The cornea, the clear covering on the front of the eye or “the window of the eye”, is responsible for refracting light and directing it to the retina. A diseased or damaged cornea leads to vision loss or blindness.  

Corneal scarring from infections or trauma is a leading cause of reversible blindness in both children and adults. https://pmc.ncbi.nlm.nih.gov/articles/PMC3831688/ Symptoms from mild scarring (inflammation and discomfort) can be managed by corticosteroid and lubricating eye drops. https://eyeinstitute.com/corneal-scarring-treatment-methods-and-recovery-options Laser surgery (phototherapeutic keratectomy or PTK) can minimize scars. https://eyeinstitute.com/corneal-scarring-treatment-methods-and-recovery-options Scleral lenses (rigid and protective contact lenses) can postpone or remove the need for surgical intervention. https://eyeinstitute.com/corneal-scarring-treatment-methods-and-recovery-options In severe causes of scarring, however, a transplant may be necessary. 

What is a Corneal Transplant? 

When corneal scarring is severe, corneal blindness can be avoided or reversed with a corneal transplantation, one of the most successful tissue transplant procedures. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/corneal-transplantation The faulty cornea is replaced with a healthy donor cornea, either in whole or in part. “We replace as little of the cornea as is possible because the procedure is less invasive and it is better. It means faster healing,” notes Dr. Audrey Rostov, a long-time volunteer ophthalmologist of Cure Blindness Project, who focuses on cornea, cataract and refractive surgery.“ 

Depending on the damage to the cornea, a surgeon may need to repair one or more layers. A cornea has six layers total. A transplant involving all six layers of the cornea is called a penetrating keratoplasty (PK). There are two types of a PK, namely Optical and Therapeutic Keratoplasty. On the other hand, if only the inner layer of cells has disease or damage, the surgeon performs a partial thickness corneal transplant, known as an Endothelial Keratoplasty. Two types are Descemet Stripping Endothelial Keratoplasty (DSEK) and Descemet Membrane Endothelial Keratoplasty (DMEK).  If only the outer layer of cells has disease or damage, the surgeon performs a Deep Anterior Lamellar Keratoplasty (DALK).  

Corneal Transplants Depend on Donors

Corneal transplants are the most frequent transplants in the world https://jamanetwork.com/journals/jamaophthalmology/fullarticle/2474372 and they depend on the donation of corneal tissue. Eye banks are one part of the infrastructure of a process that also screens donors, recovers tissue and prepares it for transplantation.  

Donated corneal tissue supply does not keep up with the demand: the tissue itself has a shelf-life of seven to 14 days, according to Rostov. A global shortage of donated tissue can be attributed to limited infrastructure (including eye banks) but also to cultural and governmental barriers to organ donation overall. https://eyewiki.org/Corneal_Donation#List_of_Major_International_Eye_Bank_Associations

Rostov points to Ghana as a country working on the shortage, “A huge issue with corneal transplants in Ghana is that it is illegal to have any organ or tissue donated, so there is no eye bank and—obviously—you cannot do the transplant.” She then emphasizes, “They are working on solving this. [Cure Blindness Project and local corneal surgeons] are trying to get this to a committee so it can go to Parliament and create a pathway for eye, organ and tissue donation [in the country of Ghana].” 

Are Eye Transplants and Corneal Transplants the Same?

Eye transplants are not the same as corneal transplants: eye transplant operations replace the entire eye, while corneal transplants replace the cornea of the eye. Corneal transplants rely on corneal donations, which are stored in eye banks. Eye banks accept whole eyes for research and education only. https://restoresight.org/cornea-donation/faqs/ The first successful human corneal transplant was performed by Eduard Zerm in 1905, although recorded attempts had been made since 1838. https://pmc.ncbi.nlm.nih.gov/articles/PMC3872837 The world’s first eye transplant was performed May 27, 2023, by a surgical team led by NYU Langone Health's Eduardo Rodriquez. https://www.sciencealert.com/worlds-first-entire-eye-transplant-declared-a-medical-breakthrough To date, full eye transplants are not a mainstream medical procedure.

What Causes Someone to Need Corneal Transplants? 

Damage to the cornea may be due to infection, trauma, or disease. When damage to the cornea is extensive and unresponsive to less invasive treatment, a transplant may restore vision.  

Keratitis—be it bacterial, fungal, infectious or noninfectious—can cause corneal scarring or opacity. “When they are seen by a doctor, they have a bad infection and we treat the infection,” explains Rostov. “We know they're going to be left with a scar, and then they can have a cornea transplant to reverse that type of blindness.” 

Traumatic injury can result in the cornea becoming opaque in a condition known as limbal stem cell deficiency. “A chemical injury, a burn, toxic medication, trauma, radiation, thermal burns, or injuries of any kind may destroy the limbal cells,” says Dr. Ashiyana Nariani, Senior Technical Advisor on Ophthalmic Training and Research for Cure Blindness Project. “Those are the cells surrounding the cornea and their whole purpose in life is to allow for ongoing regeneration of clear cells in that window of your eye. Without them, the cornea clouds up.” 

Nariani explains the use of other tissue in healing, “In corneal surgery, we use good amniotic membrane. We use the placental tissue from the maternity wards to help heal the front surface of the eye.” She continues, “It's remarkable how the mother is nurturing us in so many ways. We can place placental tissue from a human mother on top of the cornea to heal a wound.”

In low- and middle-income countries, the leading causes of corneal disease requiring corneal transplant are infection and trauma.

In developed countries, other causes for corneal transplant are likely to be diseases such as keratoconus or Fuchs’ dystrophy. According to Nariani, in low- and middle-income countries, the leading causes of corneal disease requiring corneal transplant are infection and trauma. 

