Evaluation of Eye Pain

Claudia U. Richter

Pain in the eye is most often produced by conditions that do not threaten vision, but discomfort may also result from corneal or intraocular pathology that is capable of compromising eyesight. The first responsibility of the primary physician is to determine promptly whether there is an immediate threat to vision that requires urgent therapy or quick referral to the ophthalmologist; minor problems can be treated symptomatically in the office. Pain referable to the orbit from a nonocular etiology may simulate that due to eye pathology and needs to be differentiated. Ocular pain is usually not the only presentation of eye injury or disease; redness (see Chapter 199) and impaired vision (see Chapter 200) may also ensue. Etiologic diagnosis requires taking the entire presentation into consideration.

PATHOPHYSIOLOGY AND CLINICAL PRESENTATION (1, 2 and 3)

The external ocular surfaces (lid, conjunctiva, and cornea) and the uveal tract are richly innervated to detect pain. Localization within these structures is relatively less precise because most pain localizes to the upper outer lid regardless of the location of the surface lesion. The orbit and sinuses may give rise to pain localized to the eye. Pathology confined to the vitreous, retina, or optic nerve is rarely a source of pain.

Eyelids

Inflammation of the eyelid causes tenderness and foreign-body sensation. Common causes are hordeolum (stye), chalazion, trichiasis (inturned lashes), tarsal foreign bodies, cellulitis, and herpes infection. Redness and edema may accompany the pain.

Conjunctiva

Viral and bacterial conjunctivitis cause mild burning and foreign-body sensation, whereas allergic conjunctivitis primarily elicits itching (see Chapter 199). Toxic, chemical, and mechanical injuries are commonly responsible for unilateral disease with a myriad of symptoms.

Cornea

The cornea is densely innervated by pain fibers, so even a minor injury may result in considerable discomfort. Pain arises from exposure of nerve endings in the epithelium; the patient complains of a burning or foreign-body sensation and, in some cases, reflex photophobia and tearing. Blinking exacerbates the pain. Ocular surface disease from dry eye can produce discomfort (see Chapter 202).

Keratitis (inflammation of the cornea) occurs with trauma, infection, exposure, vascular disease, or decreased lacrimation. Contact lens use is an important source of microbial keratitis. Severe pain is a prominent symptom; movement of the lid typically exacerbates symptoms. Decreased vision may result from irregularities of the surface of the cornea, inflammation in the corneal stroma, and neovascularization of the normally avascular stroma. Fluorescein stain reveals the epithelial defects quite well and allows identification with a penlight. In infectious keratitis, corneal infiltrates are sometimes visible with a penlight, appearing as white spots.

Sclera

Compared with disease of the eyelids, scleral problems are more likely to cause dull, deep pain. If the condition involves the anterior sclera, it may be readily visible as an area of redness. Tenderness on palpation of the inflamed area may be present and, rarely, pain with eye movement. Posterior scleritis may present with vision loss.

Uveal Tract

Anterior uveitis or iritis is accompanied by a dull ache and photophobia due to the irritative spasm of the ciliary body and pupillary sphincter. Posterior uveitis without anterior involvement may be painless or cause deep-seated aching.

In acute angle-closure glaucoma and other acute glaucomas, profound ocular and orbital pain radiating to the frontal and temporal regions accompany sudden elevation of intraocular pressure; vagal stimulation from the high pressure may result in nausea and vomiting. Often with angle-closure glaucoma, the patient gives a history of mild intermittent episodes of blurred vision with colored haloes around lights preceding the onset of an attack of throbbing pain, nausea, vomiting, and decreased visual acuity. A fixed midposition pupil, redness, and a hazy cornea may be present (see Chapter 207).

Orbit

Inflammation and rapidly expanding mass lesions may cause deep pain in the orbit. Displacement of the globe and diplopia may ensue, as seen in cases of Graves ophthalmopathy, orbital infections, and orbital tumors. In orbital cellulitis, there is proptosis, limitation of extraocular movement, injection, and diminished vision. Orbital pseudotumor often presents in a very similar fashion to orbital cellulitis. Sinusitis may also cause secondary orbital inflammation and tenderness on extremes of eye movement.

Optic neuritis, a condition of younger patients (aged 15 to 40 years), is frequently associated with multiple sclerosis. Onset is sudden, and symptoms include pain on eye movement due to meningeal inflammation at the orbital apex origin of the extraocular muscles. Abnormal color vision and variable loss of central vision occur. In most instances, the optic disk appears normal, but occasionally there is edema.

Other Sources

Mild headache referred to the orbit is associated with refractive error, ocular muscle imbalance, sinusitis, and other causes of nonocular headache, such as tension headache, cluster headache, migraine, temporal arteritis, and the prodromal phase of herpes zoster. Severe aches in the eye cannot be attributed to refractive error, nor can aches about the eye that are noted on awakening in the morning. Trigeminal neuralgia may present with sharp stabbing pains of brief duration localized to the eye.

TABLE 201-1 Important Causes of Eye Pain

Extraocular Causes
	Lid
		Hordeolum (a small abscess of the lid)
		Acute dacryocystitis
		Cellulitis, preseptal or orbital
		Chalazion
		Herpes zoster
	Conjunctival
		Irritant exposure (prolonged sun exposure, pollution, occupational irritants, aerosol propellants, wind, dust)
		Infection (viral or bacterial)
		Lack of sleep
		Dry eyes
	Corneal
		Abrasions
		Foreign bodies
		Ulcers
		Misdirected lashes
		Contact lens injury
	Excessive exposure to sun or other forms of ultraviolet radiation
		Infection (bacterial or viral or fungal)
	Scleral
		Episcleritis
		Scleritis (connective tissue disease)
Intraocular Conditions
	Anterior eye
		Acute angle-closure glaucoma
		Acute anterior uveitis (idiopathic, connective tissue\autoimmune disease, sarcoidosis, inflammatory bowel disease)
		Refractive error (mild pain only)
	Posterior eye
		Posterior uveitis
Orbital Disease
	Tumor
	Inflammatory disease
	Graves ophthalmopathy
	Pseudotumor oculi
	Retrobulbar optic neuritis
	Orbital cellulitis
Referred Pain from Extraocular Sources
	Sinusitis
	Tooth abscess
	Tension, migraine, or cluster headache
	Temporal arteritis
	Prodrome of herpes zoster
	Ocular muscle imbalance
	Trigeminal neuralgia
Other
	Trauma