Factors linked to failure of corneal transplants

Certain eye conditions appear to put patients at greater risk for having a failed cornea transplant, according the Cornea Donor Study (CDS), a multi-center clinical trial conducted by the National Eye Institute. The study concludes that patients with glaucoma and patients who had corneal swelling following an earlier cataract surgery were more likely to experience failure of the cornea transplant than were other patients in the study.

The findings, reported by Alan Sugar, M.D., in the June issue of Ophthalmology, emerged from a five-year study of 1,090 individuals who had undergone cornea transplants. Sugar is a nationally known cornea surgeon at the University of Michigan Kellogg Eye Center.

The cornea is the clear, dome shaped tissue covering the front of the eye. If it becomes scarred or damaged from disease or injury, corneal transplant surgery may be needed to remove the cornea and replace it with a healthy cornea from a donor. Researchers wanted to know how a patient's diagnosis prior to the transplantation would affect the success or failure of the surgery.

Sugar and colleagues observed that patients who had been diagnosed with corneal edema (swelling) following an earlier cataract surgery experienced a failure rate nearly four times that of patients diagnosed with Fuchs' dystrophy, a disorder affecting the endothelial layer of the cornea.

The failure rate for patients with corneal edema was 27% compared to 7% for those with Fuchs' dystrophy. The higher rate applied to patients who had their natural lens replaced by an intraocular lens (IOL) during the cataract surgery as well as to those who did not receive a replacement lens.

The study also found that patients with glaucoma had substantially higher failure rates than those who did not have the disease. The risk of failure for patients who did not have glaucoma was 11 percent. By contrast, individuals with glaucoma experienced failure rates of 20 percent, 29 percent and 58 percent, for those treated with medications alone, surgery alone, or both, respectively.

"These findings, and others from the CDS, will help to predict the outcomes of corneal transplant surgery and to develop strategies for improvement in future results," says Sugar.

The study also reported that such factors as age, gender, diabetes and smoking history were not strongly associated with graft failure. The patients in the study were considered to have a moderate risk of failure for transplantation.

Some 40,000 cornea transplants are performed in the U.S. each year, according to the American Academy of Ophthalmology. From 5 percent to 30 percent are rejected, though many rejections can be stopped with treatment.