Presumed late recurrence of Acanthamoeba keratitis exacerbated by exposure to topical corticosteroids
A 28-year-old female with keratoconus initially presented with a 1 week history of pain and photophobia in her left eye (OS). She was a rigid gas permeable contact lens wearer who admitted to regularly “cleaning” contact lenses in tap water supplied from a water tank. On examination, her best spectacle corrected vision (BSCVA) was 20/20 OD and 20/32 OS. A dendritic-like epithelial lesion was observed on the left cornea and she was treated with oc. acyclovir 5 times daily for presumed herpes simplex keratitis. However, 10 days later she remained symptomatic and a persistent dendritic epithelial lesion with granular subepithelial haze was noted. A diagnosis of AK was suspected and in vivo confocal microscopy (IVCM) confirmed the presence of Acanthamoeba cysts in the basal corneal epithelium OS []. A corneal scrape confirmed the diagnosis of AK.\nShe was treated with topical propamidine isethionate (Brolene 0.1%) and chlorhexidine (0.02%), both drops six times daily, with rapid clinical improvement. This treatment was tapered off over 11 months. The keratitis resolved leaving minor, mid-peripheral, anterior stromal scars. She confirmed that she completely discontinued contact lens wear following resolution of the keratitis, but maintained a BSCVA of 20/30.\nFive years later, she represented with a 5 month history of increasing discomfort and photophobia in the left eye although there was no associated redness. She had treated these symptoms herself intermittently with non-prescribed, across-the-counter Brolene 0.1% eye drops but as her symptoms failed to settle, she consulted her optometrist who prescribed topical corticosteroids without further investigation. Her symptoms initially improved, however, 3 weeks later she presented to the ophthalmology service with increasing pain and reduced vision. BSCVA was 20/30 OS and slit-lamp examination revealed localized, inferior corneal stromal edema []. IVCM confirmed Acanthamoeba cysts at the level of the basal epithelium []. Although there were no obvious cysts visible in the stroma, the view was partially obscured by stromal haze []. In view of the history, clinical findings, IVCM results, and absence of an epithelial defect; a corneal scrape was not performed. Treatment with topical polyhexamethylene biguanide (PHMB) 0.02% and Brolene 0.1% were commenced hourly by day and the keratitis subsequently improved over the following 4 weeks. The treatment was tapered over 9 months and she retained a BSCVA of 20/30.