"Ray of light during tough times"-Role of gamma irradiated corneal tissue in emergency keratoplasty.

Dear Editor:

The COVID-19 pandemic shook the entire world with its rapid spread and high mortality rate. Blindness due to untreated corneal emergencies is an underappreciated area of COVID's impact on eye care. The consequences of lockdown were mostly negative on patient care. Cessation of eye banking services across India on March 24, 2020 was one of the lockdown measures, and resulted in significant difficulty in the management of patients presenting with infectious keratitis or severe trauma. Because of unavailability of donor grafts, the surgical intervention with corneal transplantation to treat severe/advanced corneal ulcers with frank or impending perforations became impossible. As corneal surgeons, we are unfortunately witnessing a slow and painful death of the eye.

Eye Bank Association of India has come up with a hopeful yet stringent order to resume eye banking services in areas that are considered COVID-free, with adequate precautions.[12] However, major eye banks in India with maximum eye donations are stalled by the fact that they all are located in the red zones and hot spot areas. Although India is still yet to reach its first peak, Leung and colleagues[3] have predicted a second wave in their modeling impact assessment, indicating the possibility of darker days ahead. So, what is the potential ray of light at the end of the tunnel in this bleak moment of despair? It is time for us to brainstorm on innovative techniques to preserve available grafts to ease storage requirements and extend their utility.

Gamma irradiation of corneal tissue is an alternative technique for long-term preservation of donor corneal lenticules. It was first introduced by Tissue Bank International, Baltimore, Maryland, USA, in 2009. Tissues that are not suitable for optical keratoplasty but with clear stroma undergo sterilization by a validated gamma irradiation process.[4] Once terminally sterile, the tissue is stored in albumin that has a shelf life of 2 years at room temperature. The end product is a compact sterile cornea with clear stroma but no viable epithelium or endothelium that is ready for use at any time, for elective or emergency procedures. Compared to the other long-term storage media such as glycerin that make the tissue thick, rubbery, and hazy, this method offers an easy handling for the surgeon, similar to using a fresh corneal tissue, in addition to clarity. The tissue can be used as partial thickness anterior patch to remedy a perforation or impending perforation or as a full thickness keratoplasty to treat severe intractable infection. In addition to instant availability, a major advantage is its reduced allogenicity due to irradiation and lack of sensitization, which in turn can decrease the risk of allograft rejection thereby increasing the subsequent success of future optical keratoplasty.[5] Most of the published studies in Western literature are on its usage for anterior lamellar keratoplasty and full thickness usage with Boston type 1 keratoprosthesis. Interestingly, its use has been maximized in glaucoma surgeries for patch grafts. In developing countries like ours, where the incidence of infectious keratitis or trauma requiring emergency tectonic keratoplasty is very high, the promise offered by gamma-irradiated graft for a stopgap treatment is profound. The justification to have access to gamma irradiation to enhance the storage of available donor corneal grafts during these difficult times is heightened. It would be a great start to explore alternative options like gamma-irradiated corneal lenticules as we might step into more difficult times ahead. Beyond the COVID pandemic, this could also be a boon for tackling corneal blindness in places where ophthalmologists don't have access to eye banks or fresh corneal grafts.

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