Chemical Trauma

CHEMICAL OCULAR INJURY A chemical injury to the eye is a true ocular emergency. The potential for chemical injury requires immediate recognition and treatment in the field and by the triage nurse. Immediate intervention consists of copious irrigation with at least 1 to 2 L of saline. Topical anesthesia and placement of a Morgan lens allows the irrigation to be delivered effectively and directly to the corneal surface. This is one situation where a delay even to assess visual acuity is inappropriate. Litmus paper or the pH portion of a urine dipstick can be used to assess the pH of the tears in the lower cul-de-sac. Irrigation should continue until pH testing improves to the range of 6 to 8. Both acid and alkali burns can be blinding; however, the majority of acid burns tend to coagulate proteins, thereby limiting the depth of penetration. Alkali burns (lye, ammonia) can rapidly penetrate the cornea, and aqueous pH can rise within minutes of exposure, causing damage to intraocular structures such as the iris and lens. After copious irrigation has been administered and the pH of the tears is close to normal, the eye should be inspected for any particulate matter and visual acuity should be assessed. A topical cycloplegic agent such as 0.25% scopolamine or 1% cyclopentolate should be used tid for pain reduction if an epithelial defect is present. Erythromycin ophthalmic ointment should be instilled qid if both eyes are affected. If only one eye is affected and an epithelial defect is present, adding a pressure patch for the first 12 to 24 h will sometimes make the eye more comfortable. Any patient with corneal clouding or epithelial defect after irrigation should receive prompt ophthalmology referral.

Patients with chemosis (edema of the bulbar conjunctiva overlying the white sclera) and no corneal or anterior chamber findings should be treated after irrigation with erythromycin ointment qid and referred for an ophthalmologic exam in the next 48 h. These patients are considered to have "chemical conjunctivitis."

Treatment:

1. Immediate copious irrigation with a minimum of 1 to 2 L of saline or until tear pH is 6 to 8.

2. If there is no corneal epithelial defect and the anterior segment is normal, administer erythromycin ointment qid.

3. If there is a corneal epithelial defect or there is clouding, administer erythromycin ointment, cycloplegia (cyclopentolate 1% or scopolamine 0.25%), and optional eye patching. Provide for ophthalmology referral within 24 h.

CYANOACRYLATE ("SUPER GLUE/CRAZY GLUE") Cyanoacrylate adhesives are commonplace and often easily accessible to children. Accidental instillation into the eye and adnexa can cause the lids to adhere and adhesive clumps to form on the cornea. Most of the time these accidental instillations are not permanently harmful to the eye. Medicinal-grade cyanoacrylates are used occasionally directly on the cornea to seal corneal perforations and are not considered toxic to the cornea. The only concern is the mechanical abrasive effect of hard, irregular glue aggregates rubbing against the cornea with eye movement and blinking. Erythromycin is instilled heavily into the eye and on the surface of the eyelids to moisten, lubricate, and provide antibiotic coverage. Initial debridement of the surface glue clump should be limited to easily removable pieces. The glue will loosen and become easier to remove in a few days. Referral to an ophthalmologist should take place within 24 to 48 h.

Treatment:

1. Moisten glue with erythromycin ointment and remove as much as can be removed easily without causing damage to underlying tissue.

2. Apply erythromycin ointment heavily into eye (if not glued completely shut) and eyelids five or six times a day.

3. Refer to ophthalmologist in next 24 to 48 h.

ULTRAVIOLET KERATITIS ("WELDER'S FLASH") Pain, tearing, photophobia, and foreign-body sensation typically occur 6 to 12 h after unprotected ocular exposure to welding or sun-tanning lights. The history is diagnostic in these cases. Slit-lamp examination with fluorescein staining shows superficial punctate keratitis (SPK); this appears as numerous small microdots of staining on the corneal surface seen under high magnification using the cobalt-blue light. Treatment consists of cycloplegia, erythromycin ointment, and pressure patching overnight. Oral narcotic analgesia is sometimes necessary.

Treatment:

1. Instill cycloplegic agent: 1% cyclopentolate or 0.25% scopolamine, one drop in each eye; this may be repeated by the patient q 6 to 8 h if needed for pain reduction.

2. Erythromycin ophthalmic ointment now, then qid once the patch is removed.

3. Pressure patching for comfort for the first 24 h; bilateral is preferable but seldom practical.

4. Consider oral narcotic analgesia if pain is severe.

5. Ophthalmology referral within 48 h (this condition is usually self-limited, with complete recovery). ACUTE VISUAL REDUCTION/LOSS

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