"OSMO-UT-DSAEK" using THIN-C medium

Efficacy of Thin and Ultrathin Descemet Stripping Automated Endothelial Keratoplasty and Influence of Graft Thickness on Postoperative Outcomes: Systematic Review and Meta-analysis

PURPOSE

To conduct a systematic review and meta-analysis on the efficacy of thin and ultrathin Descemet stripping automated endothelial keratoplasty (T-DSAEK and UT-DSAEK, with graft thickness <130 and <100 µm, respectively), depending on graft thickness.

DESIGN

Systematic review and meta-analysis.

METHOD

PubMed, Cochrane Library, Embase, ClinicalTrials.gov, and ScienceDirect databases were searched until October 1, 2021. We computed random-effect meta-analysis on postoperative outcomes of T/UT-DSAEK, stratified by graft thickness (<80 μm, 80-100 μm, and 100-130 μm). The main postoperative outcome was visual acuity (logarithm of the minimum angle of resolution [logMAR]). Secondary outcomes were pachymetry (μm), endothelial cell count (cell/mm²), spherical equivalent (diopter [D]), rebubbling rate (%), and rejection rate (%). Meta-regressions compared postoperative outcomes depending on graft thickness and search for putative confusion factors.

RESULTS

We included 47 articles for a total of 2141 eyes of 2040 patients. T/UT-DSAEK globally improved visual acuity (effect size = -0.38 logMAR [95% confidence interval {CI} -0.46 to -0.30 logMAR]), without difference depending on graft thickness. Overall, pachymetry improved (-60.6 µm [95% CI -101 to -19.7 µm]), endothelial cell count decreased (-1039 cells/mm² [95% CI -1209 to -868 cells/mm²), spherical equivalent resulted in a hyperopic shift (0.74 D [95% CI -0.50 to 1.97 D), the graft rejection rate was 0.2% (95% CI -0.1% to 0.4%), and the rebubbling rate was 8.7% (95% CI 6.8%-10.5%). Grafts >100 μm induced a hyperopic shift. Metaregressions did not demonstrate differences between the 3 groups (<80 μm, 80-100 μm, or 100-130 μm) in any outcomes.

CONCLUSION

All T/UT-DSAEK thickness groups provided similar visual acuity, pachymetry, endothelial cell count, rejection rate, and rebubbling rate regardless of graft thickness. A hyperopic shift was induced by grafts >100 μm.

Nomogram for single-pass automated microkeratome graft preparation for ultrathin Descemet stripping automated endothelial keratoplasty

PURPOSE

To create a nomogram including the translational speed of the microkeratome blade, microkeratome head size and precut tissue thickness to predict the postcut thickness for Descemet stripping automated endothelial keratoplasty to obtain the thinnest possible graft.

METHODS

This prospective study incorporated 48 grafts for DSAEK from March 2017 to June 2020. Corneal tissue for DSAEK was prepared by 3 experienced physicians using the Moria Evolution 3E (Moria Inc, Antony, France) microkeratome with 400, 450 and 500 μm head sizes. Precut central corneal thickness was measured with a DGH 550 handheld pachymeter (Pachette 2), taking an average of 3 readings. The microkeratome head was selected according to precut tissue thickness. The selected microkeratome head size was 150 μm less than the donor cornea thickness. Two translational speeds were used for the microkeratome cuts. One month after surgery, the central lenticular thickness was measured with a Visante® Optical Coherence Tomography caliper (Carl Zeiss Meditec Inc, Germany). A descriptive analysis was performed.

RESULTS

Forty-eight donor grafts were prepared. Mean graft thickness was 97.58 ± 29.84 μm (range 39-176 μm). Of the 48 samples, central graft thickness was < 120 µm (81.3%) in 39, < 100 µm (58.3%) in 28 and < 80 µm (37.5%) in 18 at 1-month follow-up. There were no statically significant differences between translational speeds.

CONCLUSIONS

A nomogram with an automated microkeratome to obtain thin grafts for DSAEK provided good graft thickness results without donor waste.

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.

