NOV 15, 2021
Promising New Artificial Corneas
Corneal blindness continues to be a leading problem around the world, but tackling it is challenging. During her Cornea Subspecialty Day presentation on Saturday afternoon, Marjan Farid, MD, described three artificial corneas currently under investigation that may help.
“This is sort of a holy grail,” she said. “We’ve been looking for the advent of a really good artificial cornea that we can use worldwide.”
Limitations to treating corneal blindness. There are several reasons why it has been difficult to treat corneal blindness in the current climate. Part of the issue is the shortage of both tissue and trained corneal transplant surgeons, as well as the costs associated with surgical procedures. In addition, most procedures continue to have risks of severe complications.
Available options. Currently available keratoprosthesis designs include the Boston KPro, the Moscow Eye Microsurgery Complex in Russia (MICOF) keratoprosthesis, and the osteo-odonto-keratoprosthesis (OOKP). Unfortunately, these options are not practical for the global population. Although useful, these devices can cause complications—particularly infection and glaucoma progression—and fail to effectively integrate with the cornea/sclera.
Emerging options show potential. There are three new keratoprostheses that may help improve the outlook: the KeraKlear artificial cornea, the Gore synthetic cornea, and the CorNeat KPro. Although several of these devices are still in preclinical trials, they show promise in animal models.
- KeraKlear artificial cornea is a lamellar device that can be implanted in a laser suite. Inserted through a 3.5-mm microincision into a partial thickness corneal pocket made by a femtosecond laser, the device can replace anywhere between 200 and 700 µm of diseased tissue. The presence of posterior corneal pathology limits visual outcomes. The indications for this device include anterior corneal scars and opacities in noninflamed corneas. Data from European trials show that it could mitigate issues with endophthalmitis, retroprosthetic membrane formation, and glaucoma associated with existing devices. The U.S. trial is currently on hold.
- Gore synthetic cornea is a fully synthetic, full-thickness, single-piece device. The fluoroelastomer optic is soft, foldable, and bioinert. The biointegratable skirt is made of expandable polytetrafluoroethylene and is flexible, suturable, and microporous. The device can be inserted using a minimally invasive single-step surgery that does not require device assembly or expensive instrumentation. Preclinical studies with rabbits show promising results at 16 months, with low infection and inflammation rates, and tissue attachment to the optic wall.
- CorNeat KPro is a two-part implant with a PMMA optic. It may have better integration thanks to its external integrating skirt—made by electrospinning carbonated polyurethane fibers—that is implanted under the conjunctiva. It also has access ports to make future intraocular access easier, and it comes with dedicated tools to help with implantation. Studies in rabbits show promise. Three human patients have received the device and have had good results and retention thus far.
Dr. Farid is excited to see how these devices develop and looks forward to their becoming accessible to more surgeons in the future. —Kanaga Rajan, PhD
Financial disclosures: Dr. Farid: Allergan: C; Bausch + Lomb: C; Bio-Tissue, Inc.: C; CorneaGen: C; Dompe: C; Johnson & Johnson Vision: C; KALA: C; Novartis, Alcon Pharmaceuticals: C; Sun Ophthalmics: C; Tarsus: C; Zeiss: C.
Disclosure key. C = Consultant/Advisor; E = Employee; L = Lecture Fees; O = Equity Owner; P = Patents/Royalty; S = Grant Support.