A look at the latest developments in corneal preservation and donation.
There are certain human tissues that can be extracted and stored for future use — for example, cord blood, eggs and sperm. With a newly introduced service, it is now possible to freeze your own corneal tissue and use it to treat presbyopia or other eye conditions that you may develop later in life.
(SMILE) is a type of refractive eye surgery (similar to
LASIK), which reduces patients’ dependency on glasses for distance vision. During this surgery, a laser cuts a tiny disc-shaped piece of corneal tissue called the corneal lenticule, which is then removed via a keyhole incision.
The corneal lenticule is usually thrown away after the procedure. However, the tissue has potential for other uses as it is shaped like a lens with a specific power. A lenticule with 300 degrees of myopia will be like a lens with a corrective power of 300 degrees.
Patients typically develop presbyopia (the loss of ability to focus on near objects) in their 40s, and require reading glasses or plastic implants to correct their vision. Clin Prof Donald Tan, Visiting Senior Consultant of SNEC’s
Corneal & External Eye Disease Department, said that if a patient’s own lenticule were to be re-implanted, it can correct this eye condition with minimal risk of inflammation, scarring or rejection.
To establish a long-term storage facility for corneal lenticules, Clin Prof Tan and
Prof Jodhbir Mehta, Head and Senior Consultant at SNEC’s
Corneal & External Eye Disease Department, worked with local company Cordlife Group, which owns various international cord blood banks, to develop OptiQ.
The first in the world to offer such a service, OptiQ was officially licensed by the Ministry of Health in January 2021 and launched on 3 March 2021. Cordlife’s facility has the capacity to store the lenticules below -150°C. Corneal lenticules may be able to treat not only presbyopia, but also other conditions such as hyperopia, aphakia, and corneal perforation. Although the use of lenticules in treatment is still being trialled, the key is in preventing wastage of tissue by storing it for potential future use.
“Almost every one of us will have presbyopia after the age of 40. We believe this advancement in ophthalmology can help a lot of people, and take healthcare in Singapore to the next level,”said Prof Mehta.
OFFER THE GIFT OF SIGHT
The cornea is the transparent, protective tissue that covers the front part of the eye, and helps the eye to focus light and see clearly. An infection, eye injury, congenital condition or age-related degenerative eye disease can result in a cloudy cornea, leading to poor vision or even blindness. But as long as the nerve and retina at the back of the eye are still healthy, patients can benefit from a corneal transplant.
A corneal transplant involves replacing the diseased cornea with a healthy cornea from a donor. The procedure has the potential to fully restore vision.
Nearly 500 corneal transplants are performed in Singapore every year. However, the number of donors has been declining in recent years, with donations falling to a five-year low of 141 in 2019, according to
Clin Assoc Prof Anshu Arundhati, Senior Consultant at SNEC’s Corneal & External Eye Disease Department, and Clinical Director at
Singapore Eye Bank.
Despite the support from reputable US eye banks, there is still an urgent need to strengthen the local supply of donated corneas as the overseas supply can be disrupted at any time, especially during a pandemic.
While there is no existing man-made alternative for a human cornea,
SERI are currently developing tissue-engineered constructs. If successful, a pair of donor corneas can create up to 80 constructs and potentially alleviate any shortfall in the future.
About cornea donation
Blood type, age, eyesight and eye colour are not factors for cornea donation. However, corneas of individuals who had communicable diseases, certain cancers and neurological conditions, eye diseases, and other illnesses that may compromise the safety and quality of the tissue will not be accepted.
Cornea removal is usually performed shortly after a donor’s death. The eyeball is kept intact during the process, with the body of the deceased treated with utmost respect. It will not result in any form of disfigurement, and an open-casket funeral service can proceed.
In Singapore, the Human Organ Transplant Act (HOTA) allows for the kidneys, heart, liver and corneas to be removed — for the purpose of transplantation — in the event of death from any cause. HOTA covers all Singapore Citizens and Permanent Residents aged 21 years and above who do not have mental disorders, unless they have opted out of the scheme.
Find out more about cornea donation at:
here to check out other articles in SINGVISION Issue 1/2021.
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