CHEMICAL OR IRRITATIVE CONJUNCTIVITIS

IATROGENIC CONJUNCTIVITIS FROM TOPICALLY APPLIED DRUGS

A toxic follicular conjunctivitis or an infiltrative, nonspecific conjunctivitis, followed by scarring, is often produced by the prolonged administration of dipivefrin, miotics, idoxuridine, neomycin, and other drugs prepared in toxic or irritating preservatives or vehicles. Silver nitrate instilled into the conjunctival sac at birth (Credé prophylaxis) is a frequent cause of mild chemical conjunctivitis. If tear production is reduced by continual irritation, the conjunctiva can be further damaged by the lack of dilution of the noxious agent as it is instilled into the conjunctival sac.

Conjunctival scrapings often contain keratinized epithelial cells, a few polymorphonuclear neutrophils, and an occasional oddly shaped cell. Treatment consists of stopping the offending agent and using bland drops or none at all. Often the conjunctival reaction persists for weeks or months after its cause has been eliminated.

OCCUPATIONAL CONJUNCTIVITIS FROM CHEMICALS & IRRITANTS

Acids, alkalies, smoke, wind, and almost any irritating substance that enters the conjunctival sac may cause conjunctivitis. Some common irritants are fertilizers, soaps, deodorants, hair sprays, tobacco, makeup preparations (mascara, etc), and various acids and alkalies. In certain areas, smog has become the commonest cause of mild chemical conjunctivitis. The specific irritant in smog has not been positively identified, and treatment is nonspecific. There are no permanent ocular effects, but affected eyes are frequently chronically red and irritated.

In acid burns, the acids denature the tissue proteins and the effect is immediate. Alkalies do not denature the proteins but tend to penetrate the tissues deeply and rapidly and to linger in the conjunctival tissue. Here they continue to inflict damage for hours or days, depending on the molar concentration of the alkali and the amount introduced. Adhesion between the bulbar and palpebral conjunctiva (symblepharon) and corneal leukoma are more likely to occur if the offending agent is an alkali. In either event, pain, injection, photophobia, and blepharospasm are the principal symptoms of caustic burns. A history of the precipitating event can usually be elicited.

Immediate and profuse irrigation of the conjunctival sac with water or saline solution is of importance, and any solid material should be removed mechanically. Do not use chemical antidotes. Further treatment is with intensive topical steroids, ascorbate and citrate eyedrops, cycloplegics, antiglaucoma treatment as necessary, cold compresses, and systemic analgesics (see Chapter 19). Bacterial conjunctivitis may be treated with appropriate antibacterial agents. Corneal scarring may require corneal transplantation, and symblepharon may require a plastic operation on the conjunctiva. Severe conjunctival and corneal burns have a poor prognosis even with surgery, but if proper treatment is started immediately, scarring may be minimized and the prognosis improved.

CATERPILLAR HAIR CONJUNCTIVITIS (OPHTHALMIA NODOSUM)

On rare occasions, caterpillar hairs are introduced into the conjunctival sac, where they produce one or many granulomas (ophthalmia nodosum). Under magnification, each granuloma is seen to contain a small foreign body.

Treatment by removal of each hair individually is effective. If a hair is retained, invasion of the sclera and uveal tract may occur.

10.1036/1535-8860.ch5

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