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

Ten-Year Changes in Vision, Refractive Error, and Corneal Thickness After Descemet Stripping Automated Endothelial Keratoplasty for Fuchs Endothelial Corneal Dystrophy

PURPOSE

The goal of this study was to determine changes in best-corrected visual acuity (BCVA), refractive error, and central corneal thickness (CCT) during the first decade after Descemet stripping automated endothelial keratoplasty (DSAEK).

METHODS

Outcomes of all consecutive eyes undergoing DSAEK for Fuchs endothelial corneal dystrophy (FECD) were reviewed; eyes with untreatable comorbidities before DSAEK were excluded. DSAEK was performed through a temporal incision and all eyes were pseudophakic postoperatively. Changes in BCVA, manifest spherical equivalent, manifest cylinder (vector analysis), and CCT were assessed by using generalized estimating equation models.

RESULTS

BCVA improved between 6 months (0.18 ± 0.12 logarithm of the minimum angle of resolution (logMAR); Snellen equivalent, 20/30) and 5 years (0.10 ± 0.10 logMAR; 20/25; n = 74, P < 0.001) and then remained stable at 10 years (0.09 ± 0.10 logMAR, n = 48, P = 0.22). There was a myopic shift of -0.20 ± 0.51 D between 6 months and 5 years (n = 65, P = 0.002) that remained stable at 10 years (-0.09 ± 0.44 D; 20/25; n = 34, P = 0.33). Manifest cylinder drifted with-the-rule between 6 months and 5 years (n = 65, P < 0.001) and between 5 and 10 years (n = 34, P < 0.001). CCT was stable between 6 months (672 ± 57 μm) and 5 years (677 ± 55 μm, n = 67, P = 0.47), but increased at 10 years (702 ± 60 μm, n = 39, P = 0.001).

CONCLUSIONS

Excellent BCVA can be achieved during the first decade after DSAEK for FECD, although improvement seems to plateau after 5 years. Changes in manifest refractive error were not clinically significant. The gradual increase in CCT was consistent with longer-term changes found after other types of keratoplasty.

Donor lamella thickness after ultrathin Descemet stripping automated endothelial keratoplasty and its relation to postoperative visual acuity and pre-operative lamella measures

BACKGROUND

To accurately measure ultrathin Descemet stripping automated endothelial keratoplasty (DSAEK) donor lamella thickness during the first postoperative year and to correlate this with pre-operative and other postoperative measurements.

METHODS

Donor lamella thickness in 41 eyes undergoing DSAEK for Fuchs endothelial dystrophy (FED) was measured using the Tomey Casia OCT directly after graft preparation and at 1 week and 1, 3, 6 and 12 months postoperatively. Visual acuity and endothelial cell density were measured as the secondary parameters.

RESULTS

Individual graft thickness profiles were shown to be fairly regular within the optically relevant area. There was a strong and highly significant correlation between the pre- and postoperative lamellar thicknesses at all time points (p < 0.0001). Compared with the measurements directly after preparation at the cornea bank, the lamella thickness decreased by 12% after 12 months. Between 1 and 12 months postoperatively, the lamella thickness (mean ± SD) changed from 112 ± 27 μm to 101 ± 21 μm. Best spectacle-corrected visual acuity (BSCVA) changed from 0.46 ± 0.30 logMAR pre-operatively through 0.36 ± 0.33 at 1 month to 0.13 ± 0.16 at 1 year postoperatively. The endothelial cell counts were comparable to those reported in previous studies.

CONCLUSIONS

Thickness profiles of individual grafts were fairly regular within the optically relevant area. A strong relationship between pre- and postoperative graft thicknesses was detected, and ultrathin DSAEK grafts prepared using methods similar to that applied in this study are expected to show a deswelling of around 12% during the first postoperative year. No correlation was detected between graft thickness and BSCVA.

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.

[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.

Standardized pachymetry-assisted manual lamellar dissection for Descemet stripping endothelial keratoplasty

PURPOSE

To present an alternative technique (Pachy-DSEK) for the manual preparation of thin endothelial lamellae in Descemet stripping endothelial keratoplasty (DSEK), as well as to evaluate its visual and anatomic outcomes.

METHODS

A retrospective chart review was conducted in 15 cases who underwent DSEK at a private eye clinic in Brazil (INOB, Brasília) from June 2017 to December 2019. All patients had ocular comorbidities and relative contraindications to Descemet membrane endothelial keratoplasty (DMEK). All endothelial lamellae were manually prepared by using a standardized technique. Best corrected visual acuity (BCVA), tomographic parameters and graft's thickness were evaluated preoperatively and at 6 months. Endothelial cell counts were evaluated preoperatively and at 12 to 24 months.

RESULTS

During preparation there was one case (6%) of peripheral tear and no tissue was lost. At 6 months, the median BCVA improved from 1.60 to 0.40 logMAR (p = 0.0009). There was no significant change in anterior (p = 0.507) and posterior astigmatism (p = 0.483), anterior (p = 0.683) and posterior mean keratometry (p = 0.767), and total corneal power (p = 0.952). The median central graft thickness at 6 months was 80 µm. Ultrathin grafts (<130 µm) were achieved in 80% of cases. At 12 to 24 months endothelial cell count decreased significantly. Graft's detachment occurred in two cases (13%) and endothelial rejection in one case (6%).

