Descemet stripping endothelial keratoplasty--rapid recovery of visual acuity

Kataraktoperation beim Vorliegen einer Fuchs-Endotheldystrophie

Bei Betroffenen mit einer Fuchs-Endotheldystrophie beginnen die Probleme mit den Augen häufig in einem Alter, in dem sich auch schon erste Anzeichen einer Katarakt zeigen. Und umgekehrt findet man in der augenärztlichen Praxis immer wieder Patient*innen mit einer deutlichen Katarakt und einer Cornea guttata als Nebenbefund. In beiden Situationen stellt sich dann die Frage, ob zunächst nur eine posteriore lamelläre Keratoplastik (in Deutschland meist als DMEK) bzw. nur eine Kataraktoperation erfolgen oder ob gleich ein kombiniertes Vorgehen (sog. Triple-Operation) angestrebt werden sollte. Nur bei jungen Betroffenen mit einer fortgeschrittenen Fuchs-Endotheldystrophie ohne jeglichen Hinweis auf eine Katarakt und gut erhaltener Akkommodation kann, je nach individuellen Gegebenheiten, eine alleinige DMEK sinnvoll sein, in allen anderen Fällen erscheint eine Triple-Operation geeigneter. Dabei erscheint ein sequenzielles Vorgehen in diesen Situationen weniger angebracht, da sich in zahlreichen Studien zeigte, dass der Verlauf und die Ergebnisse nach einer Triple-Operation mit denen nach einem sequenziellen Vorgehen vergleichbar sind. Beim Vorliegen einer signifikanten Katarakt und einer Cornea guttata fällt die Entscheidung im Hinblick auf das operative Vorgehen deutlich schwerer. Hierbei gibt es unterschiedliche Aspekte in der Anamnese sowie den ophthalmologischen Untersuchungen (z. B. zentrale Hornhautdicke, Endothelzelldichte), die einem bei der Entscheidung helfen können. Soll dann zunächst nur eine Kataraktoperation erfolgen, sollten geeignete Maßnahmen ergriffen werden, um ein möglichst optimales Ergebnis trotz Vorliegen der Cornea guttata zu erreichen. Im folgenden Beitrag soll auf die wichtigsten prä-, peri- und postoperativen Aspekte im Hinblick auf die bestmögliche operative Versorgung von Betroffenen mit Fuchs-Endotheldystrophie und Katarakt eingegangen werden.

The Cologne-Mecklenburg-Vorpommern DMEK Donor Study (COMEDOS) - design and review of the influence of donor characteristics on Descemet membrane endothelial keratoplasty (DMEK) outcome

Background

Posterior lamellar keratoplasty and especially Descemet membrane endothelial keratoplasty (DMEK) are gaining interest worldwide. Little is known about the influence of donor factors on DMEK outcome. Here we provide an overview of the existing peer-reviewed literature on this topic and present the design of the upcoming cooperation study COMEDOS (Cologne-Mecklenburg-Vorpommern DMEK Donor Study).

Methods

A literature search of PubMed and MEDLINE was conducted to retrieve articles published between September 2013 and May 2021. Seventeen peer-reviewed articles were selected. Design and concept of the prospective COMEDOS are outlined.

Results

Main interest parameters were the donor diabetes mellitus status, age, and lens status. There is a large heterogeneity regarding the sample size, study design, and investigated parameters. There seems to be a consensus that younger donors are associated with tighter rolls, a more difficult preparation, and unfolding setting. Diabetic donors seem to increase the risk of tissue tearing due to adherences and result more frequently in preparation failure. The COMEDOS aims not only to analyze the diabetes status of the donor, but also to correlate all donor systemic comorbidities and their ophthalmologic history to the DMEK clinical outcome. Furthermore, a correlation of Descemet membrane lamella preparation and surgery outcome is planned.

Conclusion

Currently, there is a lack of knowledge regarding the effect and impact of donor tissue characteristics on DMEK outcome and complications. An in-depth investigation is planned by the upcoming COMEDOS to close this knowledge gap.

