Case report: Favipiravir-induced bluish corneal discoloration in infant with COVID-19.

This report describes a case of a male infant diagnosed with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection who was prescribed favipiravir therapy. The mother noticed a discoloration of the child's eyes within 18 h of therapy, and the cornea returned to normal color within 5 days of medication cessation. This case report highlights the need for monitoring of favipiravir therapy in children due to the potential side effect of corneal discoloration, which has not yet had its long-term effects identified.

DMEK graft: One size does not fit all.

Descemet membrane endothelial keratoplasty (DMEK) is a popular procedure for the treatment of corneal endothelial diseases mainly targeting Fuchs endothelial corneal dystrophy (FECD) and pseudophakic bullous keratopathy (PBK). Although DMEK has multiple advantages, it is challenging in terms of graft preparation and delivery. One of the crucial factors of DMEK graft preparation is determining the size of the graft. Evaluating risks and benefits of transplanting larger or smaller grafts compared with the descemetorhexis performed following a standard DMEK procedure thus becomes important. Advanced techniques like pre-loaded DMEK requires pre-selection of graft diameter without physical examination of the eye making it more challenging. Therefore, recognizing the benefits of graft size and the number of transplanted endothelial cells becomes essential. Smaller DMEK grafts have been preferred and accepted for grafting. Larger diameter grafts have advantages but can be challenging due to higher detachment rates. We thus aim to review the challenges of preparing and delivering DMEK tissues with small or large diameter based on selected descemetorhexis area, discuss the outcomes based on different graft sizes, highlight related complications and suggest which cases may benefit from adopting smaller or larger graft size.

Alternatives to endokeratoplasty: an attempt towards reducing global demand of human donor corneas.

The cornea is an anterior transparent tissue of the eye that enables the transmission of surrounding light to the back of the eye, which is essential for maintaining clear vision. Corneal endothelial diseases can lead to partial or total blindness; hence, surgical replacement of the diseased corneal tissue with a healthy cadaveric donor graft becomes necessary when the endothelium is damaged. Keratoplasties face a huge challenge due to a worldwide shortage in the supply of human donor corneas. Hence, alternative solutions such as cell or tissue engineering-based therapies have been investigated for reducing the global demand of donor corneas. This review aims at highlighting studies that have been successful at replacing partial or total endothelial keratoplasty.

The cornea is an important tissue, as it allows the transmission of surrounding light to the back of the eye. The posterior layer of the cornea is made up of hexagonal endothelial cells that help maintaining the required transparency. Corneal endothelial cells do not have a natural regenerative capacity; therefore, if damaged, they must be replaced by healthy donor tissue. It is difficult to obtain human donor corneas; hence, researchers have attempted to grow endothelial cells using specific drugs that allow these cells to grow in the lab. In this review, we highlight the application of lab-grown cells in animal and human studies with ongoing clinical trials of other drugs and techniques to replace the need of human donor tissues.

Delivering Endothelial Keratoplasty Grafts: Modern Day Transplant Devices.

PURPOSE: To summarize the graft loading, transporting and delivery devices used for endothelial keratoplasty (EK). METHODS: A literature search of electronic databases was performed. RESULTS: New techniques and devices have been introduced and implemented to prepare, load, transport and transplant the grafts for EK. The advantages are not only limited to the surgical theatre but also widely spread across the eye banking field. Investigation of advanced materials and designs have been rapidly growing with continuous evolution in the field of eye banking and corneal transplantation. Innovative techniques and modern devices have been evaluated to reduce the endothelial cell loss and increase the precision of the transplant in order to benefit both surgeons and the patients. CONCLUSIONS: It is extremely important to reduce any potential wastage and optimize the use of every available donor cornea due to the limited availability of healthy cadaveric donor corneas required for transplants. As a result, the use of pre-cut and pre-loaded grafts supplied by the eye banks in calibrated devices have been gaining momentum. Innovation in the field of bioengineering for the development of new devices that facilitate excellent clinical outcomes along with reduction in learning curve has shown promising results.

Challenges in corneal endothelial cell culture.

Corneal endothelial cells (CECs) facilitate the function of maintaining the transparency of the cornea. Damage or dysfunction of CECs can lead to blindness, and the primary treatment is corneal transplantation. However, the shortage of cornea donors is a significant problem worldwide. Thus, cultured CEC therapy has been proposed and found to be a promising approach to overcome the lack of tissue supply. Unfortunately, CECs in humans rarely proliferate in vivo and, therefore, can be extremely challenging to culture in vitro. Several promising cell isolation and culture techniques have been proposed. Multiple factors affecting the success of cell expansion including donor characteristics, preservation and isolation methods, plating density, media preparation, transdifferentiation and biomarkers have been evaluated. However, there is no consensus on standard technique for CEC culture. This review aimed to determine the challenges and investigate potential options that would facilitate the standardization of CEC culture for research and therapeutic application.

Biomaterials for corneal endothelial cell culture and tissue engineering.

The corneal endothelium is the posterior monolayer of cells that are responsible for maintaining overall transparency of the avascular corneal tissue via pump function. These cells are non-regenerative in vivo and therefore, approximately 40% of corneal transplants undertaken worldwide are a result of damage or dysfunction of endothelial cells. The number of available corneal donor tissues is limited worldwide, hence, cultivation of human corneal endothelial cells (hCECs) in vitro has been attempted in order to produce tissue engineered corneal endothelial grafts. Researchers have attempted to recreate the current gold standard treatment of replacing the endothelial layer with accompanying Descemet's membrane or a small portion of stroma as support with tissue engineering strategies using various substrates of both biologically derived and synthetic origin. Here we review the potential biomaterials that are currently in development to support the transplantation of a cultured monolayer of hCECs.