CONCLUSION

By using ultrasonic pachymetry intra-operatively and standardizing graft preparation, most manually dissected endothelial lamellae were ultrathin. Pachy-DSEK was safe and effective for treating endothelial disfunction in eyes with ocular comorbidities. It may be a cost-effective alternative to automated dissection methods.

New Technologies in Clinical Trials in Corneal Diseases and Limbal Stem Cell Deficiency: Review from the European Vision Institute Special Interest Focus Group Meeting

To discuss and evaluate new technologies for a better diagnosis of corneal diseases and limbal stem cell deficiency, the outcomes of a consensus process within the European Vision Institute (and of a workshop at the University of Cologne) are outlined. Various technologies are presented and analyzed for their potential clinical use also in defining new end points in clinical trials. The disease areas which are discussed comprise dry eye and ocular surface inflammation, imaging, and corneal neovascularization and corneal grafting/stem cell and cell transplantation. The unmet needs in the abovementioned disease areas are discussed, and realistically achievable new technologies for better diagnosis and use in clinical trials are outlined. To sum up, it can be said that there are several new technologies that can improve current diagnostics in the field of ophthalmology in the near future and will have impact on clinical trial end point design.

Towards Clinical Trials in Fuchs Endothelial Corneal Dystrophy: Classification and Outcome Measures-The Bowman Club Lecture 2019

The surgical treatment of Fuchs endothelial corneal dystrophy (FECD) has advanced dramatically over the last two decades. Penetrating keratoplasty has been superseded by various iterations of endothelial keratoplasty, and currently, surgical removal of host Descemet membrane without keratoplasty is being investigated. These surgical advances have been accompanied by significant improvement of our understanding of the underlying disease mechanisms, not least the discovery that FECD in western populations is predominantly an intronic trinucleotide repeat expansion disorder in the transcription factor 4 gene that results in RNA toxicity and mis-splicing. Understanding the disease mechanisms augurs well for developing targeted molecular medical therapies, which will require careful clinical investigation through trials to prove their efficacy and safety. As the field advances towards clinical trials, investigators should carefully define the disease state being treated and consider the options for outcome measures relevant to the type of intervention. FECD, and the outcomes of interventions to treat the disease, can be measured in terms of corneal morphology, corneal function and clinical impact. Standardising the approach for defining FECD and careful thought about the outcomes of intervention that are reported will help make the results of future trials for FECD applicable in clinical practice.

Different graft thicknesses after Descemet stripping endothelial keratoplasty for bullous keratopathy in the two eyes of the same patient

Objective

To describe a very unique case of two Descemet stripping automated endothelial keratoplasty (DSAEK) surgeries performed in both eyes of the same patient with an extremely different graft thickness and overall corneal thickness but with the same corrected distance visual acuity (CDVA) 2 years after surgery.

Case presentation

A 75-year-old woman with bilateral bullous keratopathy (BK) was submitted to DSAEK surgeries in both eyes, first in right and after 6 months in left eye. CDVA was 20/160 in the right eye and 20/63 in the left eye. Corneal thickness evaluated by anterior segment optical coherence tomography was 569 µm in the right eye and 560 µm in the left eye. The root mean square (RMS) was 2.1 in the right and left eyes. Endothelial cell densities were not detectable in both eyes. The estimated precut donor graft thickness from eye bank was 250 and 40 µm in the right and in the left graft, respectively. Two years after surgery CDVA was 20/25 in both eyes. Corneal thickness was 633 µm with a lenticule thickness of 206 µm in the right eye and 439 µm with a lenticule thickness of 48 µm in the left eye. The RMS was 1.7 in the right eye and 1.4 in the left eye. Endothelial cell density was 2.272 cells/mm² in the right and 2.154 cells/mm² in the left eye.

Conclusion

DSAEK was safe and effective in the treatment of BK. In our report, the visual outcome resulted to be poorly related either to donor graft thickness or to postoperative corneal thickness.

Visual Outcomes of Ultrathin-Descemet Stripping Endothelial Keratoplasty versus Descemet Stripping Endothelial Keratoplasty

Purpose

To examine the impact of graft thickness (GT) on postoperative visual acuity and endothelial cell density after ultrathin-Descemet stripping automated endothelial keratoplasty (UT-DSAEK) versus conventional DSAEK.

Methods

The medical records of all patients who underwent DSAEK at our institute during a 2-year period were reviewed. After excluding subjects with low visual potential, 34 eyes were divided into two groups based on the postoperative GT as measured with anterior segment optical coherence tomography (AS-OCT): an UT-DSAEK group (GT ≤ 100 μm, n=13 eyes) and a DSAEK group (GT > 100 μm, n=21 eyes). The groups were compared with regard to best-corrected visual acuity (BCVA), subjective refraction, central corneal thickness (CCT), GT, and endothelial cell density (ECD).

