There is a chronic undersupply of corneal tissue worldwide. It’s estimated that there is only one donor cornea for every 70 diseased eyes that would benefit from transplant surgery.1 Estimates show there are up to 30 million patients around the world in need of corneal restoration.1 Luckily, recent advances in corneal surgery are helping to ease these shortages and hopefully will aid in streamlining the surgical process.
Every year, hundreds of corneas donated to eye banks are disqualified from being used due to deferral policies by FDA and the Eye Bank Association of America, mostly out of concern for potential disease transmission.2
This month, I’d like to highlight new trials that could address the worldwide shortage of corneal tissue needed for restoration. Partial-thickness procedures should benefit from the advances that allow one donor to be used for multiple patients.1,2 In addition, new harvesting techniques for corneal surface limbal stem cell–deficient patients can show fabulous results, and artificial corneas appear to be a viable reality.
The IOTA study is looking at using an injectable corneal endothelial cell therapy.1 The overarching goal is to treat more patients with fewer corneas and may ultimately be the preferred procedure for all corneal endothelial disease. In an earlier phase, two donor corneas treated 50 patients with endothelial disease.1 Patients experienced both an improvement in acuity and a decrease in corneal thickness. Equally exciting, this cell therapy is easily accessible to surgeons, minimally invasive for patients and is less complicated than doing posterior lamellar surgery.1
A new polymer film (synthetic endothelial layer) that acts as a barrier preventing excess fluid from entering the cornea is being investigated. EndoArt (EyeYon Medical) provides a minimally invasive procedure to reduce and prevent corneal edema.3
Several investigators have found a way to harvest tissue to be used in patients with limbal stem cell deficiency.4,5 Recently, methods of stem cell transplantation use ex vivo cells. Limbal tissue can come from a relative, cadaver or the normal fellow eye and expanded in culture before grafting. Cell farming using limbal- derived mesenchymal produces collagen for biosynthetic corneas, and adipose mesenchymal with liquid cornea for clinical application may be an alternative used in the future.5
New technologies include pluripotent stem cell use, seeding stem cells on amniotic membrane transplantation and using plasma-coated lenses or other alternate scaffolds for in vivo culture and transfer of transplanted cells.4,5 SMILE lenticules treated with recipient donor human induced pluripotent stem cells have been attempted as well.5
A New Artificial Cornea
The AlphaCor, a synthetic polymer, has addressed some of the complications (glaucoma, extrusion, endophthalmitis and membrane formation) of first-generation keratoprosthetic devices. AlphaCor was the first keratoprosthesis to obtain FDA approval nearly 20 years ago, but this device often results in stromal melting and optics degradation over time.3
An Israeli company, CorNeat Vision, has developed a new artificial cornea (CorNeat KPro) that has already been successfully implanted in several patients around the world. The device—a synthetic, non-degradable nanofibric skirt—is designed to integrate with ocular tissue (under the conjunctiva). This device takes advantage of bio-integrating with the highly vascularized and fibroblast-rich conjunctival tissue.3 It seems to provide immediate visual performance, doesn’t require donor tissue and can’t transmit disease.
Corneal regeneration procedures with advanced harvesting techniques and artificial devices will continue to improve. We look forward to the day when no patient in need of restorative corneal surgery goes without a viable procedure. In the meantime, perhaps another look at donor tissue disqualification by our regulatory agencies is in order.
1. Aurion Biotech announces IOTA cell therapy trials. aurionbiotech.com/aurion-biotech-announces-iota-cell-therapy-trial-2. July 25, 2021. Accessed April 19, 2022.
2. Linnehan R. FDA policy turns away thousands of potential cornea donations each year. Association for Research and Ophthalmology. www.healio.com/news/ophthalmology/20200529/fda-policy-turns-away-thousands-of-potential-cornea-donations-each-year. May 29, 2020. Accessed April 19, 2022.
3. Holland G, Pandit A, Sanchez-Abella L, et al. artificial cornea: past, current and future directions. Front Med (Lausanne). 2021;8:770780.
4. Le-Bel G, Guerin LP, Carrier P et al. Grafting of an autologous tissue-engineered human corneal epithelium to a patient with limbal stem cell deficiency (LSCD). Am J Ophthalmol. 2019;15:100532.
5. Karakus S. Limbal stem cell deficiency. EyeWiki. eyewiki.aao.org/limbal_stem_cell_deficiency. July 30, 2021. Accessed April 19, 2022.