Determinants of visual quality after endothelial keratoplasty

Corneal densitometry patterns in Descemet membrane endothelial keratoplasty and Descemet stripping automated keratoplasty

PURPOSE

To compare corneal densitometry in a consecutive series of 52 endothelial keratoplasties (DMEK/DSAEK) using a Scheimpflug-based device after six months of follow-up.

METHODS

Corneal densitometry (CD) values of 102 eyes were divided into three main groups: 33 DMEKs, 19 DSAEKs, and 50 healthy eyes without previous ocular surgery. The CD values were then analyzed and compared between the groups. We measured three main layers in depth and four different concentric zones at 1, 3, and 6 months postoperatively.

RESULTS

In the DMEK group, total CD significantly decreased from 38.02 ± 10.21 grayscale units (GSU) to 31.13 ± 9.25 GSU (P < 0.01) between the first and the sixth month postoperative. In the DSAEK group, we found significant changes only between the first and three months after surgery (from 42.62 ± 9.31 GSU to 38.71 ± 10.53 GSU (P < 0.01). Regarding the concentric zones, CD in the DMEK group significantly decreased in the central zone from 33.55 ± 12.07 GSU to 30.63 ± 10.15 GSU (P < 0.01) and significantly increased in the periphery from 30.63 ± 10.15 GSU to 36.72 ± 9.37 GSU, (P < 0.01). The DSAEK group showed no changes in the central zone (from 36.91 ± 13.80 GSU to 36.14 ± 11.47 GSU, P = 0.52) and CD significantly increased in the periphery (41.91 ± 9.28 GSU, P < 0.01).

CONCLUSION

When comparing CD values in DMEK versus DSAEK, we found no differences by layers or at central-paracentral concentric zones, although CD differences in the peripheral zones were statistically significant. This finding may be attributed to the thicker graft at periphery with a delayed clearance and less anatomical interphase in DSAEK.

Scheimpflug Corneal Densitometry Patterns at the Graft-Host Interface in DMEK and DSAEK: A 12-Month Longitudinal Comparative Study

BACKGROUND

To compare corneal densitometry (CD) patterns at the graft-host interface between Descemet Membrane Endothelial Keratoplasty (DMEK) and Descemet Stripping Automated Endothelial Keratoplasty (DSAEK). Corneal densitometry is a quantitative assessment that objectively evaluates corneal clarity and optical quality by measuring the light backscatter from the cornea.

METHODS

Fifty-one eyes that received DMEK or DSAEK surgery for corneal endothelium dysfunction were evaluated. The primary endpoint included CD patterns at the graft-host interface, which were assessed by the Pentacam HR device at the center point of the corneal horizontal meridian (CDcentral), and at six points on the central circumference of the cornea (with a total diameter of 4 mm) (CDI,II,III,IV,V,VI). Secondary endpoints included the best-corrected distance visual acuity (BCDVA), central corneal thickness (CCT), and graft thickness (GT). All of the evaluations were performed at follow-up appointments one, three, six and twelve months after the procedure.

RESULTS

DMEK showed a significant overall CD reduction of -7.9 ± 8.5 grayscale unit (GSU) compared to DSAEK (p < 0.001). In addition, the DMEK group showed significantly lower CDCentral,I,II,III,IV,V,VI values at follow-up appointments one, three, six and twelve months after the procedure compared to the DSAEK group (p < 0.001). BCDVA, CCT and GT were in favor of the DMEK group with a mean value of 0.39 ± 0.35 LogMar, 552.2 ± 71.1 µm and 11.03 ± 1.4 µm, respectively (p < 0.001).

CONCLUSIONS

CD patterns at the graft-host interface seem to be different depending on the endothelial keratoplasty procedure. This provides specific insight into CD changes in this critical region of surgery, which may provide a better understanding of the postoperative evolution of these patients.

Optical quality of the cornea after Descemet membrane endothelial keratoplasty surgery: early results from Türkiye

Background

Descemet membrane endothelial keratoplasty (DMEK) is increasingly favored in the treatment of endothelial dysfunction due to its benefits, which include swift visual rehabilitation and recovery, a relatively low rejection rate, and superior refractive stability. In this study, we examined alterations in corneal clarity among patients who underwent DMEK and correlated these densitometry findings with other optical parameters of corneal topography.

Methods

The study incorporated 35 eyes from 35 patients who had previously undergone DMEK surgery for pseudophakic bullous keratopathy at Ankara Bilkent City Hospital. The results from these patients were compared with those from a healthy control group. The preoperative and postoperative optical parameters of the patients were assessed using Pentacam Scheimpflug topography (Oculus).

Results

We observed significant decreases in corneal densitometry in the 0-2 mm and 2-6 mm zones of the anterior, posterior, central, and total layers at the sixth month postoperatively compared to the preoperative period (P<0.05). The corneal densitometry values at postoperative month 6 were elevated in all layers and zones relative to the healthy group (P<0.05). The root mean square of higher-order aberrations in postoperative period was elevated significantly (P<0.001).

Conclusions

Six months after operation, the optical quality of the cornea following DMEK surgery did not achieve the level of a healthy cornea.

