Clear tectonic penetrating graft using glycerine-preserved donor cornea

Clinical outcomes of long-term corneas preserved frozen in Eusol-C used in emergency tectonic grafts

To report the clinical results on the use of corneas frozen in Eusol-C as tectonic corneal grafts.Retrospective review of medical records of patients who received frozen corneas as emergency tectonic grafts from 2013 to 2020. Corneas had been stored in Eusol-C preservation media at − 78 °C for a mean time of 6.9 months. Diagnosis, transplant characteristics, microbial culture results, anatomic integrity, epithelial healing, neovascularization, transparency, infection and need for additional surgeries were registered. Fifty corneas were used in 40 patients (mean age 60.5 years, 20 males) with a median follow-up of 27.3 months after surgery. Need for tectonic graft was due to: perforation secondary to immune diseases (6, 12%), neurotrophic ulcer (11, 22%), trauma (3, 6%), corneal infection (11, 22%), chronic disorders of the ocular surface (9, 18%) and previous corneal graft failure (10, 22%). Mean size of grafts was 5.6 mm and 36 cases (72%) also received an amniotic membrane graft. Thirty-eight corneas achieved epithelization (76%), 25 (50%) were clear and 19 (38%) developed neovascularization. None of the corneas were rejected. Seventeen corneas (34%) failed: 7 (14%) due to reactivation of baseline disease and 10 (20%) due to primary graft failure. Four corneas (8%) had positive microbial cultures suggestive of contamination and 2 (4%) developed a cornea abscess non-related to a positive microbial culture. Long-term preservation of donor corneas in Eusol-C at − 78 °C is a viable technique to meet the needs of emergency grafts with minimal equipment.

A review of long-term corneal preservation techniques: Relevance and renewed interests in the COVID-19 era

The growth of eye banking in India was showing positive trends until the nation was hit by unprecedented times as a result of the COVID-19 pandemic. The impact of this has led to a downward spiraling in eye banking activities globally. Several measures had to be implemented to tide over the crisis and strategies planned for future to prepare for the needs of corneal transplantation. While eye banks in India have been practicing short- term and intermediate storage preservation media, there is a definite need to evolve other methods of very long-term preservation. This review discusses various methods of long term corneal preservation, their relevance and applications in the present times. We reviewed relevant medical literature in English from PUBMED with the key words “Corneal preservation”, “Cryopreservation”, “Glycerol preservation”, Gamma Irradiation”, “Eye Banking” ,”COVID-19”.

In-body tissue-engineered collagenous connective tissue membranes (BIOSHEETs) for potential corneal stromal substitution

There is a severe shortage of donor cornea for transplantation in many countries. Collagenous connective tissue membranes, named BIOSHEETs, grown in vivo were successfully implanted in rabbit corneal stroma for in vivo evaluation of their suitability as a corneal stromal substitute to solve this global donor shortage. BIOSHEETs were prepared by embedding silicone moulds into dorsal subcutaneous pouches in rabbits for 1 month and stored in glycerol. After re-swelling in saline and trephining, disk-shaped BIOSHEETs (4 mm diameter) were allogeneically implanted into stromal pockets prepared in the right cornea of seven rabbits. Clinical tests for corneal thickness and transparency, and tissue analyses were performed. Because the BIOSHEETs (thickness, 131 ± 14 µm) obtained were opaque immediately after implantation, the transparency of the cornea decreased. The total thickness of the BIOSHEET-implanted cornea increased from 364 ± 21.0 µm to 726 ± 131 µm. After 4 weeks' implantation, the thickness of the cornea stabilized (493 ± 80 µm at 4 weeks and 447 ± 46 µm at 8 weeks). The transparency of the cornea increased progressively with time of implantation. The random orientation of collagen fibrils in the original BIOSHEETs tended to be homogeneous, similar to that of the native stroma. No inflammatory cells accumulated and fibroblast-like cells infiltrated the implant. The BIOSHEETs showed high biocompatibility with stromal tissues; however, further studies are needed to test its functional aspects. Although this research is only intended as a proof of concept, BIOSHEETs may be considered a feasible corneal stromal replacement, especially for treating visual impairment caused by stromal haze. Copyright © 2013 John Wiley & Sons, Ltd.

The use of glycerol-preserved corneas in the developing world

Corneal opacity is the third leading cause of blindness in the developing world and encompasses a wide variety of infectious, inflammatory and degenerative eye diseases. Most caes of corneal blindness are treatable with partial or full-thickness keratoplasty, provided adequate corneal tissue and surgical skill is available. However, access to sightrestoring keratoplasty in developing countries is limited by the lack of developed eye banking networks and a critical shortage of tissue suitable for transplantation. Beyond the developed world, corneal transplantation using fresh corneal tissue (FCT) is further hindered by unreliable storage and transportation facilities, unorganized distribution networks, the cost-prohibitive nature of imported tissue, unreliable compliance with medications and follow-up instructions and inadequate health and education services. Glycerol-preserved corneas overcome many of these limitations inherent to the use of FCT. As surgical innovation in lamellar corneal surgery expands the potential use of acellular corneal tissue, long-term preservation techniques are being revisited as a way to increase availability of corneal tissue to corneal surgeons throughout the developing world. Herein, we discuss the advantages of using and the applications for glycerol-preserved corneal tissue throughout the developing world.