Ultrathin Descemet stripping automated endothelial keratoplasty

Modified Method for Nanothin Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

The purpose of this study was to describe a method to achieve a high success rate for nanothin (NT, ≤50 μm) Descemet stripping automated endothelial keratoplasty (DSAEK) graft preparation using anterior chamber pressurizer (ACP) with a modified setting and evaluate its postoperative efficacy.

METHODS

A prospective cohort (study group) of 24 patients with corneal endothelial dysfunction was consecutively enrolled and received DSAEK grafts using the modified ACP method from December 2021 to May 2022. The control group included 24 historical patients who received DSAEK grafts using conventional ACP procedure. Central graft thickness (CGT), graft regularity (3-mm and 5-mm diameter zones), best spectacle-corrected visual acuity, and endothelial cell density (ECD) were compared between 2 groups.

RESULTS

A 100% ultrathin (UT, ≤100 μm) DSAEK rate and 62.5% NT-DSAEK rate was achieved at 3 months postsurgery in the study group, with a 51.3 ± 14.8 μm CGT, while a 70.8% UT-DSAEK rate and 4.2% NT-DSAEK rate was achieved in the control group, with an 89.0 ± 15.4 μm CGT (P <0.001). At 3-month postoperative follow-up, the regularity of graft thickness was significantly better in the study group (central-to-peripheral thickness difference: P = 0.044 and 0.014 for 3-mm and 5-mm diameter zones, respectively, graft thickness uniformity: P <0.001 and 0.012, respectively). There was no statistical difference in the best spectacle-corrected visual acuity (P = 0.170) or ECD (P = 0.833) between 2 groups at 3-month postoperative follow-up.

CONCLUSIONS

DSAEK grafts harvested using modified ACP method were thinner and more regular compared with the conventional ACP method.

[Modern techniques and features of selective keratoplasty]

Selective keratoplasty involves replacing the affected layers of the cornea with similar donor tissue. In case of pathological changes in the middle and posterior stroma, deep anterior lamellar keratoplasty (DALK) is performed. Chronic corneal edema caused by endothelial dysfunction is an indication for endothelial keratoplasty - Descemet membrane endothelial keratoplasty (DMEK) or Descemet Stripping Endothelial Keratoplasty (DSAEK). Compared to penetrating keratoplasty (PK), these operations are characterized by a low risk of damage to intraocular structures and a relatively short rehabilitation period. Complications of selective keratoplasty include the formation of a false chamber between the lamellar graft and the recipient's cornea, ocular hypertension during anterior chamber air tamponade. Persistent epithelial defect can be a sign of primary graft failure in DALK, DSAEK and DMEK. Selective keratoplasty is characterized by a lower incidence of immune rejection than PK. In some cases, DALK can be complicated by corneal changes related to suture fixation of the graft. Long-term postoperative use of topical glucocorticoids can cause ocular hypertension and cataracts.

Descemet membrane endothelial keratoplasty compared with ultrathin Descemet stripping automated endothelial keratoplasty: a meta-analysis

AIMS

This study aims to compare the clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) in patients with corneal endothelial dysfunction due to Fuchs' endothelial dystrophy or pseudophakic bullous keratopathy.

METHODS

We conducted a meta-analysis using a literature search of Embase, PubMed, Cochrane CENTRAL, ClinicalTrials.gov and WHO ICTRP databases. We included randomised controlled trials (RCTs) and cohort studies that compared DMEK and UT-DSAEK (graft<130 µm), with a follow-up of ≥12 months, published until 20 February 2022. We used the Revised Cochrane risk-of-bias tool for RCTs and the Risk of Bias in Non-Randomised Studies-of Interventions system for cohort studies.

RESULTS

Out of 144 records, 8 studies (3 RCTs, 2 fellow-eye studies and 3 cohort studies) were included, encompassing 376 eyes, (N=187 DMEK vs N=189 UT-DSAEK). The 12-month logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) was better post-DMEK (mean difference -0.06 (95% CI -0.10 to -0.02)), but with higher rebubbling risk: OR 2.76 (95% CI 1.46 to 5.22). Heterogeneity was significant I2=57%. Findings were consistent when excluding retrospective studies, including only studies with low risk of bias or RCTs only. An analysis of studies with mean DSAEK grafts <70 µm showed no significant difference in BCVA between the procedures. Publication bias was found in the BCVA analysis (Egger's test p=0.023).

