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August 2009
 

REFRACTIVE SURGERY

 

Treating Acanthamoeba keratitis with PK


by Maxine Lipner Senior EyeWorld Contributing Editor

 

 

 

Comparing medically to surgically resolved outcomes

Patient with Acanthamoeba keratitis Source: Anna S. Kitzmann, M.D.

Penetrating keratoplasty for those with active Acanthamoeba keratitis infections offers much spottier outcomes than in cases where the condition has been cured medically first, according to Anna S. Kitzmann, M.D., assistant professor of ophthalmology, University of Iowa, Iowa City. Dr. Kitzmann reported on results in the May 2009 issue of Ophthalmology.

In general, Dr. Kitzmann finds that such infections usually occur in patients who wear contact lenses. “Eye pain, decreased vision, and redness are typically the signs,” she said. There are a few medical options here. “This is treated medically with various anti-Acanthamoeba drops and potentially oral medications such as fluconazole [Diflucan, Pfizer, New York, N.Y.] or ketoconazole [Nizoral, McNeil Consumer Healthcare, Fort Washington, Pa.],” Dr. Kitzmann said. Even in the best of cases, this can be extremely challenging to manage. “In general, this is a very difficult infection to treat, and in some cases, despite all of the appropriate medical management, either the infection continues to progress or it just doesn’t respond to medical management,” Dr. Kitzmann said. “In those cases a corneal transplant can be done to excise the infected area.”

Reviewing Acanthamoeba cases

With many cases of Acanthamoeba keratitis occurring in the vicinity, investigators here set out to see how successful corneal transplantation actually was for those patients with the infection. In this retrospective study, they reviewed cases of Acanthamoeba keratitis diagnosed between 1980 and 2007 in patients who had undergone corneal transplants as a result. Patients included here were divided into two groups. “There was a group of about 22 eyes that had such difficult infections that a transplant was necessary,” Dr. Kitzmann said. “Then there was another group where the infection was adequately treated medically but who had significant scarring and decreased vision and required a corneal transplant for that reason.”

When investigators compared how these two groups fared, they found that those who underwent the keratoplasty for visual reasons alone tended to respond better. “We found that the group that had a transplant for what we called an optical penetrating keratoplasty, to restore vision, not because there was necessarily any infection there, those patients tended to do very well,” Dr. Kitzmann said. “They had good visual acuities with almost 90% of the patients having 20/40 or better vision.” In addition, there was usually no need to repeat the keratoplasty procedure in these eyes. “The vast majority, all except for one, only needed one transplant,” Dr. Kitzmann said. By comparison, the group that did have active infections who required a transplant because the disease could not be medically controlled did not fare nearly as well. “Those patients had a poorer prognosis,” Dr. Kitzmann said. Although they were all ultimately cured of their infections, it often required more than one transplant. That took its toll on visual acuity. “On average there was only 50% that had 20/50 vision or better and a higher percentage that were 20/200 or worse,” Dr. Kitzmann said. “Also, graft survival was much worse for those patients that had active infection versus those who just had residual scarring.” Investigators found that patients who needed the grafts strictly for optical reasons did better long term. This finding meshes with previous work in the area. “Many other studies have shown that any time there is active infection with Acanthamoeba or viral, bacterial, or fungal infection, those that need transplants tend to do worse,” Dr. Kitzmann said. “This is probably because there is active infection and the eye is inflamed.”

Clinical perspective

Although those in the active infection group did not fare as well, Dr. Kitzmann is buoyed by the fact that all of the infections were ultimately controlled, with hope of a good visual outcome. “I think that it’s reassuring that of those who needed a transplant when they had infections, although they required multiple transplants, 100% of them were cured of the infection and at least half of them had vision of 20/40 or better,” Dr. Kitzmann said. “There is hope that you can get rid of the infection and have good vision, although in some cases it certainly may require more surgeries to get there.”

Based on the results here, Dr. Kitzmann urges practitioners to take a medical approach to Acanthamoeba keratitis when possible. “I think that the take home message is that if one can wait and try to cure the infection medically and then do the transplant, the prognosis of the graft will be better,” she said. “Unfortunately, sometimes our hand is forced and even under the best care, because patients are in so much discomfort and the infection is so severe, you can’t wait—but if you do have that luxury then the chance of them doing well is very high.”

Editors’ note: Dr. Kitzmann has no financial interests related to her comments.

Contact information

Kitzmann: 319-384-7371, anna.kitzmann@gmail.com







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