Biomaterials used for tissue engineering of barrier-forming cell monolayers in the eye

Cell monolayers that form a barrier between two structures play an important role for the maintenance of tissue functionality. In the anterior portion of the eye, the corneal endothelium forms a barrier that controls fluid exchange between the aqueous humor of the anterior chamber and the corneal stroma. This monolayer is central in the pathogenesis of Fuchs endothelial corneal dystrophy (FECD). FECD is a common corneal disease, in which corneal endothelial cells deposit extracellular matrix that increases the thickness of its basal membrane (Descemet's membrane), and forms excrescences (guttae). With time, there is a decrease in endothelial cell density that generates vision loss. Transplantation of a monolayer of healthy corneal endothelial cells on a Descemet membrane substitute could become an interesting alternative for the treatment of this pathology. In the back of the eye, the retinal pigment epithelium (RPE) forms the blood-retinal barrier, controlling fluid exchange between the choriocapillaris and the photoreceptors of the outer retina. In the retinal disease dry age-related macular degeneration (dry AMD), deposits (drusen) form between the RPE and its basal membrane (Bruch's membrane). These deposits hinder fluid exchange, resulting in progressive RPE cell death, which in turn generates photoreceptor cell death, and vision loss. Transplantation of a RPE monolayer on a Bruch's membrane/choroidal stromal substitute to replace the RPE before photoreceptor cell death could become a treatment alternative for this eye disease. This review will present the different biomaterials that are proposed for the engineering of a monolayer of corneal endothelium for the treatment of FECD, and a RPE monolayer for the treatment of dry AMD.

Identifying predictive factors for long-term visual recovery after corneal endothelial keratoplasty in Fuchs' dystrophy: Potential interaction between the corneal dysfunction and retinal status

Introduction

Descemet membrane endothelial keratoplasty (DMEK) is the main treatment for Fuchs' dystrophy (FECD). The outcomes are excellent, but the final visual recovery may vary from patient to patient with sometimes no obvious reason of such a spread.

Methods

We conducted a clinical prospective multicentric study to identify the predictive factors for the visual result 1 year after surgery. Eighty three patients (83 eyes) were included.

Results

Postoperative BCVA after 1 year was 0.20 ± 0.18 logMAR. Logistic regression revealed that good visual recovery correlated negatively with preoperative central macular thickness (p &lt; 0.001) and the need for rebubbling (p = 0.05), and positively with preoperative visual acuity (p = 0.009). Multivariate formula to predict the 1-year BCVA has been suggested.

Discussion

Preoperative retinal status seems to be the main predictive factor for long-term visual result after DMEK. Our predictive multivariate model could assist in better informing the patient about the prognosis of the surgery, and in adjusting the therapeutic strategy also, further highlighting the essential collaboration between both cornea and retina subspecialists.

Ability of routinely collected clinical factors to predict good visual results after primary Descemet membrane endothelial keratoplasty: a cohort study

Background

A comprehensive analysis of routinely collected pre/perioperative demographic/clinical factors that could predict final visual acuity after primary Descemet membrane endothelial keratoplasty (DMEK) has not been conducted previously.

Methods

A retrospective monocenter cohort study was performed with consecutive patients with Fuchs endothelial corneal dystrophy (FECD) who underwent DMEK or triple-DMEK (DMEK combined with cataract surgery) in 2016–2020 in a French tertiary-care hospital. DMEK-only patients were pseudophakic. Patients were followed for 12 months. Surgery was considered successful when 12-month best-corrected visual acuity (BCVA) was ≤0.1 logMAR (≥0.8). Exploratory multivariate analysis was conducted with the following routinely collected variables to determine their ability to predict 12-month BCVA: patient age and sex; graft donor age; triple DMEK; preoperative values of BCVA, endothelial cell density (ECD), central corneal thickness (CCT), and mean anterior keratometry; and rebubbling.

Results

Of 100 eyes (100 patients; mean age, 72 years; 61% female), 81 achieved a 12-month BCVA of ≤0.1 logMAR. Logistic regression analysis showed that older age was a significant prognosticator for 12-month BCVA > 0.1 logMAR (Odds Ratio = 0.914, 95% confidence intervals = 0.846–0.987; p = 0.02).

Conclusions

An older age associated with worse visual acuity outcomes after DMEK. This was confirmed by our analysis of the literature and supports the notion that DMEK should be conducted without delay once symptoms appear. Patient sex, donor age, triple-DMEK, and anterior keratometry also did not predict final BCVA in the literature. Preoperative CCT, ECD, and BCVA, and rebubbling occasionally appear in the literature as BCVA predictors, possibly reflecting an underlying ECD-BCVA axis.

Analysis of Corneal Scheimpflug Densitometry and Ocular Wavefront Aberrations Post Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

To assess the role of corneal densitometry and wavefront aberrations post Descemet stripping automated endothelial keratoplasty (DSAEK) and their correlation with visual acuity.

METHODS

Twenty-seven eyes of 25 patients with nonresolving corneal edema for more than 3 months as a result of Fuchs endothelial corneal dystrophy, pseudophakic bullous keratopathy, or secondary endothelial dysfunction were enrolled in a prospective interventional study and underwent DSAEK. Postoperative evaluation for corneal aberrations, including Higher order aberrations (HOAs) and corneal densitometry (CD), was performed using anterior-segment optical coherence tomography (Avanti RTvue XR; Optovue) and Scheimpflug imaging (Pentacam, Oculus Optikgeräte GmbH, Wetzlar, Germany) at 6 months. A correlation analysis of corneal aberrations, including HOAs and CD, with postoperative best-corrected visual acuity at 6 months was performed.

