ACANTHAMOEBA

Painless acanthamoeba keratitis can bring about a rapid loss of vision and can prove very resistant to therapy, according to Emiliano Ghinelli MD, who presented a case study at the Cornea Day session of the 16th ESCRS Winter Meeting. The case involved a young man who wore contact lenses and whose visual acuity suddenly decreased to counting fingers over the course of a few days. The affected eye had minimal anterior epithelial debris, very mild limbus inflammation, no Tyndall effect, and no pain, said Dr Ghinelli MD, Ospedale Civile di Volta Mantovana, Volta Montavana, Italy.

“We didn't know it was acanthamoeba at first, but since this case we have collected reports of similar cases. This guy was really young and he was a pizza maker so this gave him a history of thermal exposure. It was a very sudden onset he went to counting fingers in just a few days,†he said The early management of the case consisted of topical wide spectrum antibiotics, topical non-steroidal anti-inflammatory drugs, topical cycloplaegics, topical antiamoebic drugs. Dr Ghinelli and his associates also performed a double-layer amniotic membrane transplant on the ocular surface

In addition, they took bacterial and fungal cultures from the eye and performed PCR testing on scraped epithelial debris to check for the possible presence of herpes simplex virus and acanthamoeba. During the first 10 days after the amniotic membrane transplant, the eye seemed to respond pretty well, becoming less inflamed and stabilising in terms of most disease parameters, Dr Ghinelli said. However, after that period the eye returned to the condition it was at presentation, he added. Dr Ghinelli and his associates then performed a conjunctival graft, which quickly became perforated, necessitating the performance of a penetrating graft. Despite the presence of major anterior chamber inflammation and major anterior uveitis, and a procedure which involved the removal of fibrin from the angle and some additional difficult manoeuvres, the eye looked fairly good during the first three postoperative months, Dr Ghinelli said. However, graft rejection occurred at the third month of follow-up, followed by corneal melting a month later. He added that they have since washed out the conjunctiva of any of the toxicity from the anti-amoebic agents and are administering wide spectrum antibiotics, systemic steroids, and systemic voriconazole. They are also contemplating performing a penetrating keratoplasty with the PCR-testing of the rejected graft. They may also perform collagen cross-linking as an antimicrobial treatment while continuing with the systemic steroid and voriconazole regimen. He noted that some authors have reported good results with systemic voriconazole in the treatment of chronic stromal acanthamoeba keratitis. The concentrations used in those reports is 200mg once or twice daily for three months, always monitoring kidney and liver function.

“We’re creating a database of all the painless cases of acanthamoeba keratitis that resemble this case, and incredibly, there are an increasing number of cases of acanthamoeba in our area that all look like this,†Dr Ghinelli added.