We report an unusual case of a man whose significant myopia was almost completely neutralised after developing herpes simplex keratitis (HSK). Ten months after an acute reactivation in the affected (left) eye, the patient's refractive error was found to have changed from -7.50/-1.25 ¥ 165 to -0.75 DS.
CASE HISTORYA 66-year-old man presented in August 1995 to his optometrist with reduced vision in the left eye. Visual acuity (VA) was OD 6/9 with -7.00/-1.25 ¥ 12 and OS 6/24 with a -7.50/-1.25 ¥ 165. The optometrist noted central corneal haze and referred the patient to hospital, noting that five years previously, the left eye had acuity of 6/9 with an identical correction.The ophthalmologist found an inactive left corneal scar. Four months later, he complained of two weeks of left eye pain and redness. Examination revealed reduced corneal sensation, an active herpes simplex ulcer and stromal keratitis. He was given aciclovir 3% ointment five times per day. Ten days later, the ulcer had healed and topical prednisolone 0.5% tid was started. After four weeks, VA had improved to 6/12 OS but some stromal haze persisted and topical prednisolone was tapered over six months.Four months after stopping prednisolone drops, he attended complaining of anisometropic symptoms with his glasses, saying his left eye saw worse with glasses than without. The left cornea showed subepithelial haze and retinal examination was normal. Left eye refraction was now -1.25 DS. He opted for new glasses. Three months later, he had VA of 6/9 OU. Surprisingly, he had no anisometropic symptoms and was satisfied with the new glasses.By March 1997, the left eye's unaided vision was 6/12 and refraction was -0.75 DS. He produced prescriptions from eye tests dating back over 30 years (Table 1). Topography of both eyes (Figure 1) was performed during the period of emmetropisation in March 1996 and reveals an irregular left cornea with paracentral flattening. The central three millimetre simulated keratometric readings were: OD K1 = 45.14, K2 = 45.27 and OS K1 = 42.81, K2 = 46.17.
DISCUSSIONHerpes simplex virus type 1 (HSV-1) remains a leading cause of unilateral corneal blindness worldwide.1 Recurrence can manifest as blepharitis, conjunctivitis, epithelial keratitis, stromal keratitis, inflammation of the endothelium or iridocyclitis. Although stromal keratitis accounts for only two per cent of initial HSV-1 ocular presentations, it causes 20 to 61 per cent of recurrent disease.
2HSV stromal keratitis can manifest in necrotising or non-necrotising forms. Our patient had the non-necrotising type, also known as immune stromal keratitis. Its pathogenesis is not clear but the hallmark is stromal inflammation, 3 which may be focal, multifocal or diffuse leading to thinning, scarring and neovascularisation of the cornea. 4 These changes can alter corneal curvature or thickness, 5 thereby inducing refractive changes. Induced astigmatism is a well-known sequela of HSK, 6 including in children.7 To our knowledge, there are no reports of HSK causing an alterati...