Comparative Analysis of Corneal Parameters in Swept-Source Imaging between DMEK and UT-DSAEK Eyes

Background: The need to provide a comparative analysis of corneal parameter changes compared to their preoperative values between Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) patients. Methods: The study included 24 eyes after UT-DSAEK and 24 eyes after DMEK. Visual acuity, endothelial cell count (ECC), central corneal thickness (CCT), mean keratometry (MK), mean astigmatism (MA), astigmatism asymmetry (AA) and higher-order aberrations (HOAs) were assessed at baseline and 1, 3, 6 and 12 months after the surgery. Results: From the 3rd month post operation, ECC was higher in the DMEK eyes than in the UT-DSAEK eyes (p = 0.01). In a bivariate analysis that was adjusted for age, DMEK was associated with a smaller decrease in posterior MK at the 1-month (β = −0.49, p = 0.002), 3-month (β = −0.50, p < 0.001), 6-month (β = −0.58, p < 0.001) and 12-month (β = −0.49, p < 0.001) follow-up visits. There were no significant differences in changes in anterior or combined surface MK throughout the observation period. Accordingly, no significant differences in changes in MA, AA or HOAs compared to the baseline values were identified between the eyes after DMEK and UT-DSAEK at any follow-up time point. Conclusions: UT-DSAEK seemed to be an easier and safer technique than DMEK while maintaining similar outcomes regarding irregular astigmatism and total keratometry values.

Changes in Corneal Parameters after DMEK Surgery: A Swept-Source Imaging Analysis at 12-Month Follow-Up Time

Purpose

To assess the time course changes in corneal topographic parameters during the one-year follow-up after Descemet membrane endothelial keratoplasty (DMEK) surgery.

Materials and Methods

Twenty-one patients (24 eyes) who underwent DMEK surgery were evaluated. Best corrected visual acuity (BCVA), endothelial cell count (ECC), central corneal thickness (CCT), mean keratometry (MK), mean astigmatism (MA), astigmatism asymmetry (AA), and higher-order aberration (HOA) were assessed at baseline and 1, 3, 6 and 12 months after the surgery using CASIA2 anterior segment swept-source OCT (Tomey, Japan).

Results

In patients who underwent DMEK surgery, BCVA improved gradually at the subsequent visits during the 12-month follow-up. A significant reduction in ECC and CCT at the 1st month was noted, which remained stable until the 6th month postoperatively. Anterior and total MK values remained unchanged, whereas changes in posterior keratometry were noticeable until the 6th month after surgery. A significant reduction in the anterior, posterior, and total astigmatism magnitude as well as astigmatism asymmetry was observed during the first 6 months after surgery. A gradual anterior, posterior, and total HOA decrease was documented until the 12th month after surgery. Negative correlations between baseline values of CCT, MK, MA, AA, and HOA and postoperative variations in those parameters at consecutive follow-up time points were observed. Accordingly, negative correlations between baseline CCT and postoperative changes in corneal topographic parameters after surgery were found.

Conclusion

The stabilization of most corneal topographic parameters takes place within 6 months after the procedure, whereas HOA reduction and BCVA improvement gradually occur during the first year after surgery. Preoperative values of corneal topographic parameters strongly determine their changes detected after DMEK surgery, which may suggest that early therapeutic intervention results in better visual outcomes.

[Descemet membrane endothelial keratoplasty (DMEK) for graft failure after penetrating keratoplasty and in vascularized high-risk eyes]

BACKGROUND

Descemet membrane endothelial keratoplasty (DMEK) is considered the gold standard for the treatment of corneal endothelial dysfunction and generally leads to good postoperative results. Recently, studies have also analyzed the outcome of DMEK in so-called high-risk eyes.

MATERIAL AND METHODS

The relevant literature and own data on DMEK for graft failure after penetrating keratoplasty and in vascularized high-risk eyes are presented and discussed.

RESULTS

A DMEK for the treatment of transplant failure after penetrating keratoplasty can be considered for eyes without stromal scars and without high astigmatism. A retrospective analysis of 52 patients with failed penetrating grafts showed that DMEK leads to a significant increase in visual acuity, albeit to a lesser extent than after primary DMEK. Rejection and transplant failure rates seem to be similar those seen after penetrating re-keratoplasty and are thus higher than after primary DMEK. A DMEK might also be a feasible option for eyes with corneal neovascularization and stromal edema without stromal scars. A retrospective analysis of 24 eyes with at least 2 vascularized corneal quadrants demonstrated that DMEK leads to a significant improvement in visual acuity and regression of corneal neovascularization. The rejection rate in this cohort was 4.2% and is therefore slightly higher than after low-risk DMEK in eyes without corneal neovascularization but still much better compared to penetrating keratoplasty.

CONCLUSION

Indications for DMEK are expanding and it can be a therapeutic option for transplant failure after penetrating keratoplasty with acceptable outcomes. Furthermore, DMEK seems to be a good option for the treatment of endothelial dysfunction in vascularized high-risk eyes without stromal scars.

Corneal transplantation activity in Catalonia, Spain, from 2011 to 2018: Evolution of indications and surgical techniques

Purpose

To report corneal transplant activity carried out in Catalonia (Spain) and the evolving indications for keratoplasty over an 8-year period.

Methods

Annual reports from the Catalan Transplant Organization, Spain, on corneal graft indications and techniques from 2011 to 2018 were reviewed.

