Keratoconus: The Masquerade.

Abstract

Abstract We describe the case of an 11-year-old girl with a background of anisometropia and corneal scarring who had a misleading appearance of keratoconus. The patient initially presented at age 6 with a unilateral reduction of visual acuity (VA) in her left eye (6/15). There was also evidence of left corneal scarring which appeared chronic; possibly secondary to previous herpes simplex keratitis (HSK). She was treated with glasses and though her vision initially stabilized (VA 6/6 in both eyes), she was lost to follow-up due to multiple missed appointments. Her vision remained stable for 5 years before she presented with another reduction of VA in her left eye (6/48). The patient was investigated using Pentacam which showed ectatic changes suggestive of keratoconus. There was also progression of the corneal scar in her left eye. With an impression of active stromal herpetic keratitis, the patient was commenced on 200 mg Acyclovir TDS and Dexamethasone minims TDS. 2 months later, her VA improved to 6/7.5 in the left eye. Pentacam was then repeated and the astigmatism, as well as anterior steepening values had reduced. Considering this, clearly HSK had led to a misleading appearance of keratoconus upon initial imaging. This case highlights the potential false positive diagnosis of keratoconus that can occur in younger patients with HSK. Although pentacam results showed advanced ectasia, one should remain mindful of differential diagnoses; particularly seeking out any signs of herpetic eye disease and keeping a low threshold for appropriate treatment.