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Ophthalmology – Chemical Burns
Chemical burns of the eye are serious ocular injuries caused by exposure to corrosive substances such as acids, alkalis, or irritants including solvents and oxidizing agents. These injuries may affect not only the ocular surface but also surrounding facial tissues and, in severe cases, deeper intraocular structures. Alkali burns are generally more severe than acid burns because they penetrate tissues rapidly and cause extensive cellular damage. Chemical eye injuries account for approximately 7–10% of all ocular trauma and are most commonly occupational, particularly among men due to higher industrial exposure.
The severity of injury depends on both the nature of the chemical and the duration of exposure. Alkalis (e.g., ammonia, sodium hydroxide) cause saponification of cell membranes and deep tissue penetration, leading to widespread destruction. In contrast, acids tend to cause protein coagulation, forming a barrier that limits deeper penetration (with the exception of hydrofluoric acid). Damage mechanisms include protein denaturation, collagen disruption, vascular ischemia, and depletion of essential substances such as ascorbate, which impairs healing.
Patients typically present with acute symptoms such as severe pain, photophobia, tearing, blurred vision, and involuntary eyelid closure (blepharospasm). A detailed history, including the type of chemical exposure, is critical. On examination, findings may include corneal epithelial defects, limbal ischemia (seen as pale or blanched areas), stromal haze or opacity, conjunctival damage, and anterior chamber inflammation. In severe cases, there may be elevated intraocular pressure, iris damage, or even lens and ciliary body involvement. The injury evolves through acute, intermediate, and late stages, with potential complications including corneal melting, ulceration, scarring, and symblepharon formation.
Diagnosis is primarily clinical, supported by pH testing of the ocular surface to determine whether the offending agent is acidic or alkaline. Grading systems such as Dua’s classification assess the extent of limbal and conjunctival involvement and help predict prognosis. It is important to recognize that clinical findings can evolve rapidly, and repeated assessment is essential.
Management is an ophthalmic emergency and begins immediately with copious irrigation of the eye using saline or balanced solutions, ideally before full examination. The goal is to normalize the ocular surface pH to around 7. After irrigation, any retained particulate matter must be removed. Medical therapy includes intensive lubrication, topical antibiotics to prevent infection, and cautious use of topical steroids to control inflammation. Additional treatments may include ascorbate (to promote collagen synthesis), citrate (to inhibit tissue breakdown), cycloplegics for pain relief, and intraocular pressure–lowering medications if needed. Pain control and supportive care are also essential.
In more severe cases, advanced therapies such as autologous serum drops, amniotic membrane transplantation, or limbal stem cell transplantation may be required. Surgical interventions may also address complications like glaucoma, corneal perforation, or eyelid deformities. Long-term follow-up is crucial to monitor healing and prevent complications.
The prognosis depends largely on the depth and extent of injury. Superficial burns have a good outcome, while severe burns involving the entire limbus and conjunctiva carry a poor prognosis with a high risk of vision loss. Complications can include limbal stem cell deficiency, corneal scarring, glaucoma, cataract formation, and even loss of the eye. Early and aggressive management is critical in improving visual outcomes.
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