Buy the Book PDA Download

Update Me E-mail alerts The Merck Manual Minute

Print This Topic Email This Topic

Eye pain may be described as sharp, aching, or throbbing and should be distinguished from superficial irritation or a foreign body sensation. In some disorders, pain is worsened by bright light. Eye pain may be caused by a serious disorder and requires prompt evaluation. Many causes of eye pain also cause a red eye.

Pathophysiology

The cornea is richly innervated and highly sensitive to pain. Many disorders that affect the cornea or anterior chamber (eg, uveitis) also cause pain via ciliary muscle spasm; when such spasm is present, bright light causes muscle contraction, worsening pain.

Etiology

Disorders that cause eye pain can be divided into those that affect primarily the cornea, other ocular disorders, and disorders that cause pain referred to the eye (see Table 9: Approach to the Ophthalmologic Patient: Some Causes of Eye Pain).

The most common causes overall are

• Corneal abrasion
• Foreign bodies

However, most corneal disorders can cause eye pain.

A feeling of scratchiness or of a foreign body may be caused by either a conjunctival or a corneal disorder.

Table 9
Some Causes of Eye Pain Cause Suggestive Findings* Diagnostic Approach Disorders affecting primarily the cornea† Contact lens keratitis Ocular ache, grittiness, prolonged wearing of contact lenses, bilateral red eyes, lacrimation, corneal edema Clinical evaluation Corneal abrasion or foreign body Usually clear history of injury, unilateral pain when blinking, foreign body sensation Sometimes a predisposing disorder such as trichiasis Lesion or foreign body visible on slit-lamp examination Clinical evaluation, including eyelid eversion Corneal ulcer Aching, foreign body sensation, photophobia, red eye, grayish opacity on cornea—later a visible crater Possibly history of sleeping with contact lenses Scrapings for culture (done by ophthalmologist) Epidemic keratoconjunctivitis (adenoviral keratitis) when severe Ocular ache, grittiness, bilateral red eyes, often eyelid edema, copious watery discharge, preauricular lymphadenopathy, chemosis (bulging of the conjunctiva) Occasionally, severe temporary loss of vision Punctate staining on fluorescein examination Clinical evaluation Herpes zoster ophthalmicus Early: Unilateral vesicles and crusts on an erythematous base in a V1 distribution sometimes affecting the tip of the nose Eyelid edema, red eye Late: Redness, quite severe pain Often associated with uveitis Clinical evaluation Viral culture if diagnosis is unclear Herpes simplex keratitis Acute: Onset after conjunctivitis, blisters on eyelid Late acute or recurrent: Classic dendritic corneal lesion on slit-lamp examination Unilateral Clinical evaluation Viral culture if diagnosis is unclear Welder's or UV keratitis Onset hours after exposure to excessive UV light (eg, from welding or bright sun on snow) Bilateral, ocular ache, grittiness Marked injection and typical punctate staining on fluorescein examination of the cornea Clinical evaluation Other ocular disorders Acute angle-closure glaucoma Severe ocular ache, headache, nausea, vomiting, halos around lights, hazy cornea (caused by edema), marked erythema Intraocular pressure usually > 40 Gonioscopy by ophthalmologist Anterior uveitis Ocular ache, ciliary flush, photophobia, often a risk factor (eg, autoimmune disorder, posttrauma) Cells and flare on slit-lamp examination Rarely, hypopyon Clinical evaluation Endophthalmitis Ocular ache, intense conjunctival hyperemia, photophobia, severely decreased visual acuity, risk factors (usually after intraocular surgery or trauma) Unilateral Cells and flare and commonly hypopyon on slit-lamp examination Clinical evaluation and cultures of aqueous or vitreous humor by ophthalmologist Optic neuritis Mild pain, may worsen with eye movement Vision loss, from small scotoma to blindness Afferent pupillary defect (a particularly characteristic finding if patients have some preservation of visual acuity) Eyelids and cornea normal, sometimes a swollen optic disk Gadolinium-enhanced MRI considered to look for optic nerve edema and demyelinating lesions within the brain (most commonly due to multiple sclerosis) Orbital cellulitis Ocular ache, periocular ache, red and swollen eyelids, proptosis, impaired extraocular movements, decreased visual acuity, fever Unilateral CT or MRI Orbital pseudotumor Ocular ache, periocular ache (may be very severe), unilateral proptosis Impaired extraocular movements, periorbital edema, gradual onset CT or MRI Biopsy Scleritis Pain very severe (often described as boring), photophobia, lacrimation, red or violaceous patches under bulbar conjunctiva, scleral edema, often history of autoimmune disorder Clinical evaluation Disorders causing referred pain Cluster or migraine headaches Prior episodes, characteristic temporal pattern (eg, clusters of episodes at the same time each day) Aura, knife-like quality, throbbing, rhinorrhea, lacrimation, facial flushing, sometimes photosensitivity or photophobia Clinical evaluation Sinusitis Sometimes periorbital edema but eye examination otherwise unremarkable Purulent rhinorrhea, headache, or eye or facial pain that varies with head position Facial tenderness, fever, sometimes productive nocturnal cough, halitosis Sometimes CT *Routine evaluation should include slit-lamp examination with fluorescein staining and ocular tonometry. †Most patients have lacrimation and true photophobia (shining a light into the unaffected eye causes pain in the affected eye when the affected eye is shut). UV = ultraviolet.

Evaluation

History: History of present illness should address the onset, quality, and severity of pain and any history of prior episodes (eg, daily episodes in clusters). Important associated symptoms include the presence of true photophobia (shining a light into the unaffected eye causes pain in the affected eye when the affected eye is shut), decreased visual acuity, foreign body sensation and pain when blinking, and pain when moving the eye.

