Cutting-edge advances in corneal treatment

Kamran M. Riaz, MD, clinical associate professor and director of medical student education at the Dean McGee Eye Institute at the University of Oklahoma, discussed some of the latest trends in corneal treatment in our July/August issue.

Kamran M Riaz, MD

Refractive trends

“We’re seeing more and more surgeons doing…small incision lenticule extraction [SMILE],” he said. “I personally have not done SMILE. But I know that more and more surgeons are offering that.”

Another trend is topography-guided refractive surgery. Guided with the totaliser, this procedure is increasingly being used in patients with keratoconus who undergo cross-linking.

“Many surgeons now feel comfortable with cross-linking patients, waiting for at least a year to have stability,” he explained. “Some of our European colleagues are maybe a little bit more cavalier and go ahead and just do it at the same time.”

Cross-linking

US surgeons have developed data on performing cross-linking and subsequently waiting and documenting that there is no keratoconus progression, Riaz noted. “This is followed by…topography-guided photorefractive keratectomy (PRK)…sometimes combining that…with a phakic IOL first and then doing minimal PRK to correct some of the astigmatism and irregular corneal topography,” he explained. “And finally…we’ve seen a reemergence of Intacs along with cross-linking.”

According to Riaz, cross-linking was approved in 2016 and many surgeons, himself including, used to employ Intacs because it was a good treatment for keratoconus.

“We weren’t able to help the disease process,” he said. “So, the nice thing about now with crosslinking, is we’re able to, and again, different surgeons have different philosophies on this. Some people want to do the crosslinking first, and then do the Intacs.”

Riaz is in the latter group.

“The last review or meta-analysis I read on that, which was maybe about a year ago, showed that both are viable options and are effective, but…doing the Intacs first and then the cross-linking certainly has a better refractive and corneal flattening effect.”

Bowman’s membrane transplant

Interest in Bowman’s membrane transplantation has been increasing, Riaz added, but he noted it remains to be seen whether it will become a mainstream option because the surgery and preparation of the membrane are both difficult.

“If the eye banks can start doing that, it would certainly be viewed more and more as a therapeutic option,” he said, but “it’s still just a living bandage contact lens for keratoconus.” Although he hasn’t offered this option to patients yet, Riaz is optimistic about it and will wait to see how patients react to it.

Rho kinase inhibitors

Rho kinase inhibitors typically treat diabetic retinopathy by slowing leukocyte-induced damage and decreasing the adhesion of leukocytes. As an intravitreal injection, the inhibitor slows the synthesis of various downstream proteins in the Rho pathway as well as in ICAM-1.

“We are seeing more and more exploration of expanding the role of Rho kinase inhibitors,” Riaz observed. “People are using it, obviously for Descemet stripping only (DSO), but I believe people are now maybe wondering if there is a use for Rho kinase inhibitors for limbal stem cell deficiency.”

The future

Surgeons seem to be waiting for the holy grail—injectable endothelial cells—Riaz noted, adding that studies have demonstrated the concept, and the concept has worked in a limited number of patients.

It could even prove revolutionary and replace Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). “I do a lot of DMEK now. Especially with preloaded tissue the eye banks have, there’s a variety of different options,” he said. “Preloaded DMEK…has made DMEK a more efficient option.”

In the past, surgeons would have had to prepare their own tissue, but advances may be making the injections much safer. “We may find that injecting endothelial cells is much safer,” he pointed out. “And the irony would be [that] for years, we had patients lie on their back looking up at the ceiling, and now we may end up having to follow our retina colleagues’ lead and have them look down at the floor.”

Surgeons are also awaiting FDA approval of epithelium (EPI)-on cross-linking, which is being performed in many other parts of the world. “People here in the United States that were part of the trials all say EPI-on works great,” Riaz remarked. “One of the challenges of doing cross-linking is that these patients are miserable for a day or two. If we can save the epithelium, that would be great.”

Riaz has been doing cross-linking for 4 years at Dean McGee and has seen patients develop infections after forgetting to instill their antibiotic eye drops or after removing lenses with steroid drops.

“The bottom line is that EPI-on is going to be a really a huge thing for corneal disease and doing cross-linking,” he said.

Riaz said he would also like to see device options domestically, including accelerated protocols, and even slit-lamp protocols through a contact lens.

Something else Riaz has noticed is that the number of surgeons performing cross-linking has steadily declined because they can’t make any money from the procedure. “That’s a shame,” he said. “We know cross-linking works. It can save people from having to do a corneal transplant. And what may end up happening is that folks like myself and academic centres end up having to do all these cross-linking procedures.”

3D-printed corneal inlays

Riaz also addressed 3D corneal inlays for the treatment of presbyopia. “We may find that with further refinement, there is a role for these types of devices for the treatment of presbyopia,” Riaz pointed out. “I would love to see some options for patients emerge so that it can be offered to them.”

He is “cautiously optimistic” because devices that have made it to the market in the past ended up being pulled. Another advance is the use of 3D-printed corneal tissue.

Scientists at the National Eye Institute recently announced that they have used patient stem cells and 3D bioprinting to create eye tissue that is advancing scientific understanding of how eye diseases develop and degenerate.

Researchers have printed cells that form the outer blood-retina barrier and that will mean future researchers will have an unending supply of tissue to study.

“I think a 3D-printed stromal tissue contact lens could be used for cross-linking and could even be made compatible for human transplantation or for use as a patch graft for injuries in war zones,” Riaz said. “When tissue isn’t available, this could be a viable option."

Kamran M. Riaz, MD – E: emailaddress@email.com

Dr Riaz has no financial disclosures related to this content.