RESULTS

Mean best-corrected visual acuity (BCVA) improved from 1.67±0.53 log of minimum angle of resolution (logMAR) to 0.2±0.22 logMAR post DSAEK at 6 months (P≤0.0001). At 6 months, mean root-mean-square (RMS) total corneal aberrations (includes HOA and low-order aberration [LOA]), RMS total HOA, and RMS LOA of the central 6-mm zone were 4.99±2.64, 1.80±0.9, and 4.55±2.64, respectively. The mean corneal densitometry from anterior, central, and posterior zones were 39.12±12.77, 23.9±7.2, and 13.54±2.04 gray scale units, respectively. Total anterior aberrations (r=0.051; P=0.006), anterior LOA (r=0.049; P=0.009), total corneal aberrations (r=0.051; P=0.001), total HOAs (r=0.095; P=0.057) and LOAs (r=0.050; P=0.002), and total CD from 0 to 2 mm (r=0.010; P=0.038) and 2 to 6 mm (r=0.014; P=0.018) showed a significant inverse correlation with postoperative BCVA.

CONCLUSION

There was an inverse relationship between post DSAEK BCVA and total corneal HOAs and full-thickness densitometry at 6 months. Scheimpflug imaging with added tools for corneal aberration and densitometry analysis gives further insight into the suboptimal vision achieved despite transparent corneas post DSAEK.

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.

Five-year follow-up of corneal morphology and corneal refractive power changes after uneventful DMEK

PURPOSE

To investigate changes of corneal thickness spatial profile (CTSP), corneal volume (CV) distribution, and total corneal refractive power (TCRP) over a course of 60 months after uneventful Descemet membrane endothelial keratoplasty (DMEK).

METHODS

In our prospective, comparative study, sixty DMEK cases without intraoperative and postoperative complications and with complete 60-month follow-up were included (group 1). CTSP at corneal apex (CCT) and at 2 mm, 4 mm, 6 mm, and 8 mm rings, CV in 3 mm, 5 mm, 7 mm, and 10 mm zones, and TCRF in 2 mm, 4 mm 6 mm, and 8 mm zones were evaluated preoperatively and at 3, 6, 12, 24, and 60 months postoperatively. The 60-month results were compared to an age-matched group of uncomplicated pseudophakic eyes (group 2; n = 20).

RESULTS

The CCT and CTSP at 2, 4, and 6 mm increased significantly at 60 months compared to 3-month outcomes (P < 0.001). Similarly, CV increased significantly in 3 mm, 5 mm, and 7 mm zones at 60 months compared to 3 months outcomes (P < 0.001). The TCRP showed in all zones a significant decrease at 3 months (P < 0.001) followed by a continuous and significant increase at 60 months (P < 0.001). The 60-month CCT and CTSP at 2 mm were similar to group 2 (P ≥ 0.094).

CONCLUSION

Sixty months after uneventful DMEK, CT within the central 2 mm zone and CV at 3 mm zone were similar to uncomplicated pseudophakic eyes. A continuous and statistically significant increase of TCRP was observed in all measured zones after the 3-month examination.

Secondary Endothelial Keratoplasty-A Narrative Review of the Outcomes of Secondary Corneal Endothelial Allografts

BACKGROUND

We review the literature on the efficacy and safety outcomes of secondary Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Literature search of English-written publications up to September 27, 2020 in PubMed database, using the terms "endothelial keratoplasty" in combination with keywords "secondary" or "repeat." In addition, we manually searched the references of the primary articles.

RESULTS

Twenty-seven studies (n = 651 eyes) were retained and reviewed, including 10 studies on repeat DSEK, 8 studies on repeat DMEK, 6 studies of DMEK following DSEK, and 3 studies of DSEK after failed DMEK. All studies reported significant improvement in visual acuity after secondary endothelial keratoplasty (EK). Twelve studies compared visual outcomes between primary and secondary EK, reporting conflicting findings. Sixteen studies reported endothelial cell loss rates after secondary EK, and only 1 study reported significantly increased endothelial cell loss rates compared with primary EK. Allograft rejection episodes occurred in 1.8% of eyes (range, 0%-50%). Six studies compared complication rates between primary and secondary EK eyes, and only 1 study found a higher median number of complications. However, 2 studies reported higher regraft failure rates compared with primary EK eyes.

CONCLUSIONS

Secondary EK is surgically feasible and renders significant visual improvement after failed primary EK, although it is not clear whether visual outcomes and allograft survival are comparable with primary EK, raising the question of whether secondary EK eyes are "low risk" as primary EK eyes. Further larger, prospective studies are encouraged to obtain additional quality data on secondary corneal endothelial allotransplantation.

Corneal Densitometry After Uneventful Descemet Membrane Endothelial Keratoplasty-5-Year Outcomes

PURPOSE

The purpose of this study is to analyze the course of corneal densitometry (CD), endothelial cell density (ECD), best-corrected visual acuity (BCVA), and central corneal thickness (CCT) 5 years after uneventful Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Sixty uneventful cases (51 patients) with a minimum follow-up of 5 years were included. CD of various corneal layers (anterior, central, posterior, and total layer) and zones (0-2 mm, 2-6 mm, and 6-10 mm) were measured with Scheimpflug tomography. ECD, BCVA, and CCT were also evaluated.

