Clinical evaluation of a newly developed graft inserter (NS Endo-Inserter) for Descemet stripping automated endothelial keratoplasty

The progress and future of corneal endothelial transplantation

Endothelial transplantation has recently been accepted worldwide, in the long history of corneal transplantation. The introduction of endothelial keratoplasty (Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty) has enabled us to expand the surgical indications owing to the low incidence of rejection and quick recovery of visual function. New technologies have been developed to ensure stable postoperative outcomes with a shorter learning curve, such as transplantation using cultured human endothelial cells and induced pluripotent stem cells (iPS) or new devices such as artificial endothelium. This review discusses the history and characteristics of corneal transplantation alongside new treatment options that may offer hope for patients with endothelial disease in the future.

Descemet stripping automated endothelial keratoplasty via a frown incision

PURPOSE

To assess the outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK) via a sclerocorneal frown incision.

STUDY DESIGN

Retrospective comparative study.

METHODS

The outcomes of Descement stripping endothelial keratoplasty (DSAEK) were retrospectively compared between 36 patients (36 eyes) who underwent surgery via a 3.8-mm frown incision (frown incision group) and 20 patients (20 eyes) who underwent surgery via a 4.6-mm straight incision (straight incision group). In all patients, an NS Endo-Inserter was used as the graft inserter and the incision for a frown incision was via the superior sclerocorneal site and for the straight incision via the temporal cornea. DSAEK was performed by the standard technique, except for the incision. At 1 year after surgery, the two groups were compared with respect to the visual acuity, decrease of corneal endothelial cell density, the severity of corneal astigmatism (diopters), the number of sutures for wound closure, and intraoperative/postoperative complications.

RESULTS

There was no significant difference between the two groups in terms of postoperative visual acuity, corneal astigmatism, and intraoperative/postoperative complications one year after surgery. On the other hand, the number of sutures required for wound closure was 1.13 ± 0.42 in the frown incision group, whereas in the straight incision group, it was 3.20 ± 0.40, showing a significant difference (P<0.001). In addition, there was no decreased corneal endothelial cell density associated with the reduction in incision width.

CONCLUSIONS

A sclerocorneal frown incision is useful for performing DSAEK with an NS Endo-Inserter as it does not affect endothelial cell loss despite its short incision width.

Clinical Outcomes of the Intraocular Lens Injector and Busin Glide for Descemet Stripping Automated Endothelial Keratoplasty in Patients with Iridocorneal Endothelial Syndrome

Purpose: To report the outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK) performed in iridocorneal endothelial (ICE) syndrome patients using the intraocular lens injector (injector), in comparison with those using the Busin glide. Methods: In this retrospective, interventional comparative study, we evaluated the outcomes of DSAEK performed using the injector (n = 12) or the Busin glide (n = 12) for patients with ICE syndrome. Their graft position and postoperative complications were recorded. Their best-corrected visual acuity (BCVA) and endothelial cell loss (ECL) were monitored over a 12-month follow-up period. Results: DSAEK was conducted successfully in the 24 cases. The BCVA improved from the preoperative 0.99 ± 0.61 to 0.36 ± 0.35 at 12 months after operation (p < 0.001), with no significant difference between the two groups (the injector group and the Busin group) (p = 0.933). ECL at 1 month after DSAEK was 21.80 ± 15.01% in the injector group, which was significantly lower than 33.69 ± 9.75% of the Busin group (p = 0.031). No surgery-related complications were observed in the 24 cases intraoperatively or postoperatively except that one case suffered from postoperative graft dislocation, without statistical difference between the two groups. Conclusions: At 1 month after surgery, the use of graft injector for delivering DSAEK-based endothelial graft may cause significantly less endothelial cell damage than the pull-through technique used in the application of Busin glide. The injector allows safe endothelial graft delivery without the need of anterior chamber irrigation, which increases the ratio of successful graft attachment.

Current development of alternative treatments for endothelial decompensation: Cell-based therapy

Current treatment for corneal endothelial dysfunction consists in the replacement of corneal endothelium by keratoplasty. Owing to the scarcity of donor corneas and the increasing number of transplants, alternative treatments such as cell-based therapies are necessary. In this article, we highlight the biological aspects of the cornea and the corneal endothelium, as well as the context that surrounds the need for new alternatives to conventional keratoplasty. We then review some of those experimental treatments in more detail, focusing on the development of the in vitro and preclinical phases of two cell-based therapies: tissue-engineered endothelial keratoplasty (TE-EK) and cell injection. In the case of TE-EK graft construction, we analyse the current progress, considering all the requirements it must meet in order to be functional. Moreover, we discuss the inherent drawbacks of endothelial keratoplasties, which TE-EK grafts should overcome in order to make surgical intervention easier and to improve the outcomes of current endothelial keratoplasties. Finally, we analyse the development of preclinical trials and their limitations in terms of performing an optimal functional evaluation of cell-based therapy, and we conclude by discussing early clinical trials in humans.