Review of systems should seek symptoms suggesting a cause, including presence of an aura (migraine); fever and chills (infection); pain when moving the head, purulent rhinorrhea, productive or nocturnal cough, and halitosis (sinusitis).

Past medical history should include known disorders that are risk factors for eye pain, including autoimmune disorders, multiple sclerosis, migraine, and sinus infections. Additional risk factors to assess include use (and overuse) of contact lenses (contact lens keratitis); exposure to excessive sunlight or to welding (UV keratitis); hammering or drilling metal (foreign body); and recent eye injury or surgery (endophthalmitis).

Physical examination: Vital signs are checked for the presence of fever. The nose is inspected for purulent rhinorrhea, and the face is palpated for tenderness. If the eye is red, the preauricular region is checked for adenopathy. Hygiene during examination must be scrupulous when examining patients who have chemosis, preauricular adenopathy, punctate corneal staining, or a combination; these findings suggest epidemic keratoconjunctivitis, which is highly contagious.

Eye examination should be as complete as possible for patients with eye pain. Best corrected visual acuity is checked. Visual fields are typically tested by confrontation in patients with eye pain, but this can be insensitive (particularly for small defects) and unreliable due to poor patient cooperation. A light is moved from one eye to the other to check for pupillary size and direct and consensual pupillary light responses. In patients who have unilateral eye pain, a light is shined in the unaffected eye while the affected eye is shut; pain in the affected eye represents true photophobia. Extraocular movements are checked. The orbital and periorbital structures are inspected. Conjunctival injection that seems most intense and confluent around the cornea and limbus is called ciliary flush.

Slit-lamp examination is done if possible. The cornea is stained with fluorescein and examined under magnification with cobalt-blue light. If a slit lamp is unavailable, the cornea can be examined after fluorescein staining with a Wood's light using magnification. Ophthalmoscopy is done, and ocular pressures are measured (tonometry). In patients with a foreign body sensation or unexplained corneal abrasions, the eyelids are everted and examined for foreign bodies.

Red flags: The following findings are of particular concern:

• Vomiting, halos around lights, or corneal edema
• Signs of systemic infection (eg, fever, chills)
• Decreased visual acuity
• Proptosis
• Impaired extraocular motility

Interpretation of findings: Suggestive findings are listed in Table 9: Approach to the Ophthalmologic Patient: Some Causes of Eye Pain. Some findings suggest categories of disorders.

Scratchiness or a foreign body sensation is most often caused by disorders of the eyelids, conjunctivae, or superficial cornea. Photosensitivity is possible.

Surface pain with photophobia is often accompanied by a foreign body sensation and pain when blinking; it suggests a corneal lesion, most often a foreign body or abrasion.

Deeper pain—often described as aching or throbbing—usually indicates a serious disorder such as glaucoma, uveitis, scleritis, endophthalmitis, orbital cellulitis, or orbital pseudotumor. Within this group, eyelid swelling, proptosis, or both and impaired extraocular movements or visual acuity suggest orbital pseudotumor, orbital cellulitis, or possibly severe endophthalmitis. Fever, chills, and tenderness suggest infection (eg, orbital cellulitis, sinusitis).

A red eye suggests that the disorder causing pain is ocular rather than referred.

If pain develops in the affected eye in response to light exposure to the unaffected eye when the affected eye is shut (true photophobia), the cause is most often a corneal lesion or uveitis.

If topical anesthetic drops (eg, proparacaine Some Trade Names
ALCAINE
OPHTHETIC
Click for Drug Monograph
) abolish pain in a red eye, the cause is probably a corneal disorder.

Some findings are more suggestive of particular disorders. Pain and photophobia days after sustaining blunt eye trauma suggest uveitis. Hammering or drilling metal is a risk factor for occult metal intraocular foreign body. Pain with movement of extraocular muscles and loss of pupillary light response that is disproportionate to loss of visual acuity suggest optic neuritis.

Testing: Testing is not usually necessary, with some exceptions (see Table 9: Approach to the Ophthalmologic Patient: Some Causes of Eye Pain). Gonioscopy is done if glaucoma is suspected by increased intraocular pressure. Imaging, usually with CT or MRI, is done for suspected orbital pseudotumor or orbital cellulitis, or if sinusitis is suspected but the diagnosis is not clinically clear. MRI is often done when optic neuritis is suspected, looking for demyelinating lesions in the brain suggestive of multiple sclerosis.

Intraocular fluids (vitreous and aqueous humor) may be cultured for suspected endophthalmitis. Viral cultures can be used to confirm herpes zoster ophthalmicus or herpes simplex keratitis if the diagnosis is not clear clinically.

Treatment

The cause of pain is treated. Pain itself is also treated. Systemic analgesics are used as needed. Pain caused by uveitis and many corneal lesions also is relieved with cycloplegic eye drops (eg, homatropine Some Trade Names
ISOPTO
Click for Drug Monograph
5% qid).

Key Points

• Most diagnoses can be made by clinical evaluation.
• Infection precautions should be maintained when examining patients with bilateral red eyes.
• Important danger signs are vomiting, halos around lights, fever, decreased visual acuity, proptosis, and impaired extraocular motility.
• Pain in the affected eye in response to shining light in the unaffected eye when the affected eye is shut (true photophobia) suggests a corneal lesion or uveitis.
• If pain resolves with a topical anesthetic (eg, proparacaine Some Trade Names
  ALCAINE
  OPHTHETIC
  Click for Drug Monograph
  ), the cause of pain is a corneal lesion.
• Hammering or drilling on metal is a risk factor for occult intraocular foreign body.

Last full review/revision April 2009 by Kathryn Colby, MD, PhD

Content last modified April 2009