Single-Pass Microkeratome System for Eye Bank DSAEK Tissue Preparation: Is Stromal Bed Thickness Predictable and Reproducible?

Posterior lamellar keratoplasty: techniques, outcomes, and recent advances

Over the past 2 decades, posterior lamellar keratoplasty (PLK) has emerged as an alternative to penetrating keratoplasty in the treatment of corneal endothelial disorders. The reasons for this trend include the search for a safer procedure to replace diseased endothelium that provides faster and better visual rehabilitation and reduces the need for postoperative care. Different surgical techniques, surgical instruments, devices, and lasers have been introduced to overcome technical difficulties, thus improving clinical outcomes. Yet, surgeons and eye banks must address the complications and limitations that arise during the transition to these new techniques. This review discusses the most significant aspects of the evolution of PLK, including a detailed description of current techniques and the direction of future treatment for corneal endothelial disease with the use of laser-assisted surgery, bioengineered corneas, cell therapy, and new pharmacologic therapy.

Femtosecond laser semi-assisted Descemet stripping endothelial keratoplasty: 2-year outcomes of endothelial cell loss and graft survival

Purpose

To assess 2-year endothelial cell loss and graft survival after femtosecond laser semi-assisted Descemet stripping endothelial keratoplasty (FLS-DSEK).

Methods

In this prospective and noncomparative study carried out at Eye Hospital of Shandong First Medical University, 85 eyes (84 patients) with endothelial dysfunction receiving FLS-DSEK (n=62, 75.9%) or FLS-DSEK combined with phacoemulsification cataract surgery and intraocular lens implantation (n=23, 27.1%) from 2013 through 2016 were included. The graft endothelial cell loss, endothelial graft thickness, visual acuity, and complications after surgery were evaluated.

Results

Thin endothelial grafts were all successfully prepared, with no occurrence of perforation. The rate of endothelial cell loss was 17.4%, 18.8%, 19.9%, and 26.7%, and the central graft thickness was 113±54 μm, 102±40 μm, 101±28 μm, and 96±23 μm at 3, 6, 12, and 24 months, respectively. The median best-corrected visual acuity was 0.4 logMAR (range, 0–2 logMAR) at 24 months, demonstrating a significant difference from that before surgery (2 logMAR; range, 0.2–3 logMAR) (T=187.5, P<.001). Partial graft dislocation was the most common postoperative complication, with an occurrence rate of 14% (n=12), and it was associated with an abnormal iris-lens diaphragm (r=.35, P<.001). The other complications included a high intraocular pressure (n=5, 6%), endothelial graft rejection (n=4, 5%), and pupillary block (n=1, 1%). Endothelial graft decompensation occurred in the two eyes, and 98% (n=83) of the grafts survived at 24 months.

Conclusions

Data of the study suggest that the treatment using FLS-DSEK seems to be promising and might be considered a feasible choice in patients with endothelial dysfunction.

Trial registration

1. Date of registration: 2021-02-18

2. Trial registration number: ChiCTR2100044091

3. Registration site: https://www.chictr.org.cn/

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-021-05383-x.

Single-Pass Mikrokeratome and Anterior Chamber Pressurizer for the Ultrathin Descemet-Stripping Automated Endothelial Keratoplasty Graft Preparation

PURPOSE

To compare the reliability of microkeratome dissection with the anterior chamber pressurizer (ACP) system versus conventional pressurization for ultrathin Descemet-stripping automated endothelial keratoplasty (UT-DSAEK) graft preparation.

METHODS

A retrospective review of a consecutive series of dissected donor corneas processed at Pavia Eye Bank for UT-DSAEK surgery was performed. Grafts were prepared through single-pass microkeratome dissection with artificial anterior chamber internal pressure regulation through either ACP or the conventional method using a water column with tube clamp. The target central graft thickness (CGT) was ≤100 μm. Cutting predictability was determined as the difference between the microkeratome head size and the thickness actually removed. Graft regularity was investigated as central-to-peripheral thickness increase, central-to-peripheral (CP) ratio, and graft thickness uniformity. Thickness was measured with anterior segment optical coherence tomography (horizontal and vertical meridians).

RESULTS

Of the 265 UT-DSAEK grafts, ACP achieved the target "CGT ≤ 100 μm" in 87 of 120 (72.5%), whereas the conventional technique achieved the same in 85 of 145 (58.6%) (P = 0.018). ACP predictability was -3.9 μm (SD: 2.3), whereas predictability of the conventional technique was -54.6 μm (SD: 3.7) (P < 0.001). Thickness increased similarly (P = 0.212); CP ratio was better with ACP for only 2 mm diameter (P = 0.001); graft thickness uniformity was comparable (P > 0.05).

CONCLUSIONS

Compared with conventional pressurization, ACP improved microkeratome-assisted preparation reliability of UT-DSAEK grafts, achieving CGT ≤ 100 μm with significantly higher frequency (P = 0.018) and predictability (P < 0.001). ACP improved CP ratio only at 2 mm (P = 0.001); for other graft thickness, the 2 methods proved equivalent.

Prospective evaluation of clinical outcomes between pre-cut corneal grafts prepared using a manual or automated technique: with one-year follow-up

Purpose

Posterior lamellar corneal surgery is considered the standard of care for irreversible endothelial cell dysfunction. Pre‐cut grafts can be prepared either manually (Descemet stripping endothelial keratoplasty; DSEK) or mechanically (Descemet stripping automated endothelial keratoplasty; DSAEK). We performed a head‐to‐head clinical comparison between DSEK and DSAEK grafts.

