Brian Breidenbach has never taken his vision for granted; due to a rare genetic eye disorder, it’s been slowly slipping away for decades.

Recently, his work as a software developer was becoming increasingly challenging, and he anticipated needing to quit driving sooner than later.

“I was really having to contemplate what my life was going to be,” says the 63-year-old from East Grand Forks, Minnesota.

Like his mother, two of his siblings, and two nieces, Breidenbach has aniridia, a rare genetic condition where the iris of the eye doesn’t develop normally. People with aniridia are more likely to develop glaucoma, cataracts, and corneal abrasions and scarring—which can eventually cause blindness.

It’s a poorly understood condition, and until now the only treatment has been corneal transplant. Like other transplants, corneal transplants come with a host of risks, including rejection of the transplanted tissue. Infection, inflammation, and retinal detachment can also result.

But today, thanks to a new type of corneal transplant developed by Joshua Hou, MD, an M Health Fairview ophthalmologist and medical director of the Lions Gift of Sight eye bank, Breidenbach sees a brighter future.

A new approach

Breidenbach is part of a 20-patient clinical study spearheaded by Hou, who’s also an associate professor in the University of Minnesota Medical School Department of Ophthalmology and Visual Neurosciences. The trial revolves around a new type of corneal transplant procedure that Hou pioneered called a DMAK, or Descemet’s membrane anterior keratoplasty.

Breidenbach underwent the DMAK procedure last summer as part of the study. The results, he says, have been “tremendous.”

“It’s pretty exciting when the surgeon is looking at your eye through the scope and saying ‘Amazing! Fantastic!’”

DMAK averts the risks of traditional corneal transplant. It involves removing scar tissue from the patient’s eye, then placing a ring-shaped membrane from the back of an organ donor’s cornea—from an area called Descemet’s membrane—onto the front of the eye. Over time, the eye’s limbal stem cells multiply, giving the person a “clear ocular surface,” Hou says.

People who have aniridia lack limbal stem cells on their eyes, so they can’t keep growing the clear epithelium that protects the cornea—which leads to scarring and ulceration.

“Also, skin from the white of your eye, or from your eyelid, will grow over your eye,” Hou explains. “The corneal epithelium is very unique; you need it to maintain the clarity of your cornea.” DMAK offers a new way to spur its growth.

Minimal risk, minimal discomfort

Hou says DMAK, which he’s been developing for nearly a decade, grew out of earlier research showing that proteins in the Descemet’s membrane strikingly resemble the missing limbal stem cells in people who have aniridia.

“We believe the membranes on the back of that [donor] cornea can actually stimulate the growth of residual stem cells on the surface of the eye,” Hou says.

Since those residual stem cells are the patient’s own cells—not the donor’s—there’s no need for immunosuppression and no risk of rejection. And the outpatient procedure takes under an hour, with minimal discomfort. It’s also reversible.

As of early January, Hou had completed 16 of 20 surgeries involving people who enrolled in the study. While Breidenbach’s results appear to be the most dramatic, being that his corneal scarring was less severe than that of others, Hou says, every participant has seen positive change. And some 40 other surgeons around the U.S. have tried the experimental procedure—all with promising results.

More than storage

Lions Gift of Sight, an eye biobank that stores donated corneas that are both suitable for transplantation and available for research, depending on quality, is a part of the Medical School’s Department of Ophthalmology and Visual Sciences. The biobank, which was an essential resource for Hou as he perfected the DMAK, has been supported by the Minnesota Lions for more than 60 years.

“There are larger eye banks, but we are one of the leaders in research—on a national and even a global scale,” Hou says. “The eye bank is actually the perfect place to do translational research.”

No longer merely a storage facility (as eye banks were for decades), Lions Gift of Sight has its own team of researchers and has evolved to be a “tissue processor,” preparing corneas for transplantation and for study.

Besides people who have aniridia, Hou’s investigational DMAK procedure also offers promise to those who have corneal scarring from injuries or burns. Hou hopes that once the study is complete, his team might get approved for clinical trials involving younger patients—aiming for early intervention, before corneal damage progresses.

Breidenbach lights up at that prospect. “It’s easy to get selfish about it because I’ve seen results,” he says. “But thinking about other people having that—I’m excited! 

“It feels like being brought back from the brink of not being able to do the things that I love doing. This has been such a gift.”