Stromal opacity secondary to preservative in dilating drops - A case report and review of literature

Preservatives in ophthalmic solutions have long been known to cause toxic effects on the cornea. The most frequently used preservative in eye drops, and one that has among the highest toxicity, is benzalkonium chloride (BAC)[1-3]. This quarternary ammonium has been shown to have a variety of pathological effects, including tear film instability, conjunctival squamous metaplasia, breakdown of conjunctival immunological tolerance and cytotoxicity of corneal epithelial, stromal, and endothelial cells[4-7]. Clinically, use of BAC may cause dry eyes, red eyes, itchy eyes, photophobia, and other signs of ocular irritation[8]. Consequences of the use of these preservatives in the eye have included chronic inflammation and hypersensitivity reactions like cicatricial pemphigoid and Steven -Johnson’s syndrome[2,7,9]. BAC plays an important role in ocular surface damage, especially as its effects are doseand time-dependent[4,8]. In our unusual finding, the patient developed stromal opacity almost immediately after one instillation of topical tropicamide containing benzalkonium chloride, and to the best of our knowledge, this is the first reported case of such a condition.