Conjunctivitis is the most common cause of a red eye. Discharge with crusted eyelids stuck together in the morning, conjunctival erythema (especially of the peripheral bulbar segment), normal vision, lids, and absence of photophobia are the major manifestations. The etiology may be infectious, allergic, or chemical.

Bacterial conjunctivitis is characterized by a mucopurulent discharge and usually occurs unilaterally without preauricular adenopathy. The eyelids have a thick crust on them after a night’s sleep. Streptococcus pneumoniae, Staphylococcus aureus, and Haemophilus influenzae are the most common etiologic pathogens. A severe, hyperacute conjunctivitis suggests Neisseria infection, which may scar or perforate the cornea, leading to systemic dissemination. Chronic conjunctivitis is often due to Staphylococcus aureus or Moraxella lacunata. Chlamydial conjunctivitis, transmitted from the genitourinary tract, occurs as bilateral inclusion conjunctivitis in sexually active young adults, differing in presentation from typical bacterial conjunctivitis by a prominent follicular conjunctival response and preauricular adenopathy. Trachoma is a major cause of blindness and affects approximately 400 million individuals worldwide but is rare in the United States, except among Native Americans in the Southwest. However, the rapidly increasing rate of chlamydial cervicitis (see Chapter 115) among young women raises the risk of trachoma in a much wider population of newborns.

Viral conjunctivitis is characterized by watery, sometimes nonpurulent mucoid discharge, often beginning in one eye and spreading to the other eye several days later. Preauricular adenopathy is common. It may be associated with fever and pharyngitis (pharyngoconjunctival fever), particularly in children. Epidemic keratoconjunctivitis is a highly contagious adenoviral infection that may be accompanied by corneal epithelial defects in the first week and subepithelial infiltrates in the second week, sometimes causing a diminution of vision. Pseudomembranes or scarring of the conjunctiva may occur and sometimes is painful.

Allergic conjunctivitis may be associated with seasonal allergies and atopic dermatitis and is characterized by bilateral itching and tearing. Vernal keratoconjunctivitis is a chronic recurrent hypersensitivity reaction that may lead to the formation of corneal ulcers.

Bilateral sterile conjunctival inflammation can occur in patients with acne rosacea, Reiter syndrome, and Stevens-Johnson syndrome. Patients with acne rosacea may have associated lid inflammation (blepharitis) and develop concomitant sterile marginal corneal ulcers with chronic staphylococcal infection.

Sensitivity to eye medications may cause erythema of the external lids, especially at the lateral canthus with an associated conjunctivitis. Angioneurotic edema of the lids may occur bilaterally as an allergic response to a systemic allergen—often food—or unilaterally secondary to exposure to local allergens such as topical chemicals, poison ivy, and insect bites; it develops rapidly and resolves in 1 to 2 days. Edema without erythema suggests allergy, not infection.

Pinguecula is a yellow-white, harmless nodule of the scleral conjunctiva, usually found on the nasal side and causing mild discoloration; calcific changes may be present. The condition results from heavy exposure to ultraviolet light (actinic exposure). A more problematic consequence of ultraviolet light exposure is a pterygium, which is characterized by wingshaped, fibrovascular conjunctival tissue growth and redness potentially encroaching on the cornea, with the risk of impairing vision.

Subconjunctival hemorrhages are associated with minor trauma. In many instances, the trauma is unapparent and seemingly without provocation. More pronounced hemorrhage usually occurs secondary to obvious trauma. Massive hemorrhage leading to proptosis and limited extraocular movements signals orbital hemorrhage, which may compromise the optic nerve and retinal circulation. Subconjunctival hemorrhages may also appear during an acute conjunctivitis. Systemic causes include impaired clotting and venous congestion (Valsalva maneuver). Clinical findings include a focal or diffuse patch of redness on the conjunctiva, without associated discharge or itching.

A foreign body on the bulbar conjunctiva or under either the upper or lower lid may result in copious tearing, conjunctival injection, and a sensation that something has gotten “into” the eye. On occasion, the foreign body may be well tolerated, with the eye remaining white and quiet.

This is usually a benign inflammation of superficial episcleral vessels, but in recurrent cases (associated with connective tissue disease, gout, herpes, syphilis, tuberculosis, and rosacea), the conjunctiva may manifest areas of circumscribed nodular inflammation, and the patient complains of a mildly tender, red eye. Vision and lids are normal, the corneas are clear, and the conjunctivae show local raised areas of redness.

Scleritis—a potentially destructive, severely painful inflammation of the collagen in the sclera and deep episcleral vessels—is a rare condition associated with autoimmune connective tissue diseases, vasculitides, infectious disorders, and metabolic disorders. An experienced observer is required to make the diagnosis.

Uveitis refers to inflammation of the uveal tract, including the iris, ciliary body, and choroid. Iritis (anterior uveitis) presents with eye pain, photophobia, redness, and pupillary contraction, ciliary flush, and decreased vision. It may be unilateral or bilateral; if it is unilateral, the affected pupil is smaller than that of the other eye because of iris spasm or synechiae. Flashlight examination shows a slightly cloudy anterior chamber. Slit-lamp examination discloses cells in the anterior chamber (aqueous cellular reaction) and “flare” (increased vascular permeability. Inflammatory cells, called “keratic precipitates,” may collect in clusters on the posterior cornea.

Iritis and uveitis are usually idiopathic but may be associated with a large number of systemic and ocular diseases, including ankylosing spondylitis, Behçet syndrome, sarcoidosis, and juvenile rheumatoid arthritis. Infectious and neoplastic diseases are other causes accompanied by posterior segment involvement (posterior uveitis). Ocular trauma can result in reactive iritis.

Blepharitis results from inflammation (both infectious and noninfectious) of the structures of the lid margin and presents as lid-margin redness, scaling, and crusting. Staphylococcal blepharitis produces dry scales, lash loss, and sometimes conjunctivitis and corneal limbal infiltrates. Seborrheic blepharitis and meibomian gland dysfunction are associated with chronic oily secretions causing irritation and dilated vessels at the posterior lid margin in association with conjunctiva inflammation; examination of the margin may reveal inspissated sebaceous material. Meibomian gland dysfunction is frequently associated with seborrheic dermatitis and acne rosacea. Blepharitis tends to be chronic with acute flare-ups and is
more common in fair-skinned people. Table 199-1 lists other causes of eyelid inflammation.

Hordeolum is an acute inflammatory or infectious nodule of the meibomian glands (internal hordeolum), the glands of Zeis, or lash follicles (external hordeolum or sty). It presents as a red, tender mass near the eyelid margin. An internal hordeolum may point to either the skin or the conjunctival side of the lid, whereas an external hordeolum always points to the skin. Hordeolum may produce a diffuse superficial lid infection known as “preseptal cellulitis.”

Chalazion is a sterile chronic granulomatous inflammation of a Zeis or meibomian gland, which may be tender and mildly inflamed or a quiet discrete mass.