Clinical Evaluation of the "Lifeline Suture" Technique for DSAEK in Cases Without Posterior Capsule Using a Novel Donor Insertion Device

PURPOSE

This study investigated preliminary clinical outcomes of a suture pull-through technique for Descemet stripping automated endothelial keratoplasty (DSAEK) termed the "lifeline suture" technique using a newly developed donor inserter (NS Endo-Inserter: NSI; Hoya Co, Ltd, Tokyo, Japan) in cases of bullous keratopathy without posterior capsule.

METHODS

Six aphakic eyes without posterior capsule from 6 patients (mean age 73.8 ± 11.9 years) with bullous keratopathy were enrolled. DSAEK alone or as a vitreocorneal surgery was performed. Donor tissue was pulled into the anterior chamber using the NSI and a 9-0 polypropylene "lifeline suture" to prevent donor tissue from slipping into the vitreous cavity, which was removed at the end of surgery. Intraoperative and postoperative complications and 6-month postoperative central donor endothelial cell densities were measured and compared with preoperative values along with 6-month best-corrected visual acuity.

RESULTS

All donors were successfully loaded into the NSI and then pulled into the anterior chamber using the lifeline suture. No intraoperative complications, graft dislocation, or primary graft failures were noted. Six months postsurgery, mean endothelial cell density was 2027 ± 747 cells/mm (mean loss 27.2 ± 28.1%) and mean best-corrected visual acuity improved to 0.31 decimal (P = 0.018).

CONCLUSIONS

In this preliminary case series of bullous keratopathy without posterior capsule, DSAEK outcomes using the novel NSI donor inserter with lifeline suture were comparable or better than the results expected with conventional strategies. Thus, this technique enabled apparently safe DSAEK, preventing donor migration into the vitreous cavity while maintaining a stable anterior chamber, and is suitable for complex eyes including aphakia, lacking posterior capsule, or avitreal.

NS Endo-Inserter: A New Graft Inserter for Descemet Stripping Automated Endothelial Keratoplasty

Although Descemet stripping automated endothelial keratoplasty (DSAEK) has become widespread as a first choice for the treatment of bullous keratopathy, corneal endothelial cell loss during the early postoperative period caused by intraoperative mechanical stress to the donor endothelium remains a clinical challenge. At present, a pull-through technique is the standard procedure for graft delivery in DSAEK. However, the anterior chamber is likely to collapse during graft delivery in patients with a small eye or shallow anterior chamber, as often seen in Asian patients, leading to endothelial cell damage. To solve this problem, we developed a new device for DSAEK, known as NS Endo-Inserter, in which the graft flows into the anterior chamber in a balanced salt solution in one step. This article reviews the features of NS Endo-Inserter and the outcomes of DSAEK using this device.

Clinical Evaluation of the NS Endo-Inserter, a Novel Donor Inserter for Descemet's Stripping Automated Endothelial Keratoplasty

Purpose

This study investigated the clinical outcomes achieved with a newly developed donor inserter (NS Endo-Inserter [NSI], HOYA Co., Ltd., Tokyo, Japan) for Descemet's stripping automated endothelial keratoplasty (DSAEK) in Japanese eyes with bullous keratopathy secondary to argon laser iridotomy (BK-ALI). The NSI device utilizes pressure flow to push the DSAEK donor tissue into the anterior chamber.

Methods

Six eyes of 6 patients (1 male, 5 females; mean age, 78.5 years) with BK-ALI were enrolled. Donor tissue was pushed into the anterior chamber using the NSI. Intraoperative complications, graft dislocation, and iatrogenic primary graft failure were recorded for all eyes. Six-month postoperative central donor endothelial cell densities (ECD) were measured prospectively and compared with preoperative values, along with 6-month best corrected visual acuity (BCVA).

Results

In all cases, donor loading onto the NSI spatula and donor insertion into the anterior chamber using the NSI was smooth and successful; no intraoperative complications were noted. There were no cases of graft dislocation or IPGF. Postoperative ECD was 2,187.2 cells/mm² (mean loss, 14.8%) and mean BCVA increased from 0.27 decimal to 0.8 at 6 months.

Conclusion

In this small preliminary case series, clinical outcomes for patients with BK-ALI undergoing DSAEK using the NSI were comparable or better than those achieved with conventional DSAEK insertion techniques.