RESULTS

Total CD at 0 to 2 mm and 2 to 6 mm zones significantly decreased from 33 ± 10 and 27.8 ± 8 grayscale units (GSU) preoperatively to 21.8 ± 3.1 and 22.2 ± 4.2 GSU at 5 years, respectively (P < 0.001). On the contrary, total CD at the 6 to 10 mm zone significantly increased from 30 ± 8.3 GSU preoperatively to 34.6 ± 7.8 GSU at 5 years (P < 0.001). ECD significantly decreased from 2496 ± 267 cells/mm2 preoperatively to 1063 ± 470 cells/mm2 at 5 years (P < 0.001). Similarly, CCT significantly decreased from 686 ± 109 μm preoperatively to 557 ± 37 μm at 5 years (P < 0.001). Postoperative BCVA was significantly better after DMEK for every examination time point.

CONCLUSIONS

Despite a slight CD increase at all layers of all corneal zones from the second to the fifth postoperative year, the excellent visual outcome was maintained throughout 5-year follow-up. Thus, DMEK seems to effectively treat corneal endothelial disease in the long term.

Focus on cell therapy to treat corneal endothelial diseases

The cornea is a multi-layered structure which allows fine refraction and provides both resistance to external insults and adequate transparency. The corneal endothelium ensures stromal hydration, failure of which, such as in Fuchs endothelial corneal dystrophy, after trauma or in aging, may lead to loss of corneal transparency and induce blindness. Currently, no efficient therapeutic alternatives exist except for corneal grafting. Thus corneal tissue engineering represents a valuable alternative approach, which may overcome cornea donor shortage. Several studies describe protocols to isolate, differentiate, and cultivate corneal endothelial cells (CEnCs) in vitro. Two main in vitro strategies can be described: expansion of eye-native cell populations, such as CEnCs, or the production and expansion of CEnCs from non-eye native cell populations, such as induced Pluripotent Stem Cells (iPSCs). The challenge with these cells is to obtain a monolayer of CEnCs on a biocompatible carrier, with a specific morphology (flat hexagonal cells), and with specific functions such as programmed cell cycle arrest. Another issue for this cell culture methodology is to define the adapted protocol (media, trophic factors, timeframe) that can mimic physiological development. Additionally, contamination by other cell types still represents a huge problem. Thus, purification methods, such as Fluorescence Activated Cell Sorting (FACS), Magnetic Ativated Cell Sorting (MACS) or Sedimentation Field Flow Fractionation (SdFFF) are useful. Animal models are also crucial to provide a translational approach for these therapies, integrating macro- and microenvironment influences, systemic hormonal or immune responses, and exogenous interactions. Non-eye native cell graft protocols are constantly improving both in efficacy and safety, with the aim of being the most suitable candidate for corneal therapies in future routine practice. The aim of this work is to review these different aspects with a special focus on issues facing CEnC culture in vitro, and to highlight animal graft models adapted to screen the efficacy of these different protocols.

Deep Learning for Assessing the Corneal Endothelium from Specular Microscopy Images up to 1 Year after Ultrathin-DSAEK Surgery

Purpose

To present a fully automatic method to estimate the corneal endothelium parameters from specular microscopy images and to use it to study a one-year follow-up after ultrathin Descemet stripping automated endothelial keratoplasty.

Methods

We analyzed 383 post ultrathin Descemet stripping automated endothelial keratoplasty images from 41 eyes acquired with a Topcon SP-1P specular microscope at 1, 3, 6, and 12 months after surgery. The estimated parameters were endothelial cell density (ECD), coefficient of variation (CV), and hexagonality (HEX). Manual segmentation was performed in all images.

Results

Our method provided an estimate for ECD, CV, and HEX in 98.4% of the images, whereas Topcon's software had a success rate of 71.5% for ECD/CV and 30.5% for HEX. For the images with estimates, the percentage error in our method was 2.5% for ECD, 5.7% for CV, and 5.7% for HEX, whereas Topcon's software provided an error of 7.5% for ECD, 17.5% for CV, and 18.3% for HEX. Our method was significantly better than Topcon's (P < 0.0001) and was not statistically significantly different from the manual assessments (P > 0.05). At month 12, the subjects presented an average ECD = 1377 ± 483 [cells/mm2], CV = 26.1 ± 5.7 [%], and HEX = 58.1 ± 7.1 [%].

Conclusions

The proposed method obtains reliable and accurate estimations even in challenging specular images of pathologic corneas.

Translational Relevance

CV and HEX, not currently used in the clinic owing to a lack of reliability in automatic methods, are useful biomarkers to analyze the postoperative healing process. Our accurate estimations allow now for their clinical use.

Ultrathin Descemet stripping automated endothelial keratoplasty versus Descemet membrane endothelial keratoplasty: a fellow-eye comparison

Background

To compare the visual outcome and patients’ satisfaction after ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) performed on fellow eyes of the same patients.

Methods

In this retrospective study, the records of 18 pseudophakic patients affected by Fuchs endothelial dystrophy who underwent DMEK in one eye and UT-DSAEK in the fellow eye were reviewed. Best corrected visual acuity (BCVA), corneal pachymetry, keratometry, corneal aberrations, photopic and mesopic contrast sensitivity, and endothelial cell counts measured 12 months after surgery in either eye were analyzed and compared. The results of a satisfaction questionnaire were also reviewed.