Treating Corneal Damage: The Corneal Ecosystem 

Treating corneal blindness involves “a corneal ecosystem of care”, according to Rostov, with collaboration among practitioners, surgeons, and eye banks.  

The ecosystem provides prevention with mid-level practitioners so that the condition does not escalate to corneal blindness. Rostov of Cure Blindness Project explains what these community healthcare volunteers provide. “These [community health workers] do immunizations, mom care, and baby care and they are already in the communities,” she notes. “They become the village eye care workers once they are also trained in basic cornea and basic eye care.” 

If somebody gets injured in the field, the village volunteers can detect a scratch with a magnifying device and some dye. They can diagnose corneal abrasions and treat it with an eye ointment right away. “These volunteers are able to resolve about 96% of what they see,” Rostov states. 

If the condition does not resolve, the volunteers are trained to send the patients on to the next level, a community eye care center. 

If it is beyond the community eye care center’s scope, the center sends the case to the cornea specialist at a tertiary center. Trained surgeons diagnose and treat corneal blindness, and the access to tissue is where an eye bank comes in.  

Amblyopia: Permanent Corneal Blindness in Children 

Amblyopia is a condition in which children who have any blockages of light to the eye due to cataract or other conditions will still be blind because their eyes have gotten used to that. Prolonged sightlessness early in life means the light is not refracted into the sensory optic nerve to the brain. Since this deficit is permanent, vision screening and proper eye exams for children are crucial in addressing corneal blindness. 

Because of the sensitive neurosensory system of the brain during the formative years of a child’s life, children who are diagnosed and treated at a younger age are more likely to succeed with greater chances at restoring their sight.  

However, if detected later on, those same children, despite receiving the best corneal transplant, may still not be able to see. This condition is known as amblyopia. Nariani emphasizes the need for immediate attention and early diagnosis of eye conditions. “For any child, it is prudent that we diagnose eye conditions fast and treat them quickly and effectively.” 

Corneal Transplants Challenges in Low- and Middle-Income Countries 

Providing corneal transplants in low-and middle-income countries means overcoming several challenges: rural healthcare capacity, cost, shortage of transplant tissue, and difficulties of providing long term care. 

The distribution of doctors in any country is uneven, but in low- and middle-income countries, the disparity is more pronounced. Ophthalmologists are not moving into rural areas. “We have more than a billion people in India with 27 ophthalmologists in a city block in Mumbai,” observes Nariani. “Yet the needs are greatest in rural villages where they lack access to care because no ophthalmologist is taking care of those areas.” 

Rostov noticed the same dynamic in Eritrea. “Eritrea is a country where there [are] only five ophthalmologists who do surgery. Very, very few ophthalmologists actually do surgery and most of them are in Asmara, the capital city.” Rostov was able to train the first three residents in a new corneal residency program in Eritrea in June of 2024 as part of Cure Blindness Project. 

“Distributing that big-city expertise to places in need across sub saharan Africa and Southeast Asia, and mapping that out could be a really amazing strategy to eliminate a large burden of the blindness that we face in the world,” notes Nariani. 

Nariani explains, “We at Cure Blindness Project are identifying those needs on the map and are identifying those experts globally to address the cornea burden of blindness in those areas. Not only that, depending upon the skills set of the local corneal surgeons, we train them on even more advanced and less invasive corneal transplant procedures.  We customize the training we provide based on the regional needs.” 

Cost of care in underdeveloped countries is also a challenge to people in need of corneal transplants. Some but not all hospitals have tiered care or charity care, so people do not see a doctor until their condition is extremely dire.  

Donor tissue shortages also present challenges to eye healthcare and surgical interventions. “An emergency corneal transplant might be required but postponed until we get the corneal tissue needed. Sometimes, the wait is one month, two or even three months,” Nariani notes. 

“Unlike cataract surgery, which requires just weeks of post-op follow-up, corneal transplants require lifelong monitoring. Lack of access to experienced local corneal transplant surgeons who can adequately follow these patients is a barrier to being able to provide more corneal transplants in the world,” explains Nariani.  

She continues, “The root of what we do at Cure Blindness Project is enhancing local capacity and establishing strong corneal surgeons who can not only be trained to operate well, but who are also astute in pre-operative and post-operative care of corneal transplant patients.”  

Cure Blindness Project Provides Corneal Transplants 

Approximately 43 million people in the world are blind. Corneal transplants are crucial surgeries in the global treatment of blindness. Cure Blindness Project, a global non-profit organization, helps to provide corneal transplants to cure treatable or preventable blindness in underserved communities in 30 nations across sub-Saharan Africa, South Asia and South America. 

Cure Blindness Project’s model begins with bringing high quality care to those who need it, and offers corneal transplants through its volunteer ophthalmologists and well-trained local capacity. Approximately 200,000 corneas have been provided through eye bank partnerships in India and Nepal to Cure Blindness Project ophthalmic surgeons. https://d3c4xa94vmylbm.cloudfront.net/images/India_FactSheet_July2024.pdf An estimated 50,000 cases of corneal blindness have been prevented through Cure Blindness Project’s work. https://d3c4xa94vmylbm.cloudfront.net/images/India_FactSheet_July2024.pdf For early detection of eye diseases, including ones that need corneal transplants, Cure Blindness Project has conducted more than 16.5 million eye screenings.  Nariani reports that Cure Blindness Project has provided training to more than 20,000 eye care professionals across 43 low- and middle- income countries, including 644 ophthalmologists.

Rostov, a Cure Blindness Project volunteer ophthalmologist for 15 years, explains how powerful these transformations are, “When we return someone not just to sight, but to being a functional, productive member of their community, we have helped to change communities as well as single lives.”