Methods

All DSEK and DSAEK procedures performed by two corneal specialists at the University Medical Center Utrecht from 1 January 2016 through 31 October 2016 were prospectively included. Pre‐cut grafts were delivered by two eye banks, which either exclusively prepared the DSEK or DSAEK grafts. Preoperative and postoperative measurements were obtained, and all surgical events and adverse events were recorded.

Results

A total of 21 DSEK and 53 DSAEK procedures were included for analysis; the two groups were similar at baseline, with the exception of graft endothelial cell density, which was 2531 ± 67 versus 2748 ± 148 cells/mm², respectively (p < 0.001). At the one‐year follow‐up visit, corrected distance visual acuity and endothelial cell loss were similar between the groups. Mean pachymetry was significantly lower in the DSEK group (521 ± 39 versus 588 ± 59 μm; p < 0.001), whereas the rebubbling rate was significantly higher in the DSEK group (47.6% versus 18.9%; p = 0.001). Finally, three grafts in the DSEK group experienced failure compared to one graft in the DSAEK group (14% versus 1.9%, respectively).

Conclusion

Manually dissected and microkeratome‐dissected grafts performed similarly with respect to vision and endothelial cell loss assessed one year after surgery. The higher incidence of graft failure among manually dissected (i.e. DSEK) grafts may be attributable to reduced relative thickness compared to DSAEK grafts and/or the resulting differences in tissue handling and the surgeon's learning curve.

Ultrathin Descemet stripping automated endothelial keratoplasty

PURPOSE OF REVIEW

Endothelial keratoplasty has evolved tremendously since its inception. Thick Descemet stripping automated endothelial keratoplasty (DSAEK) grafts have made sway for slimmer ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK). This review discusses the recent literature comparing outcomes of UT-DSAEK, DSAEK, and Descemet membrane endothelial keratoplasty (DMEK).

RECENT FINDINGS

DMEK provides quick visual recovery and has remarkably low incidence of graft rejection. However, the learning curve is long compared to DSAEK. UT-DSAEK utilizes donor grafts less than 100-μm thick. Recent studies comparing DMEK and UT-DSAEK have shown DMEK has better visual outcomes with similar rejection rates.

SUMMARY

UT-DSAEK remains an excellent surgical option for endothelial keratoplasty in eyes with complex anterior segment anatomy. The visual outcomes after UT-DSAEK have been shown to be superior when compared with DSAEK. Recent studies show that DMEK provides better visual outcomes compared with UT-DSAEK.

A Simple 60-Second Swelling Technique for More Consistent Ultrathin DSAEK Graft Preparation

PURPOSE

The purpose of this study is to describe a simple but novel 60-second swelling technique for ultrathin Descemet stripping automated endothelial keratoplasty (DSAEK) graft preparation. In addition, we aim to demonstrate the effectiveness of this technique in obtaining thinner DSAEK grafts more consistently without compromising graft quality.

METHODS

We performed a retrospective case-control study comparing standard DSAEK preparation using an ML7 Microkeratome Donor Cornea System (Med-Logics Inc, Athens, TX) with an additional 60 seconds of stromal swelling with a balanced salt solution after the removal of the epithelium but before the microkeratome pass. Thirty cases using this novel swelling technique were compared with controls matched by age, sex, and precut corneal thickness. Donor characteristics and both precut and postcut graft characteristics were analyzed.

RESULTS

DSAEK grafts prepared with our simple swelling method were approximately 13 μm thinner on average than those prepared with our conventional ultrathin DSAEK preparation technique (P = 0.001). The frequency of grafts less than 100 μm was much greater with swelling (93.3% vs. 63.3% with conventional technique, P = 0.0052). There were no significant differences in postcut cell counts or decrease in cell counts between the groups.

CONCLUSIONS

A simple 60-second swelling technique can yield significantly thinner DSAEK tissue in a more consistent range without a significant impact on the endothelial cell count.

Long-term Clinical Outcome After Descemet Membrane Endothelial Keratoplasty

PURPOSE

To evaluate the long-term clinical outcome up to 5 years after Descemet membrane endothelial keratoplasty (DMEK).

DESIGN

Retrospective, consecutive case series.

METHODS

In this single-center study, 310 consecutive DMEK operations for endothelial decompensation were reviewed; 97 eyes of 84 patients met the inclusion criterion of a minimum 3-year follow-up. Retrospective evaluation of clinical examinations occurred at 1 and 3 months and annually up to 5 years after DMEK at the Department of Ophthalmology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen (FAU), Germany. Main outcome measures were corrected distance visual acuity (CDVA), endothelial cell density (ECD), central corneal thickness (CCT), and graft survival (Kaplan-Meier analysis).

RESULTS

Mean follow-up was 53 ± 13 months. CDVA improved from 0.62 ± 0.42 logMAR before DMEK to 0.13 ± 0.12 logMAR (P < .001); 57% of eyes without ocular comorbidities reached ≥20/25 at 5 years after DMEK. ECD was stable after the initial postsurgical decrease (42% at 1 month, 44% at 5 years), from 2602 ± 243 cells/mm(2) before DMEK to 1460 ± 179 cells/mm(2) at 5 years. CCT decreased from 644 ± 67 μm before DMEK to 557 ± 49 μm at 5 years, with a minimum (530 ± 54 μm) at 3 months. Cumulative probability of 5-year graft survival was 95%.

CONCLUSIONS

The long-term sustainability of DMEK was confirmed. DMEK not only provides fast visual rehabilitation but maintains its clinical outcome within a follow-up of 5 years. Visual acuity and endothelial cell loss remain stable between 3 months and 5 years after DMEK.