A new, minimally invasive procedure appears to be effective for many patients with Fuchs endothelial dystrophy (FED), a common eye disease, without the potential side effects and cost of the current standard of care, a cornea transplant.
In a proof-of-concept study, published in the journal Cornea, researchers led by Kathryn Colby, MD, Ph.D, the Louis Block professor and chairman of the Department of Ophthalmology and Visual Science at the University of Chicago, showed that removing a few square millimeters of a single layer of cells on the inside of the cornea allowed rejuvenation of the surrounding tissue, without the need for a corneal transplant. This simple procedure restored clear vision to three out of four patients suffering from FED, the most frequent cause for corneal transplantation in the United States.
Over the past two years while at Harvard Medical School, Colby performed the new procedure, known as Descemet stripping, on 11 patients, aged 51 to 91. Two patients had the procedure in both eyes, one at a time.
When assessed six months after the operation, ten of the treated eyes (77 percent) had clear corneas and eight had 20/20 vision or better (two patients had retinal disease that limited their final vision). The other three eyes did not respond and required a standard cornea transplant.
“It’s too soon to call this a cure,” Colby said. “We performed the first operation just over two years ago. But when it works, it’s a wonderful thing. It’s quick, inexpensive and it spares patients from having someone else’s cells in their eyes, which requires local immunosuppression.”
Descemet stripping involves removing a small patch of the corneal endothelium (the pumping cells that stop working in FED) attached to an underlying layer (the Descemet membrane). In patients with FED, water accumulates in the cornea, the clear front window of the eye, because of the dysfunction of the pumping cells, causing reduced vision, glare and haloes. If left untreated, the condition progresses to painful blindness.
Removal of the central dysfunctional cells enables healthier peripheral cells to migrate to the center of the cornea, where they reestablish pumping capacity and removal of fluid from the layers above. This gradually restores clear vision.
In 2015, 14,000 corneal transplants were performed in the United States, just for FED, the most common reason for this operation. The transplants work well, but the tissues are expensive and there is a limited supply in some areas of the world. Because the corneal transplant tissue is foreign, patients must apply topical steroids for the rest of their lives to dampen their immune response and prevent rejection of the transplanted cells. Steroid eye drops are known to cause glaucoma and cataract and can predispose to infection.
The researchers classified patients into four groups based on how they responded to Descemet stripping. Fast responders regained clear vision within a month after surgery. Responders recovered within three months. Slow responders took more than three months. Nonresponders had persistent corneal edema and required endothelial keratoplasty–a streamlined cornea transplant.
Of the 13 eyes treated, four were fast responders, four were responders and two were slow responders.
The next step is to try to understand why some patients, about one out of four, don’t respond to removal of the dysfunctional cells. Fuchs dystrophy is a polygenic disease, but in the last few years researchers have found connections between the extent of a repeating nonsensical genetic abnormality seen in other neurological diseases and the severity of FED. Colby hopes to find genetic clues that predict which patients are most likely to respond to this approach.
