, the amount of blood may seem to increase on the second day, but this typically represents redistribution. No specific therapy is indicated.

If subconjunctival hemorrhage is recurrent or if the patient has a history of bleeding disorder, blood dyscrasia, or is on anticoagulant therapy, then an underlying hematologic or coagulation abnormality must be considered. Eyes with subconjunctival hemorrhage in the setting of blunt trauma must be evaluated for the possibility of ruptured globe or retrobulbar hemorrhage.

Ophthalmologic examination Measurement of visual acuity
Vision should be documented for every patient who is seen for an eye complaint. (An inquiry should be made about a change in vision on every telephone triage). Each eye should be tested separately. Snellen acuity is the standard; however, this test requires using a Snellen chart at 20 feet with best correction or pinhole and is often difficult to perform. An alternative in a triage setting is measurement of near vision. Allow the patient to use his or her usual reading correction if possible and hold a near card or ordinary book, newspaper, or magazine at a comfortable distance. It is not important to determine exactly whether the vision is 20/30 or 20/40 at 12 or 14 inches, but rather to document visual acuity in crude categories: reading vision (small print versus large print); form vision only (hand motions or count fingers); or light perception. This measurement should be made before lights are shined in the eye or drops of any sort are applied.

In cases in which a lid disorder, conjunctival process, corneal abrasion, or foreign body is suspected, the presence of normal acuity can be a source of reassurance to the primary care clinician that it is reasonable for them to initiate therapy. On the other hand, if acuity is reduced in the presence of a red eye beyond that which the patient reports is typical, the clinician should suspect one of the more worrisome diagnoses: infectious keratitis, iritis, or angle closure glaucoma. These patients should be referred for initial therapy.

Penlight examination
The penlight should be used to examine the pupils and anterior segment. A slit lamp is not required to distinguish those entities that can be treated by the primary care clinician from those entities that must be referred. It is useful to consider the following questions during the penlight examination:

• Does the pupil react to light?

The pupil is fixed in mid-dilation in cases of angle closure glaucoma. It does not react to light and is typically 4 to 5 mm in diameter.

• Is the pupil very small (1 to 2 mm) in size?

The pupil is pinpoint in cases of corneal abrasion, infectious keratitis, or iritis. Abrasion is distinguished from iritis by the presence of a staining defect on fluorescein examination and an objective foreign body sensation, neither of which is present with iritis. Abrasions are usually caused by focal trauma to the surface of the eye.

Traumatic iritis may occur after blunt trauma, a softball, or a fist, but there are no corneal findings.

• Is there purulent discharge?

Purulent discharge suggests bacterial conjunctivitis or bacterial keratitis. In conjunctivitis, there are no opacities by penlight or staining defects with fluorescein.

• What is the pattern of redness?

Diffuse injection involving both the conjunctiva inside the lid (the palpebral conjunctiva) and the conjunctiva on the globe (the bulbar conjunctiva) suggests a primary conjunctival problem such as conjunctivitis. Conjunctivitis may be bacterial, viral, allergic, toxic, or nonspecific (eg, dry eye syndrome). In these entities the entire mucus membrane is equally involved. In comparison, ciliary flush is characteristic of the more serious entities including infectious keratitis, iritis, or angle closure. With ciliary flush, injection is most marked at the limbus (where the cornea undergoes transition to the sclera) and then diminishes toward the equator. When the redness appears hemorrhagic rather than in a pattern of injection (dilated blood vessels), the diagnosis of subconjunctival hemorrhage should be considered.

• Is there a white spot, opacity or foreign body on the cornea?

A white spot or opacity on the cornea suggests infectious keratitis. This can usually be seen without the aid of fluorescein. Fluorescein is used at the end of the examination to confirm the absence or presence of a corneal process. The white spot of a bacterial keratitis and the raised, grayish branching opacity of herpes simplex keratitis will pick up stain (show picture 1). Abrasions will also pick up stain; however, these are not characterized by the presence of corneal opacity. A corneal foreign body will not pick up stain.

• Is there hypopyon or hyphema?

Hypopyon, a layer of white cells in the anterior chamber, or hyphema, a layer of red cells, each require urgent referral to an ophthalmologist. Hypopyon is associated with sight-threatening infectious keratitis or endophthalmitis until proven otherwise; these patients must be seen by an ophthalmologist within hours.

Hyphema is a sign of significant blunt or penetrating trauma to the globe and must also be seen by an ophthalmologist within hours to evaluate for penetrating eye injury, retinal detachment, and acute glaucoma. (See "Traumatic hyphema: Clinical features and management").

Fundus examination
The fundus examination is typically not helpful in the differential diagnosis of the red eye. In the benign entities such as lid and conjunctival processes, the fundus examination is easily performed and has no associated pathologic features. In iritis and keratitis, the pupil will be very small and the patient photophobic, making the examination difficult to perform. Although the pupil is midsize in angle closure glaucoma, the fundus examination becomes increasingly difficult to perform as the attack persists because of increasing corneal edema from high intraocular pressure.

SUMMARY
If vision is unaffected; the pupil reacts; there is no objective foreign body sensation or photophobia; and there is no corneal opacity, hypopyon, or hyphema, it is reasonable for the primary care clinician to make an initial diagnosis and initiate therapy. The following are indications for emergent (immediate) ophthalmology referral [2]:

Unilateral red eye in a generally uncomfortable patient with nausea and vomiting (suggestive of acute angle-closure glaucoma)
Severe ocular pain or a visual deficit in association with a red eye
Corneal infiltrate or opacity that stains with fluorescein (sometimes called an "ulcer")
Hypopyon

For those entities that require emergent or urgent ophthalmic referral, there is no need for the primary care clinician to initiate therapy unless directed to do so by the consulting ophthalmologist.