Delivering Endothelial Keratoplasty Grafts: Modern Day Transplant Devices

Abstract

For over a decade, endothelial keratoplasty (EK) has been popularized as a standard of care for treating endothelial dysfunction. 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 patients. In addition, due to limited availability of healthy cadaveric donor corneas required for such transplants, it becomes extremely important to reduce any potential wastage and optimize the use of every donor cornea. 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. The review thus aims to summarize and compare the popular devices that have been used for delivering EK grafts in recent times.

DMEK graft: One size does not fit all

“…Although pre‐loaded DMEK with endothelium outwards seems like a viable option with small sized grafts, it is equally challenging in terms of preparing the pre‐loaded DMEK grafts with endothelium inwards. However, new devices such as DMEK Rapid and Coronet DMEK EndoGlide may be adopted for smaller grafts (Ighani et al, 2021; Parekh et al, 2022a,b; Wojcik et al, 2021).…”

“…Graft detachment, re‐bubbling, postoperative ECL, complications and rejections can be multifactorial (Parekh et al, 2018a,b) and centre‐centric (Parekh et al, 2022a,b). However, graft size to descemetorhexis is one of the crucial parameters to be considered before performing EK.…”

“…In case of ‘endo‐in’, in order to preserve the architecture of the graft as ‘taco fold’, an injector is preferred (standard intra‐ocular lens [IOL] cartridge), which may require an incision of 2.2–3.0 mm. This technique has shown a 6‐month ECL of about 30% with the Viscojet 2.2 IOL Cartridge (Medicel AG, Wolfhalden, Switzerland) (Busin et al, 2016; Busin et al, 2018; Parekh et al, 2022a,b; Price et al, 2018a,b). Instead, in case of ‘endo‐out’, the Straiko modified Jones tube has been used with reported ECL at 6 months of approximately 30% (Newman et al, 2018; Parekh et al, 2022a,b).…”

“…The correct delivery and implantation of donor graft in the anterior chamber of the host is important to reduce possible damage to the tissue (Dapena et al, 2009). Reported implantation technique of DMEK grafts according to the orientation of the endothelium include endothelium‐inward (endo‐in) or endothelium‐outward (endo‐out) (Parekh et al, 2017a,b; Parekh et al, 2022a,b; Price et al, 2018a,b). These two techniques do not differ in rate of ECL after implant, which, at 6 months, has been reported between 29.5% and 30.9% (Busin et al, 2018; Newman et al, 2018; Price et al, 2018a,b).…”

“…However, other marking strategies proposed by Bala (2020), Tzamalis et al (2020) or Muraine et al (2013) suggest that trephines could be ideal to avoid additional cell loss. Preloaded DMEK with endo‐in (DM‐endothelium complex manually tri‐folded like a ‘taco’ with endothelium facing inwards) (Figure 3a) can be challenging with small graft sizes (Busin et al, 2018; Parekh et al, 2017a,b; Parekh et al, 2022a,b). Small diameter graft does not have enough area to be manually folded and maintain the tissue architecture in the preservation/transplantation device hence, specialized devices need to be designed.…”