Results

Preoperative BCVA (logMAR) was 1.035 ± 0.514 and 0.772 ± 0.428 for UT-DSAEK and DSAEK, respectively (P=0.072). At 6 months postoperatively, BCVA was 0.088 ± 0.150 following UT-DSAEK and 0.285 ± 0.158 following DSAEK (P=0.001).

Conclusion

DSAEK grafts with a thickness under 100 μm offered better visual outcomes during the early postoperative period.

Corneal Optical Changes Associated with Induced Edema in Fuchs Endothelial Corneal Dystrophy

PURPOSE

Patients with Fuchs endothelial corneal dystrophy (FECD) often notice poor vision in the morning that improves as the day progresses. In this study, we determined changes in corneal optical properties associated with induced corneal edema.

METHODS

Twenty-three phakic eyes (23 participants) with FECD (grades 1-6, modified Krachmer scale) and 8 normal eyes (8 participants) were examined by Scheimpflug photography. Central corneal thickness, high-order aberrations from anterior and posterior corneal surfaces, and backscatter from the anterior, mid-, and posterior cornea were determined from the Scheimpflug images. A low-oxygen permeable contact lens was placed on the eye, and eyes were closed for 2 hours, after which the lens was removed and Scheimpflug photography was repeated for up to 5 hours to determine changes in backscatter and high-order aberrations.

RESULTS

Corneas swelled by 10% [95% confidence interval (CI), 9-10]. Backscatter from the anterior cornea increased by 416 scatter units (SU, 95% CI, 344-488; P < 0.001), independent of the presence and severity of FECD. Recovery of anterior backscatter was slower in advanced FECD (81 SU/h, 95% CI, 60-120) compared with normal (123 SU/h, 95% CI, 95-150; P = 0.019). Anterior and posterior corneal high-order aberrations, and mid and posterior backscatter, did not increase with induced swelling.

CONCLUSIONS

Inducing corneal edema increases anterior corneal backscatter but not high-order aberrations. Subjective poor vision in the morning in FECD is probably caused by scattered light rather than by high-order aberrations, suggesting that these patients experience more disability glare than decreased visual acuity.

Long-Term Functional and Anatomical Outcome after Descemet Stripping Automated Endothelial Keratoplasty: A Prospective Single-Center Study

Purpose

To investigate the long-term anatomical and functional outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods

Prospective follow-up of 114 eyes (95 subjects) after DSAEK for endothelial dysfunction. Measurements included best spectacle-corrected visual acuity (BSCVA), straylight, endothelial cell density (ECD), and graft thickness.

Results

The mean follow-up time was 5.1 ± 1.5 years. Four grafts ultimately failed (after 5 to 7 years). From baseline up to 1 year after DSAEK, mean BSCVA improved by 0.30 logMAR. This beneficial effect remained until the last follow-up (LFU). After DSAEK, straylight was reduced. ECD sharply dropped by 900 cells/mm² (33%) immediately after surgery and, thereafter, steadily decreased at a rate of 11 cells/mm² per month. No significant correlation was observed between graft thickness at 3 years and BSCVA.

Conclusions

We observed a low graft failure rate and a normalization of graft thickness. Postoperative straylight remained elevated relative to the normal population. The sharp initial and the subsequent more gradual ECD decline are consistent with other studies. A significant and prolonged functional gain can be achieved by posterior lamellar grafting for endothelial dysfunction.

Fuchs' endothelial corneal dystrophy: a controlled prospective study on visual recovery after endothelial keratoplasty

PURPOSE

To investigate the determining factors of vision and subjective outcome after Descemet's stripping automated endothelial keratoplasty (DSAEK) for Fuchs' endothelial dystrophy (FECD).

METHODS

In a prospective study, 41 FECD patients who received DSAEK were compared to 40 cataract patients with normal corneas who received cataract surgery (control group). Subjects were recruited between March 2013 and July 2014. Observational procedures included the following: best-corrected visual acuity (BCVA), contrast sensitivity (CS), Catquest-9SF questionnaire, Scheimpflug tomography and anterior OCT. Examinations were carried out before surgery and at 3-, 6- and 12-month follow-up. Main outcome measures were associations between corneal optics and visual parameters, as well as subjective improvement (Catquest-9SF effect size) RESULTS: Best-corrected visual acuity (BCVA) negatively correlated with anterior higher-order aberrations (HOA's) (p < 0.001) and central corneal thickness (p = 0.001). Contrast sensitivity (CS) was negatively correlated with anterior HOA's (p = 0.002) and positively correlated with posterior densitometry (p = 0.008). Catquest-9SF effect size was 1.32 (CI: 1.0-1.6) in the control group, 1.84 (CI: 1.4-2.3) in FECD patients who received phacoemulsification and intra-ocular lens implantation in combination with DSAEK (n = 26) and 1.37 (CI: 0.6-2.1) in pseudophakic FECD patients who received DSAEK (n = 15).

CONCLUSIONS

DSAEK surgery leads to considerable improvement in patient-reported outcome in FECD patients. There was a strong correlation between anterior HOA's and vision after DSAEK, suggesting that anterior corneal pathology constitutes the major limitation for visual recovery after DSAEK.