Preparation of ultrathin grafts for Descemet-stripping endothelial keratoplasty with a single microkeratome pass

We present a technique to achieve ultrathin Descemet-stripping automated endothelial keratoplasty (DSAEK). Using a simple method of controlling artificial anterior chamber pressure and drying the corneal surface, it was possible to thin the donor cornea at a rate of 11 μm a minute. When the donor cornea was between 500 μm and 510 μm, a single pass was made using a 350 μm microkeratome head followed by a peripheral dissection. The resulting mean graft thickness was 83.2 μm ± 14.9 (SD) (range 50 to 98 μm) with a mean peripheral graft edge thickness of 106.8 ± 10.9 μm (range 90 to 120 μm). There were no surgical complications, and all grafts remained attached. This is a reliable method for preparing ultrathin donor corneal lenticules for DSAEK in the operating room or eye bank without using multiple microkeratome heads or risking double passes.

Immune reactions after modern lamellar (DALK, DSAEK, DMEK) versus conventional penetrating corneal transplantation

In the past decade, novel lamellar keratoplasty techniques such as Deep Anterior Lamellar Keratoplasty (DALK) for anterior keratoplasty and Descemet stripping automated endothelial keratoplasty (DSAEK)/Descemet membrane endothelial keratoplasty (DMEK) for posterior keratoplasty have been developed. DALK eliminates the possibility of endothelial allograft rejection, which is the main reason for graft failure after penetrating keratoplasty (PK). Compared to PK, the risk of endothelial graft rejection is significantly reduced after DSAEK/DMEK. Thus, with modern lamellar techniques, the clinical problem of endothelial graft rejection seems to be nearly solved in the low-risk situation. However, even with lamellar grafts there are epithelial, subepithelial and stromal immune reactions in DALK and endothelial immune reactions in DSAEK/DMEK, and not all keratoplasties can be performed in a lamellar fashion. Therefore, endothelial graft rejection in PK is still highly relevant, especially in the "high-risk" setting, where the cornea's (lymph)angiogenic and immune privilege is lost due to severe inflammation and pathological neovascularization. For these eyes, currently available treatment options are still unsatisfactory. In this review, we will describe currently used keratoplasty techniques, namely PK, DALK, DSAEK, and DMEK. We will summarize their indications, provide surgical descriptions, and comment on their complications and outcomes. Furthermore, we will give an overview on corneal transplant immunology. A specific focus will be placed on endothelial graft rejection and we will report on its incidence, clinical presentation, and current/future treatment and prevention options. Finally, we will speculate how the field of keratoplasty and prevention of corneal allograft rejection will develop in the future.

Cross-Country Transportation Efficacy and Clinical Outcomes of Preloaded Large-Diameter Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty Grafts

PURPOSE

To evaluate the clinical outcomes of preloaded large-diameter ultra-thin grafts for Descemet stripping automated endothelial keratoplasty (UT-DSAEK) after cross-country shipment.

METHODS

A laboratory study in an eye bank and a clinical cohort study in an academic tertiary care center were performed. UT-DSAEK (9.5 mm diameter) grafts (n = 7) were prepared, loaded into a commercial device (iGlide; Eurobio, Les Ulis, France), preserved for 4 days at room temperature in transport medium, and analyzed. In a retrospective study, preloaded tissues (n = 39) for clinical use were prepared, transported from Italy to the United Kingdom, and surgically delivered into the eyes of patients undergoing UT-DSAEK. Central and peripheral endothelial cell density (ECD) and viability were measured before and after loading and storage of the grafts in the laboratory study. Clinically, best-corrected visual acuity, ECD before and at final follow-up, dislocation rate, primary graft failure, and surgical time were recorded.

RESULTS

In the laboratory study, postcut central graft thickness was 93.3 ± 17.2 μm. ECD and cell mortality did not change significantly before and after preservation (P = 0.8). Cell loss after 4 days of preservation was 1.7% ± 1.6%. Clinically, 39 eyes of 39 patients at final follow-up showed a mean central graft thickness of 88 ± 22 μm and a best-corrected visual acuity of 0.34 ± 0.24 logMAR. Nine of 39 cases (23%) needed rebubbling, and 28% cell loss was observed at final follow-up.

CONCLUSIONS

Large-diameter UT-DSAEK grafts can be prepared and preloaded in the eye bank using the iGlide and transported to the surgical center facilitating surgery for patients undergoing UT-DSAEK, potentially reducing tissue wastage, surgical time, and costs related to surgery.