Results

Twelve months after surgery, BCVA was not significantly different in UT-DSAEK and DMEK eyes (0.10 ± 0.04 and 0.07 ± 0.07 logMAR, respectively); at both 4- and 6 mm optical zones total and posterior corneal higher order aberrations (HOAs), posterior astigmatism and total coma were significantly lower after DMEK; BCVA in both groups was significantly correlated mainly with anterior corneal aberrations; contrast sensitivity was higher after DMEK especially in mesopic conditions and at medium spatial frequencies; the endothelial cell density was similar, although slightly higher in the UT-DSAEK group (p = 0.10). The satisfaction questionnaire showed that although patients were highly satisfied from both procedures, more than half of them preferred DMEK and reported a more comfortable and quicker postoperative recovery.

Conclusions

DMEK and UT-DSAEK showed no evidence of difference in terms of postoperative BCVA, although DMEK had a better performance in terms of contrast sensitivity, posterior corneal aberrations and overall patient satisfaction.

Modified thin manual Descemet stripping endothelial keratoplasty with air-guided, non-pachymetric donor lenticule dissection: outcomes of graft thickness and complication rate

AIM

To describe a modified technique of donor lenticule dissection for thin manual Descemet stripping endothelial keratoplasty (TM-DSEK).

METHODS

Donor material was soaked in balanced salt solution (BSS) for 30min, before being mounted on an artificial anterior chamber (AAC). Rather than BSS, the AAC was filled with filtered air, resulting in a visible reflection at the corneal endothelium-air interface. This reflection served as a landmark for the depth of the dissection, facilitating the creation of a thin lenticule with low risk of perforation. Dissection was commenced at a standardized depth of 500 microns, with no initial pachymetry necessary. Totally 29 donor corneas were dissected by a novice TM-DSEK surgeon. Dissection time, central graft thickness at 2mo and complications were analysed.

RESULTS

Results were similar to other endothelial keratoplasty techniques, despite the cases being performed by a novice DSEK surgeon. Mean dissection time was 7min (range 6-10). One graft perforation occurred (3.45%), but the air tamponaded the break and enabled dissection to be restarted and completed from a different location. Mean central graft thickness after at least two months follow-up was 106 microns (range 25-170).

CONCLUSION

A problem with manual DSEK is the risk of graft perforation by attempting to dissect too thin a lenticule, or creating a thick graft due to fear of perforating. This modified air-guided technique addresses this problem, and is recommended for surgeons either embarking on the learning curve, or who wish to achieve more consistently thin grafts while reducing perforation rates.

Descemet Membrane Endothelial Keratoplasty Versus Descemet Stripping Automated Endothelial Keratoplasty and Penetrating Keratoplasty

PURPOSE

To compare the long-term graft survival outcomes and complications of patients who underwent Descemet membrane endothelial keratoplasty (DMEK), Descemet stripping automated endothelial keratoplasty (DSAEK), and penetrating keratoplasty (PK) for Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK).

DESIGN

Retrospective comparative cohort study.

METHODS

Patients with FECD and BK who underwent DMEK (121 eyes), DSAEK (423 eyes), or PK (405 eyes) from the prospective cohort from the Singapore Corneal Transplant Registry were included. A Kaplan-Meier survival analysis was conducted to compare the survival probabilities of the 3 groups. The main outcome measure was graft survival.

RESULTS

The DMEK group had the best overall cumulative graft survival of 97.4%, compared to DSAEK (78.4%) and PK (54.6%) (P < .001). In eyes with FECD, the DMEK group had the best graft survival of 98.7% compared to DSAEK (96.2%) and PK (73.5%) (P = .009). The graft survival in eyes with BK was poorer overall; however, the DMEK group still had the best graft survival of 94.7%, compared to DSAEK (65.1%) and PK (47.0%, P = .001). Eyes that underwent DMEK had the lowest rate of graft rejection (1.7% vs DSAEK 5.0% vs PK 14.1%, P < .001) and postoperative elevation of intraocular pressure (11.6% vs DSAEK 23.6% vs PK 22.5%, P = .015).

CONCLUSIONS

Patients who underwent DMEK for FECD and BK had better graft survival compared to DSAEK and PK. Eyes that underwent DMEK also had a significantly lower rate of graft rejection and elevated intraocular pressure compared to DSAEK and PK for the same indications.

Outcome of Descemet membrane endothelial keratoplasty for graft failure after Descemet stripping automated endothelial keratoplasty

Purpose

To investigate the efficacy and safety of Descemet membrane endothelial keratoplasty (DMEK) for corneal decompensation following primary Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods

This was a retrospective case series of 15 patients that underwent DMEK surgery for corneal decompensation after failed DSAEK. Main outcome parameter was corrected distance visual acuity (CDVA) after DMEK and DSAEK. Secondary outcome measures included central corneal thickness (CCT), endothelial cell density (ECD), rebubbling rate, and primary graft failure after DMEK. Explanted DSAEK grafts were evaluated by light microscopy.