CONCLUSIONS

Post-DMEK BCVA is superior to post-UT-DSAEK when using <130 µm grafts. DSAEK grafts <70 µm may not significantly differ from DMEK. The higher risk of rebubbling with DMEK necessitates an appropriate selection of patients.

PROSPERO REGISTRATION NUMBER

CRD42022340805.

[Risk factors for failure of pre-cut eye bank UT-DSAEK grafts]

INTRODUCTION

The main risk factors for graft failure in penetrating keratoplasty are well known. However, few studies have examined donor characteristics or more precise data on endothelial keratoplasty.

MATERIALS AND METHODS

This was a retrospective, single-center study at the Nantes University Hospital, aiming to identify factors predictive of one-year success or failure of eye bank UT-DSAEK endothelial keratoplasty grafts prepared between May 2016 and October 2018. The outcome measure was success or failure at 12months post keratoplasty.

RESULTS

One hundred and five grafts were included: 93 successes and 12 failures at 12months. The failure rate was higher in 2016 compared to 2017 and 2018. The characteristics associated with higher failure rate were elderly donor, shorter time between harvesting and grafting, lower endothelial cell density, significant pre-graft endothelial cell loss, re-graft for Fuchs dystrophy, history of corneal transplant.

DISCUSSION

Our results are consistent with those in the literature. However, some factors, such as the type of corneal harvesting or pre-graft endothelial cell loss, were not found. UT-DSAEK has demonstrated better results than DSAEK, but still appears to be somewhat inferior to DMEK.

CONCLUSION

The main factor for graft failure in our study was an early re-graft within 12months. However, the low incidence of graft failure limits interpretation of these results.

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.

Clinical Outcomes of Nanothin Descemet Stripping Automated Endothelial Keratoplasty in Korean patients with Corneal Endothelial Dysfunction

Purpose

To evaluate the clinical outcomes of nanothin Descemet stripping automated endothelial keratoplasty (DSAEK) in Korean patients with corneal endothelial dysfunction.

Methods

We retrospectively reviewed medical records of the patients who underwent nanothin DSAEK (graft thickness ≤50 μm) due to corneal endothelial dysfunction and followed up more than 1 year. We evaluated best-corrected visual acuity (BCVA), central corneal thickness, and corneal endothelial cell density at preoperative and 1, 3, 6, and 12 months postoperatively.

Results

Sixteen eyes of 16 patients with the mean follow-up period of 13.00 ± 0.96 months were included. The mean graft thickness after deswelling was 45.25 ± 4.59 μm (range, 38.0–50.0 μm). The mean logarithm of the minimum angle of resolution BCVA improved from 1.37 ± 0.53 preoperatively to 0.68 ± 0.46, 0.55 ± 0.35, 0.40 ± 0.25, and 0.39 ± 0.25 at 1, 3, 6, and 12 months postoperatively (p = 0.005, p < 0.001, p < 0.001, and p < 0.001), respectively. The mean central corneal thickness improved from 752.00 ± 129.11 to 555.75 ± 54.66 μm at 12 months postoperatively (p = 0.006). The mean graft endothelial cell density decreased from 2,859.62 ± 228.34 to 1,542.25 ± 627.34 cells/mm² at 12 months postoperatively (p = 0.012). The postoperative complications included increased intraocular pressure (n = 3, 18.75%) and graft dislocation (n = 1, 6.25%), all of which were successfully managed by anterior chamber paracentesis or rebubbling. No other serious complications were encountered.

Conclusions

Nanothin DSAEK produced significant and stable visual improvements without severe postoperative complications in Korean patients with corneal endothelial dysfunction.

