Artificial endothelial layer reduces corneal edema, pain
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A polymer film implant attached to the posterior corneal surface can treat corneal edema secondary to endothelial dysfunction and may be an alternative to endothelial keratoplasty.
“I started using it 2 years ago in two patients who were desperate cases of bullous keratopathy. They had had Descemet’s membrane endothelial keratoplasty and re-DMEK, and there was essentially nothing else we could do. The implant reduced the cornea from 700 µm to 800 µm down to 500 µm, took the pain away, and after 2 years, it is beautifully stable in its place,” Gerd Auffarth, MD, PhD, said in an interview with Ocular Surgery News.
The EndoArt artificial endothelial layer (EyeYon Medical) is a minimally invasive dome-shaped hydrophilic acrylic implant that adheres to the posterior cornea, creating a synthetic barrier to the excess fluid. It was designed by Ofer Daphna, MD, a cornea specialist and medical director of EyeYon Medical.
“I developed the idea approximately 11 years ago, when I was still in my training as a resident. A lot of people were against it, vigorously so, and I had to fight my way through,” Daphna said.
A decompensated, disrupted endothelium leads to overhydration of the cornea, resulting in corneal edema. While endothelial keratoplasty aims at reestablishing endothelial function by replacing the damaged endothelium with healthy donor tissue, the EndoArt artificial lenticule simply blocks a certain portion of the posterior cornea, preventing the excessive transfer of fluid that causes the edema.
“It rebalances hydration,” Daphna said. “It compensates for a function that a damaged endothelium has lost, that is blocking part of the fluid that enters the cornea.”
The artificial lenticule is placed centrally, covering about 40% of the posterior corneal surface. The remaining outer rim of uncovered surface provides the right amount of water filtration to ensure nutrition of the overlying tissue. A new balance is created that reduces the edema and maintains corneal function and health.
Multicenter trial
So far, 20 patients have undergone this procedure in a multicenter study at sites in Israel, Germany, Spain, the Netherlands and India. Eleven patients have between 6 months and 20 months of follow-up. In nine patients, vision has improved from finger counting to 6/40 or from hand motion to 6/60.
“Unfortunately, this group of patients had low visual potential. At least 50% were at the end of the road of what DMEK or DSEK could offer,” Daphna said, adding that up to four grafting procedures were rejected in some patients. “There was no sense in continuing to implant tissue. Others were not suitable for DMEK and DSEK, like people with anterior chamber IOLs, pigment dispersion, glaucoma valves or high IOP.”
Data are lacking regarding how the implant works in more normal eyes with corneal edema, Daphna said.
“Within the multicenter trial, I have treated two other cases. One was a challenging eye with corneal edema, previous vitrectomy and a retropupillary-fixated lens. The other was also a patient with no other option and severe pain from very thick bullous keratopathy. Both surgeries went well, the edema was successfully reduced, and pain has gone. As the study requires, we are treating only desperate, last-resort cases, but in the future, I expect it will be used also in normal cases,” Auffarth said.
Short learning curve
Surgery is the same as for endothelial transplantation but significantly easier, according to Auffarth. First, the stage of donor dissection is eliminated. The artificial layer is easy to handle because it is not as delicate and flimsy as the human donor graft. It does not need staining and is easily inserted and centered with a spatula. Air bubbling is then performed to make the implant adhere to the posterior corneal surface.
“It is not quite clear if you should or should not strip the Descemet’s membrane. The first cases I treated had already had DMEK before, and in the last two cases, the study protocol required removal of the endothelium. Theoretically, the endothelium and Descemet’s could be left in place because this procedure does not rely on a cellular mechanism but on a mechanical barrier effect. The question might be whether adherence is better with or without the endothelium in place,” Auffarth said.
Rebubbling or repositioning the implant in case of decentration can be performed as often as needed because there are no cells that can be damaged, he said. The cases treated so far have been difficult cases that needed a lot of individual surgical decisions, but the learning curve itself is short and approachable by surgeons who have no experience with endothelial keratoplasty procedures.
Expanded indications, accessibility
The EndoArt implant is made of the same material as many IOLs, is biocompatible and does not evoke an immune response. This is, Daphna said, another important advantage.
“The eligible patients are more than those for DMEK or DSEK, which are very good procedures but are likely to fail in a certain group of patients,” he said.
An artificial implant could be the answer to the shortage of donor corneas that affects many parts of the world. There would be no cultural or religious barrier for this transplantation procedure.
“Also, you don’t need to have patients on a waiting list for donors. You just order it, and there is a whole big indication area also for temporary use, before you find the donor implant, or to decrease corneal thickness in preparation for DMEK or DSEK,” Auffarth said.
For older patients, there is the advantage of being spared the risk of undergoing a keratoplasty procedure and being on steroids for some time after the operation.
“I believe we will see interesting advancements in the area of artificial implants for different layers of the cornea because the potential advantages are many, and I see this as a possible paradigm change in the future,” Auffarth said.
The EndoArt holds CE mark status in Europe, innovative device status by the Chinese National Medical Products Administration and breakthrough device designation from the FDA.
- For more information:
- Gerd Auffarth, MD, PhD, can be reached at University of Heidelberg, Department of Ophthalmology, INF 400, Heidelberg, D-69120, Germany; email: gerd_auffarth@med.uni-heidelberg.de.
- Ofer Daphna, MD, can be reached at email: ofer@eye-yon.com.
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