Results

The mean (±SD) time period between DSAEK and DMEK surgery was 15±8 months (range, 6–31 months). Preoperative CDVA was 1.72±0.62 (logMAR). After DMEK, CDVA improved significantly to 0.78±0.48 at 1 month and to 0.23±0.24 after 12 months (P=0.022). Visual acuity data after DMEK were significantly better compared to preoperative values. The average CCT after DMEK decreased significantly from 869±210 µm (preoperative) to 505±45 µm (1 month postoperative) (P<0.001) and remained stable over 12 months. The ECD decreased from 2,589±209/mm² (preoperative) to 1,691±589/mm² (12 months postoperative). Rebubbling DMEK was required in three patients (=20%).

Conclusion

DMEK represents a feasible and safe procedure in achieving better functional results compared to DSAEK. Visual acuity and optical quality can be effectively reestablished after unsuccessful primary DSAEK surgery even in patients with long-standing corneal decompensation. Further investigations are required to validate the preliminary clinical findings.

Functional outcome of repeat Descemet membrane endothelial keratoplasty (DMEK) for corneal decompensation following graft failure after primary DMEK

Purpose

To evaluate if repeat Descemet membrane endothelial keratoplasty (DMEK) is appropriate to achieve functional improvements in patients with corneal decompensation from secondary graft failure after primary DMEK.

Methods

This is a retrospective monocentric cohort study including 13 eyes of 13 patients with repeat DMEK for corneal decompensation following primary DMEK. Eyes with primary DMEK only and comparable preoperative corrected distance visual acuity (CDVA) served as control. Main outcome parameter was CDVA. Secondary outcome measures were central corneal thickness (CCT), endothelial cell density, and rebubbling rate (RR).

Results

The average time interval (±SD) between primary and secondary DMEK was 12.5±6 months. Preoperative CDVA (logMAR) was 1.97±0.90 in the repeat DMEK group and 1.38±0.92 in the primary DMEK group. At 6 months, both groups showed significant improvement in visual acuity (repeat DMEK group, 0.49±0.35, P<0.01 and primary DMEK group, 0.40±0.36, P<0.01). CDVA did not differ significantly between both groups at all time points examined (1, 3, and 6 months postoperatively). Mean CCT values at 3 and 6 months postoperatively did not differ significantly between the two groups (P>0.05). The RR was 23% (n=3) in both groups.

Conclusion

Repeat DMEK is a useful therapeutic approach in the setting of corneal decompensation following primary DMEK. Functional results of repeat DMEK, visual acuity in particular, are comparable to patients with single DMEK only.

Cost-Effectiveness Analysis of Descemet's Membrane Endothelial Keratoplasty Versus Descemet's Stripping Endothelial Keratoplasty in the United States

PURPOSE

To determine the cost-effectiveness of Descemet's membrane endothelial keratoplasty (DMEK) compared with Descemet's stripping automated endothelial keratoplasty (DSAEK) in the United States.

DESIGN

Cost-effectiveness analysis in a surgical center in the United States.

PARTICIPANTS

Binocular adult patient undergoing endothelial keratoplasty.

METHODS

A base case of a 70-year-old man undergoing his first endothelial keratoplasty for bilateral Fuchs endothelial dystrophy. The cost-effectiveness of DMEK was compared with DSAEK over a 15-year time horizon. The incidences and costs of complications were derived from PubMed English literature searches, Medicare reimbursements, and average wholesale prices. All costs were discounted 3% per annum and adjusted for inflation to 2018 U.S. dollars. Uncertainty was evaluated using deterministic and probabilistic sensitivity analyses.

MAIN OUTCOME MEASURES

Incremental cost-effectiveness ratios and incremental cost-utility ratios, measured in cost per quality-adjusted life-years (QALYs).

RESULTS

Performing a DMEK instead of a DSAEK generated an extra 0.4 QALYs over a 15-year period. From a societal and third-party payer perspective, DMEK was cost-saving when compared with DSAEK in improving visual acuity in the base case. Probabilistic sensitivity analyses with variations in the costs and rebubble rates revealed that DMEK was cost-saving compared with DSAEK in 38% of iterations and was within a societal willingness-to-pay threshold of $50 000 in 98% of models.

CONCLUSIONS

From the societal and third-party payer perspectives in the United States, DMEK generated greater utilities and was less costly than DSAEK. Therefore, DMEK was the dominant procedure and was cost-saving with respect to DSAEK. The economic model was robust based on sensitivity analyses.

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.

Visual outcome of penetrating keratoplasty, deep anterior lamellar keratoplasty and Descemet membrane endothelial keratoplasty

PURPOSE

A single-center, cross-sectional study was designed to assess and compare objective and subjective quality of vision of patients intervened with penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Forty-six patients previously intervened with PK (22 eyes), DALK (7 eyes) and DMEK (17 eyes) were recruited. Visual evaluation included spherical and cylindrical refraction, distance corrected visual acuity (DCVA), photopic contrast sensitivity (CS), optical quality, measured with the HD Analyzer (objective scattering index [OSI], MTF cut-off and Strehl ratio), and ocular and corneal aberrometry, measured with the KR-1W Wavefront Analyzer.