Evaluation of Donor and Recipient Characteristics Involved in Descemet Stripping Automated Endothelial Keratoplasty Outcomes

Aims: To evaluate both donor and recipient features involved in visual acuity restoring and complication insurgence in eyes that have undergone Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods: In this retrospective study, charts of 111 eyes of 96 patients (mean age 70.25 ± 8.58 years) that underwent DSAEK were evaluated. Only Fuch's Distrophy (FD) or Bullous Keratopathy (BK) due to cataract surgery eyes were included. A complete ophthalmic check with endothelial cell density (ECD) and central corneal thickness (CCT) measurement was performed before surgery and at 1, 3, 6, and 12 months follow-up. Each DSAEK was performed by the same well-trained surgeon; only pre-cut lenticules, provided by same Eye Bank, were implanted.

Results: A total of 48 (43%) complications have been observed (most of them were 22 partial graft detachments and 17 IOP spikes). At the last follow-up (mean: 8.58 ± 4.09 months), a significant increase (p < 0.05) of best corrected visual acuity (BCVA) was detected. Overall mean BCVA of the eyes evaluated was 0.40 ± 0.43 LogMAR with BK eyes showing a significantly higher improvement (p < 0.05) compared to FD eyes. The only factor showing a significant correlation (p < 0.05) with visual acuity enhancement was the implant of a lenticule thinner than 100 μm. Recipient features significantly (p < 0.05) associated with complications observed after surgery were glaucoma and diabetes mellitus.

Conclusion: The use of a graft thinner than 100 μm can provide better visual acuity recovery while recipients affected by glaucoma or diabetes mellitus are more prone to develop complications after surgery.

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.

[UT-DSAEK using grafts provided by a tissue bank, a one-year follow-up study of 79 grafts]

INTRODUCTION

UT-DSAEK is a recent technique developed in order to obtain grafts thinner than a conventional DSAEK (less than 100 microns). The goal of this study was to evaluate the anatomic and clinical results over a period of one year for a retrospective series of UT-DSAEK procedures at the University Hospital of Nantes, using pre-cut grafts provided by a tissue bank, and to compare results with other existing techniques: DSAEK and DMEK.

METHODS

In this retrospective, single-center study, all patients requiring an endothelial graft over a one-year period were included. The criteria studied were visual acuity, graft thickness, pachymetry and specular microscopy, recorded on the preoperative visit, D7, M1, M3, M6 and M12.

RESULTS

Seventy-nine grafts were performed on 75 patients. The mean age was 72 years. Between the 7th day and the end of the first year, the graft thickness in the visual axis decreased from 75±29 to 60±21 microns rapidly over the first three months. The pachymetry decreased from 706±95 microns preoperatively to 561±54 microns with the same kinetics. The cell density of the graft decreased from 2604±13 cell/mm² prior to the procedure to 1551±124 cell/mm² (40% loss) at one year. The preoperative visual acuity was 1.16 logMAR, rapidly improving to 0.65 logMAR at the first month and 0.40 logMAR at one year.

CONCLUSION

This study provides a fair amount of data on the progression of UT-DSAEK grafts: a decrease in graft thickness over the first three months, corresponding to an increase in visual acuity over this same period, with a good endothelial survival rate. This technique opens new avenues for the treatment of endothelial diseases, being complementary to DMEK in terms of surgical indications.

Corneal transplantation after failed grafts: Options and outcomes

Corneal transplantation is the most commonly performed human tissue transplantation procedure worldwide. Because of the large number of transplants, corneal graft failure has become one of the most common indications for corneal transplantation. The relatively recently developed lamellar transplant techniques have brought about specific potential complications leading to graft failure that may require different approaches to repeat transplantation other than penetrating keratoplasty. On the other hand, these new lamellar techniques also provide novel ways of rescuing failed penetrating grafts, with potential advantages over successive penetrating keratoplasties, such as reduced intraoperative risks and faster visual rehabilitation. We summarize the incidence and risk factors of graft failure for penetrating and lamellar (stromal and endothelial) corneal transplants and discuss the various surgical alternatives currently available to rescue such failed grafts, with a focus on the reported outcomes and limitations.