PK may be successful treatment for parasitic keratitis

Acanthamoeba keratitis, often associated with contact lens use, can be difficult to diagnose.

Issue: April 15, 2002

ByLou Koury

SÃO PAULO, Brazil — Penetrating keratoplasty appears to be effective for treating keratitis caused by Acanthamoeba.

“We prospectively followed 52 patients who had keratoplasty for the treatment of keratitis from Acanthamoeba. Two patients had infection in both eyes,” said Denise de Freitas, MD, of the São Paulo Federal University here.

Researchers made the diagnosis with corneal scrapings and biopsy, she said. Patients were treated with intensive topical therapy, including biguanide and propamide for a prolonged period. Some patients received additional neomycin treatment, four times daily for 10 days.

Dr. de Freitas reported that 11 patients did not respond to medical treatment, and had worsening signs and symptoms, including dilated pupils, anterior synechiae, iris atrophy and glaucoma.

“We don’t know why, but our patients were developing these findings of severe anterior synechiae, glaucoma and iris atrophy,” she said.

The surgeons performed corneal grafts with lens extraction, IOL implantation and iridoplasty.

Of the 53 eyes, Dr. de Freitas reported, 20 underwent penetrating keratoplasty. Excised corneas were cultured and analyzed by histopathology for Acanthamoeba.

Seven had positive cultures and 11 had positive histopathology findings.

“Three patients had both exams positive for Acanthamoeba. We had just two patients with recurrence after keratoplasty,” she said.

On follow-up, four patients had graft rejection. Five patients had secondary glaucoma and one eye evolved with loss of light perception. One eye suffered atrophy.

“We always ask if we should delay surgery in Acanthamoeba keratitis,” Dr de Freitas said. “We think that as soon as we detect complications like anterior synechiae, dilated pupil, iris atrophy and glaucoma, we should do surgery as soon as possible.”

	Stromal ring infiltrate in Acanthamoeba keratitis.
*Patient with a severe Acanthamoeba* sclerokeratitis (left).** Acanthamoeba keratitis (right) causing dilated pupil, iris atrophy and cataract.
Anterior synechia (left) and dilated pupil in Acanthamoeba keratitis. Ultrasound biomicroscopy (right) showing extensive anterior synechia in Acanthamoeba keratitis.

For Your Information:

Denise de Freitas, MD, can be reached at the Ophthalmology Department at Federal University of São Paulo, Rua Botucatu, 820 Cep 04023-062 Brazil; (55) 11-5085-2015; fax: (55) 11-5549-6824; e-mail: dfreitas@pobox.com.