RESULTS

Statistically significant between-group differences were found in age (p=0.006, DMEK patients were older) and time since surgery (p<0.001, longest time for PK patients). No statistically significant differences were found in DCVA between the techniques. Between-group differences were encountered in CS at 12 (p=0.007) and 18 (p<0.001) cycles per degree, with DMEK and DALK obtaining the best and worst outcomes, respectively. Differences in optical quality were found between the techniques (OSI, p=0.004; MTF cut-off, p=0.048; Strehl ratio p=0.022), with DMEK displaying the best outcomes. Highest and lowest values in ocular and corneal aberrations were for DALK and DMEK patients, respectively. Between-group differences were found in corneal astigmatism (p<0.001; -3.31±2.00 D in PK; -2.68±0.94 D in DALK; -1.09±0.62 D in DMEK).

CONCLUSION

Overall, DMEK proved superior over PK and DALK in terms of quality of vision, with PK offering slightly better outcomes than DALK in most visual function parameters under evaluation.

Scheimpflug Densitometry After DMEK Versus DSAEK-Two-Year Outcomes

PURPOSE

To compare the course of Scheimpflug corneal densitometry (CD) after Descemet membrane endothelial keratoplasty (DMEK) versus Descemet stripping automated endothelial keratoplasty (DSAEK).

METHODS

Fifty-four DMEK and 25 DSAEK cases without previous corneal surgery, complicated intraoperative or postoperative course, or vision-limiting ocular comorbidities were included. Pseudophakic eyes of age-matched subjects were recruited as controls (n = 20). Scheimpflug CD of the optically relevant zones (0-2 and 2-6 mm), best-corrected visual acuity (BCVA), endothelial cell density, and central corneal thickness were evaluated preoperatively and at 3, 6, 12, and 24 months postoperatively.

RESULTS

CD of the optical zone decreased from 34.4 ± 9.4 grayscale units (GSU) before to 19.2 ± 2.7 GSU at 24 months after DMEK. Respectively, CD decreased from 34.0 ± 13.4 GSU before to 21.2 ± 2.5 GSU at 24 months after DSAEK. Mean central CD in group 3 was 18.1 ± 1.3 GSU. Compared with DSAEK, DMEK cases showed lower central CD at 3 and 6 months (P ≤ 0.012) but not at 12 and 24 months postoperatively. DSAEK showed higher CD values throughout the postoperative period compared with healthy controls (P < 0.001). DMEK showed higher CD compared with controls at 3, 6, and 12 but not at 24 months after surgery (P = 0.152). Postoperative BCVA was significantly better after DMEK for every examination time point. No difference in endothelial cell density was found between DMEK and DSAEK at any time point.

CONCLUSIONS

DMEK showed lower CD and better BCVA compared with DSAEK in the first 6 postoperative months. Notably, although CD reached similar levels in the midterm after both DMEK and DSAEK, BCVA remained significantly better after DMEK.

Factors Limiting the Visual Outcome After Descemet Stripping Automated Endothelial Keratoplasty: Comprehensive Analysis Including the Graft Position and Irregularity

PURPOSE

To investigate factors affecting best postoperative corrected distance visual acuity (CDVA) in patients who have undergone Descemet stripping automated endothelial keratoplasty (DSAEK).

METHODS

Forty-two eyes of 42 patients with predominantly non-Fuchs endothelial corneal dystrophy after DSAEK were retrospectively evaluated. All patients were examined using anterior segment optical coherence tomography when their best postoperative CDVA had been achieved. We analyzed the relationship between best postoperative CDVA and preoperative, intraoperative, and postoperative factors, including corneal higher-order aberrations (HOAs), corneal backward scattering, graft irregularity, and graft decentration. Variables with P < 0.2 in univariate analysis were entered into a multivariate linear regression model to determine the factors affecting best postoperative CDVA.

RESULTS

Mean CDVA improved from 1.16 ± 0.46 preoperatively to 0.22 ± 0.19 logarithm of the minimum angle of resolution equivalents postoperatively (P < 0.0001). Best postoperative CDVA was achieved 11.6 ± 7.7 months after DSAEK. Multivariate analysis showed that anterior corneal coma-like HOAs and venting incisions inside the pupil area were significantly correlated with best postoperative CDVA (t = 2.90, P = 0.006; t = 2.62, P = 0.01, respectively). No significant relationship was found between the visual outcome and any other factor, including posterior corneal HOAs, corneal backward scattering, graft decentration, and graft irregularity.

CONCLUSIONS

Irregularity of the anterior corneal surface and venting incisions inside the pupil area are important factors that impair best postoperative CDVA in patients who have undergone DSAEK. In contrast, our results indicate that the graft position and irregularity might not have a strong influence on the visual outcome after DSAEK.

Visual outcomes following Descemet stripping automated endothelial keratoplasty for corneal endothelial dysfunction

OBJECTIVE

To assess objective and subjective visual outcomes achieved by patients with corneal endothelial dysfunction who have undergone surgical treatment with Descemet stripping automated endothelial keratoplasty (DSAEK).

METHODS

A total of 40 eyes of 36 patients with corneal endothelial dysfunction underwent DSAEK. All were followed up for 1 year. Visual acuity (VA; logMAR), mean endothelial cell density (MCD; via noncontact specular microscopy), and topography assessment were performed at baseline (preoperatively). Visual acuity and topography measurement were repeated at postoperative year 1. Subjective assessment of visual quality was evaluated using the National Eye Institute Visual Function Questionnaire (NEI-VFQ).

