The blink reflex usually causes the eye to close in response to a thermal stimulus. Thus, thermal burns tend to affect the eyelid rather than the conjunctiva or cornea. Eyelid burns should be cleansed thoroughly with sterile isotonic saline solution followed by application of an ophthalmic antimicrobial ointment (eg, bacitracin bid). Most thermal burns affecting the conjunctiva or cornea are mild and heal without significant sequellae. They are treated with oral analgesics (acetaminophen with or without oxycodone), cycloplegic mydriatics (eg, homatropine 5% qid), and topical ophthalmic antibiotics (eg, bacitracin/polymyxin B ointment or ciprofloxacin 0.3% ointment qid for 3 to 5 days).
Chemical burns of the cornea and conjunctiva represent 11 to 22% of ocular trauma and can be serious, particularly when strong acid or alkali is involved. Alkali burns tend to be more serious than acid burns.
Chemical burns should be irrigated copiously as soon as possible. The eye may be anesthetized with one drop of proparacaine 0.5%, but irrigation should not be delayed and should last for at least 30 min. Some studies show sterile sodium chloride (saline) solutions (and particularly certain types) are optimal, but water can be used if sterile saline is not immediately available. Irrigation may be facilitated by using an irrigating lens placed under the lids, although this can be more irritating to some patients than irrigation without such a lens. In acid and alkali burns, some experts suggest 1 to 2 L of irrigation; most experts recommend irrigation until the pH of the conjunctiva is normal (using expanded pH paper).
After irrigation, the conjunctival fornices should be examined for chemical embedded in the tissue and swept with a swab to remove trapped particles. The superior fornices are exposed by using double eyelid eversion (ie, first everting the eyelid and then inserting a swab under the everted eyelid and lifting it up until the fornix is visible).
Mild chemical burns are generally treated with topical ocular antibiotics (eg, erythromycin ointment 0.5%) 4 times/day and cycloplegia if needed for comfort (eg, cyclopentolate). Because topical corticosteroids can cause corneal perforation after chemical burns, they should be given only by an ophthalmologist. Topical anesthetics should be avoided after initial irrigation; significant pain may be treated with acetaminophen with or without oxycodone. If the patient's renal function is not impaired, oral vitamin C (2 g qid in adults) can be used to help with collagen synthesis. Oral doxycycline can also be used in appropriate patients to stabilize collagen, but both of these practices should be done with consultation with an ophthalmologist.
Severe chemical burns require treatment by an ophthalmologist to save vision and prevent complications such as corneal scarring, perforation of the globe, and lid deformities. Patients with severe decreased vision, avascular areas of conjunctiva, or loss of conjunctival or corneal epithelium as demonstrated by fluorescein staining should be examined by an ophthalmologist as soon as possible and no longer than 24 h after the exposure.
Chemical iritis is suspected in patients with photophobia (deep eye pain with exposure to light) that develops hours or days after a chemical burn and is diagnosed by finding flare and WBCs in the anterior chamber during slit-lamp examination. Chemical iritis is treated by instilling a long-acting cycloplegic (eg, a single dose of homatropine 2% or 5% or scopolamine 0.25% solution).