injuries poisoning
Ocular Burns
Chemical burns
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 cause liquefaction necrosis, whereas acid burns cause coagulation necrosis. Because of this difference, alkali burns have deeper penetration and tend to be more serious than acid burns. Chemical burns to the cornea and conjunctiva are a true emergency; treatment must begin immediately. Chemical burns should be irrigated copiously as soon as possible. The eye may be anesthetized with one drop ofproparacaine0.5%, but irrigation should not be delayed and should last for at least 30 minutes. A hypertonic solution, such as borate buffer solution, may be more effective than other commonly used irrigating solutions at correcting intraocular pH, while a balanced saline solution (a sterile, isotonic solution with a pH of 7.4) is better tolerated by patients allowing for longer irrigation time. But any saline solution or water can be used to avoid delay in irrigation. 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 at least a 30-minute initial irritation with 1 to 2 L; most experts recommend irrigation until the pH of the conjunctiva is in the normal range of 7.0 to 7.2 (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 burnsare generally treated with topical ocular antibiotics (eg,erythromycinointment 0.5%) 4 times a 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 withacetaminophenwith or withoutoxycodone. If the patient's renal function is not impaired, oral vitamin C (2 g 4 times a day in adults) can be used to help with collagen synthesis. Oraldoxycyclinecan also be used in appropriate patients to stabilize collagen, but both of these practices should be done with consultation with an ophthalmologist. Citrate eye drops, to decrease proteolytic activity, and platelet-rich plasma eye drops may also aid in healing and should also be given only in consultation with an ophthalmologist. Severe chemical burnsrequire treatment by an ophthalmologist to save vision and prevent complications such as corneal scarring, perforation of the globe, and lid deformities; severe chemical burns may require surgical procedures in addition to medical treatments. Patients with severe decreased vision, avascular areas of conjunctiva, or loss of conjunctival or corneal epithelium as demonstrated byfluoresceinstaining should be examined by an ophthalmologist as soon as possible and no longer than 24 hours after the exposure. 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 white blood cells 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 