RESULTS

Preoperative best-corrected VA (BCVA) was 1.29 ± 0.53 logMAR with mean optical correction of -0.33 ± 1.74 D. Postoperative BCVA, assessed after a mean of 10.8 ± 2.1 months, showed mean line gain of 7.11 ± 4.8 logMAR, with optical correction of +1.17 ± 1.54 D. Mean 6-month postoperative pachymetry was 598.2 ± 72.3 µm. Three patients experienced premature graft detachment, requiring repositioning via injection of a sterile air bubble. No other adverse events were observed. Significant improvement (p<.05 for all) in general, near, and far vision, ocular pain, difficulty in carrying out daily tasks, dependency, social life, and mental health were reflected by NEI-VFQ scores at 10.4 ± 2.1 months postoperatively versus preoperatively. No significant correlation was noted between postoperative VA line gain and NEI-VFQ-25 questionnaire score (p>0.05).

CONCLUSIONS

Descemet stripping automated endothelial keratoplasty treatment may restore corneal clarity, improve VA, and increase vision-related quality of life in patients with advanced endothelial dysfunction. Further large-scale study is needed to corroborate these findings.

A review of the evidence for in vivo corneal endothelial regeneration

Human corneal endothelium has long been thought to be a nonmitotic cell layer with no endogenous reparative potential. Pathologies that damage endothelial function result in corneal decompensation and, if untreated, blindness. The mainstay of treatment involves partial or complete corneal replacement, amounting to 40% of all corneal transplants performed worldwide. We summarize the case reports describing complications postoperatively in the form of (sub)total graft detachment and those resulting in postoperative bare stroma. Complications during cataract and glaucoma surgeries leading to an uncovered posterior cornea are also included. We discuss the newer treatment strategies that are alternatives for current Descemet membrane endothelial keratoplasty and Descemet stripping automated endothelial keratoplasty, including partial grafts and stripping of the diseased cell layer. In more than half of the cases reviewed, corneal transparency returned despite incomplete or no corneal endothelial cell transplantation. We question the existing paradigm concerning corneal endothelial wound healing in vivo. The data support further clinical study to determine the safety of simple descemethorexis in central endothelial pathologies, such as Fuchs endothelial corneal dystrophy, where presence of healthy peripheral cells may allow successful corneal recompensation without the need for donor cells.

Descemet stripping automated endothelial keratoplasty versus descemet membrane endothelial keratoplasty: a meta-analysis

PURPOSE

To evaluate the efficacy and safety of descemet stripping automated endothelial keratoplasty (DSAEK) compared with descemet membrane endothelial keratoplasty (DMEK).

METHODS

Databases including PubMed, EMBASE, and Cochrane Library were searched to find studies that compared DSAEK and DMEK outcomes. Efficacy parameters were the postoperative best-corrected visual acuity (BCVA) and spherical equivalent (SE). Safety parameters were postoperative endothelial cell loss (ECL), air injection (rebubbling), graft failure, graft rejection, and high intraocular pressure (IOP). Results from last visit were pooled for the analyses because the follow-up ranged from 3 to 24 months.

RESULTS

A total of 7 trials including 433 eyes were selected for this meta-analysis. BCVA was reported in all 7 studies, ECL% and rebubbling rate were reported in 6, and the remaining outcomes were reported in only 3 or 2 studies. Postoperative logMAR BCVA was significantly better for DMEK than that for DSAEK (P < 0.00001). More patients achieved the postoperative BCVA ≥ 20/25 and 20/20 in DMEK group than that in DSAEK (P > 0.001), whereas the proportion of patients whose postoperative BCVA ≥ 20/40 and the amount of SE did not differ statistically (P = 0.32 and P = 0.50, respectively). The DSAEK group has a significantly lower frequency of rebubbling than the DMEK group (P < 0.0001). The postoperative ECL%, graft failure, graft rejection, and high IOP were comparable between the 2 groups (all P values >0.05).

CONCLUSIONS

Our meta-analysis suggests that DMEK provided better visual outcomes with similar safety when compared to DSAEK. Given the limited sample size, further investigations are needed to validate these findings.

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.

Long-Term Observation of Triplex Surgery for Cataract after Phakic 6H Implantation for Super High Myopia

Purpose. To analyze the safety, effectiveness, and stability of triplex surgery for phakic 6H anterior chamber phakic intraocular lens explantation and phacoemulsification with in-the-bag IOL implantation for super high myopia in long-term observations. Methods. This retrospective case series evaluated 16 eyes of 10 patients who underwent triplex surgery. Best corrected visual acuity (BCVA), endothelial cell density (ECD), and associated adverse events were evaluated. Results. The mean follow-up time after the triplex surgery was 46 ± 14 months. The mean logMAR BCVA was significantly improved after triplex surgery (P = 0.047). One eye developed endophthalmitis five days postoperatively and underwent pars plana vitrectomy (PPV). Five eyes with preoperative severe endothelial cell loss developed corneal decompensation and underwent keratoplasty at a mean time of 9.4 ± 2.6 months after the triplex surgery. One eye had graft failure and underwent a second keratoplasty. The eye developed rhegmatogenous retinal detachment and underwent PPV with silicone oil 18 months later. ECD before the triplex surgery was not significantly different compared with that at last follow-up (P = 0.495) apart from these five eyes. Three eyes (18.8%) developed posterior capsule opacification. Conclusions. Triplex surgery was safe and effective for phakic 6H related complicated cataracts. Early extraction before severe ECD loss is recommended.