Deformation velocity imaging using optical coherence tomography and its applications to the cornea

Optical coherence tomography (OCT) can monitor human donor corneas non-invasively during the de-swelling process following storage for corneal transplantation, but currently only resultant thickness as a function of time is extracted. To visualize and quantify the mechanism of de-swelling, we present a method exploiting the nanometer sensitivity of the Fourier phase in OCT data to image deformation velocities. The technique was demonstrated by non-invasively showing during de-swelling that osmotic flow through an intact epithelium is negligible and removing the endothelium approximately doubled the initial flow at that interface. The increased functional data further enabled the validation of a mathematical model of the cornea. Included is an efficient method of measuring high temporal resolution (1 minute demonstrated) corneal thickness, using automated collection and semi-automated graph search segmentation. These methods expand OCT capabilities to measure volume change processes for tissues and materials.

Effect of Graft Thickness on Visual Acuity After Descemet Stripping Endothelial Keratoplasty: A Systematic Review and Meta-Analysis

PURPOSE

To assess the relationship between graft thickness and best-corrected visual acuity (BCVA) after Descemet stripping endothelial keratoplasty (DSEK).

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, EMBASE, Web of Science, and conference abstracts were searched for studies published up to October 2015 with standard systematic review methodology. Eligibility criteria included studies evaluating graft thickness in primary DSEK and visual outcomes. There were no restrictions to study design, study population, or language. Correlation coefficients were pooled using random-effects models.

RESULTS

Of 480 articles and conference abstracts, 31 met inclusion criteria (2214 eyes) after full-text review. Twenty-three studies assessed correlations between BCVA and graft thickness, and 8 studies used different statistical methods. All associations were reported dimensionless. Studies generally had small sample sizes and were heterogeneous, especially with respect to data and analysis quality (P = .02). Most studies did not measure BCVA in a standardized manner. The pooled correlation coefficient for graft thickness vs BCVA was 0.20 (95% CI, 0.14-0.26) for 17 studies without data concerns; this did not include 7 studies (815 eyes) that used different statistical methods and did not find significant associations.

CONCLUSIONS

There is insufficient evidence that graft thickness is clinically important with respect to BCVA after DSEK, with meta-analysis suggesting a weak relationship. Although well-designed longitudinal studies with standardized measurements of visual acuity and graft thickness are necessary to better characterize this relationship, current evidence suggests that graft thickness is not important for surgical planning.

A year of cornea in review: 2013

PURPOSE

The goal of this study was to provide an update of significant corneal literature published in 2013.

DESIGN

This study is a systematic literature review.

METHODS

We conducted a systematic review of the English-language literature published from January 1, 2013, to December 31, 2013, using the following PubMed search and Medical Subject Headings terms: cornea transplantation, keratoplasty, Descemet membrane endothelial keratoplasty, Descemet stripping endothelial keratoplasty, cross linking, pre-Descemet's layer, Rho-associated kinase, keratoprosthesis, infectious keratitis, corneal dystrophy, corneal astigmatism, and keratoconus.

RESULTS

This review summarizes relevant and innovative original articles, review articles, and novel techniques from the following journals: American Journal of Ophthalmology, British Journal of Ophthalmology, Cornea, Graefe's Archive for Clinical and Experimental Ophthalmology, Investigative Ophthalmology & Visual Science, JAMA Ophthalmology, Journal of Cataract and Refractive Surgery, Journal of Refractive Surgery, and Ophthalmology. Case reports, abstracts, letters to the Editor, and unpublished work were excluded, as well as articles e-published ahead of print in 2012 that were discussed in the previous review. One hundred twenty-seven articles met the criteria for this review.

CONCLUSIONS

This review summarizes significant cornea-related literature from 2013.

Does thickness matter: ultrathin Descemet stripping automated endothelial keratoplasty

PURPOSE OF REVIEW

Descemet stripping automated endothelial keratoplasty (DSAEK) has become worldwide the procedure of choice for the replacement of diseased corneal endothelium. More recently, ultrathin DSAEK (UT-DSAEK) has been introduced to guarantee better visual outcomes preserving good donor graft manipulation.

RECENT FINDINGS

As DSAEK may still have major challenges such as suboptimal visual acuity and relatively slow visual rehabilitation, fairly new techniques such as UT-DSAEK and Descemet membrane endothelial keratoplasty (DMEK) have been introduced to allow much quicker and optimal visual rehabilitation. This article goes through the most recent findings and results of these techniques.

SUMMARY

UT-DSAEK is a procedure that shares the improved visual outcome and lower immunologic rejection rate of DMEK over DSAEK, while minimizing all types of postoperative complications. In addition, similar to DSAEK and unlike DMEK, UT-DSAEK can be performed in all types of eyes, even in those with complicated anatomy or poor anterior chamber visualization.