Outcomes positive 7 years after keratoprosthesis implantation

There was a 50% probability of patients maintaining a visual acuity of 20/200 or better at the 7-year follow-up.

Issue: October 10, 2014

Eyes treated with a Boston type 1 keratoprosthesis showed positive results and lasting effects during a 7-year period, according to a study.

In a study published online ahead of print in Ophthalmology, study authors examined patients who underwent implantation of a Boston type 1 keratoprosthesis (KPro) and found that, in a 7-year period, many patients achieved and retained useful vision despite increased complications with longer follow-up.

Esen Karamursel
Akpek

“The study does demonstrate that long-term outcomes are good — 70% at 7 years is good considering that these patients do not have any other option,” Esen Karamursel Akpek, MD, told Ocular Surgery News.

Methods

The retrospective study included 139 eyes of 133 patients who underwent KPro implantation between 2003 and 2006 at five tertiary referral centers. The study authors collected patient information from 2011 to 2012, and the information was entered into a database for analysis.

For the analysis, eyes were split into five groups based on the indication for implantation: ocular surface disease, congenital corneal abnormalities, infectious keratitis, bullous keratopathy/corneal dystrophy and unknown. Visual acuity was recorded 6 months postoperatively and at least once a year afterward.

Follow-up should be frequent after KPro implantation, according to Akpek.

“Every 6 weeks our patients see a doctor — an optometrist or an ophthalmologist. The person exchanges the contact lens, checks the digital pressure, checks the eye with a slit lamp and all that. Additionally, every 3 to 4 months for the first and second year, we see the patient at our practice,” she said.

Postoperative outcomes

Before KPro implantation, 10.8% of patients had a visual acuity of 20/200 or better. Visual acuity improved to 20/200 or better in 70% of patients after implantation, with 50% probability of patients maintaining a visual acuity of 20/200 or better at the 7-year follow-up. Estimated retention rate was 67%, and mean follow-up was 46.7 months.

“If you look at the Kaplan-Meier survival curves, the retention rate does stabilize after 4 years,” Akpek said. “The study does not address who is the best candidate for this type of surgery. There are some patients who are 7 years out and have maintained their best corrective vision ever and there are some patients who have failed within the first 2 years.”

Regarding postoperative complications over the 7 years, the cumulative incidence of retroprosthetic membrane formation was 49.7%; 21.6% of eyes had glaucoma surgery, 18.6% had retinal detachment and 15.5% had endophthalmitis.

Previously, major complications included melt around the device, device extrusion, endophthalmitis and retinal detachment. But now that the device has been improved with the penetrating back plate and the postoperative regimen has been changed to include antibiotics on a long-term basis for high-risk patients, devices stay implanted longer, which means glaucoma has become a major complication, according to Akpek.

“I think that glaucoma is the major issue in the postoperative period, so we have to find better protocols in regard to how to follow glaucoma, how to detect worsening of glaucoma and how to treat glaucoma,” she said. “Who is the best candidate for the surgery? I think that requires prospective studies where we compare repeat donor corneal transplant with artificial transplant and see what patient will do well with which type of corneal surgery.” – by Nhu Te

Reference:

Srikumaran D, et al. Ophthalmology. 2014;doi:10.1016/j.ophtha.2014.05.030.

For more information:

Esen Karamursel Akpek, MD, can be reached at Ocular Surface Diseases Clinic, The Wilmer Eye Institute, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Maumenee #317, Baltimore, MD 21287; email: esakpek@jhmi.edu.

Disclosure: Akpek has no relevant financial disclosures.