Results

A total of 9457 keratoplasties were performed in Catalonia, from January 2011 to December 2018. The most frequent indications were bullous keratopathy (BK; 20.5%), Fuchs endothelial dystrophy (FED; 17.9%), re-graft (13.7%), and keratoconus (11.3%). Penetrating keratoplasty (PKP) accounted for 63.4% of all performed keratoplasties. Since the introduction of eye bank precut tissue for Descemet stripping automated endothelial keratoplasty (DSAEK) in 2013 and for Descemet membrane endothelial keratoplasty (DMEK) in 2017 the number of endothelial keratoplasties has drastically increased. An increasing trend of posterior lamellar techniques over the total of keratoplasties was found (p<0.001). Endothelial keratoplasties for different endothelial diseases indications (BK, FED, and re-graft), also showed and increasing trend (p<0.001). DMEK is the technique with the highest increase (statistically significantly different from linearity) over other endothelial keratoplasties in FED (p<0.001) but not in BK (p = 0.67) or re-grafts (p = 0.067).

Conclusion

Endothelial diseases represented the top indication for keratoplasty over the 8-year period. PKP is still the most used technique in Catalonia, but endothelial keratoplasties and especially DMEK showed a significant increasing trend over the last years. This is congruent with the main rationale nowadays for keratoplasties: to customize and transplant as less tissue as possible. Therefore, the availability of precut tissue could have definitely enforced such approach.

Descemet Membrane Endothelial Keratoplasty versus Descemet Stripping Automated Keratoplasty - Outcome of One Single Surgeon's More Than 200 Initial Consecutive Cases

Purpose

To compare clinical outcome and complications of Descemet stripping automated keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK).

Methods

This is a retrospective study of the first consecutive cases of DSAEK and DMEK performed by a single surgeon at a tertiary referral centre. Best-corrected visual acuity (BCVA), postoperative complications, rate of rebubbling and regraft were the main outcome measures.

Results

The study included 241 eyes, 116 subjected to DSAEK and 125 to DMEK. Fuchs endothelial dystrophy (FED) was the predominant diagnosis in both groups. Mean BCVA at all follow-ups up to 2 years was in favour of DMEK. Median BCVA (decimal) at 1 year was 0.4 (0.13–0.60; interquartile range) for the DSAEK and 0.8 (0.6–1.0) for the DMEK group, p<0.001. Preoperative BCVA in the DSAEK group was lower than in DMEK. There was no significant difference in visual improvement between groups at 1 year postoperatively. The most common postoperative complication in both groups was a pupillary block with high intraocular pressure, 27% and 34% respectively. This was not affected by the presence of an iridectomy/iridotomy. In the DMEK group, gas provided significantly better adherence than air (p=0.020). Rebubbling for partial/total detachment was performed in 7% (DSAEK) and 11% (DMEK) of cases, p=0.361. Regraft within 2 years was performed in 13% of eyes in the DSAEK and 17% in the DMEK group, p=0.450. No case of graft rejection occurred.

Conclusion

Both DSAEK and DMEK provide overall satisfying outcome and the two techniques do not differ significantly in postoperative pupillary block, detachment rate, early graft failure or graft rejection. However, differences at baseline may have influenced or obscured potential differences. In DMEK procedures, gas seems to facilitate early graft adherence.

Refractive outcomes following cataract combined with lamellar keratoplasty: femtosecond-DSEK versus microkeratome-DSAEK

PURPOSE

Prediction of postoperative refraction following posterior lamellar keratoplasty is crucial for choosing proper intraocular lens power in combined surgeries. Femtosecond laser-assisted Descemet stripping endothelial keratoplasty (FS-DSEK) creates thin, planar grafts while microkeratome-assisted Descemet's stripping automated endothelial keratoplasty (DSAEK) creates non-planar, concaved grafts. We evaluated whether this fundamental difference affects the refractive outcomes in cataract surgery combined with FS-DSEK compared to cataract surgery combined with microkeratome-assisted DSAEK.

METHODS

A retrospective analysis of 28 patients who underwent FS-DSEK combined with phacoemulsification and intraocular lens (IOL) implantation (group A) compared to 26 patients who underwent microkeratome-assisted DSAEK combined with phacoemulsification and IOL implantation (group B). Pre- and 1-year postoperative best-corrected visual acuity (BCVA), keratometry values, corneal thickness, central-to-peripheral graft thickness ratio (C/P ratio), and target postoperative spherical equivalent (SE) versus actual postoperative SE were analyzed.

RESULTS

Target postoperative SE and actual postoperative SE significantly shifted toward hyperopia in group B, but not in group A. Postoperative hyperopic shifts were 0.14 D and 1.13 D in groups A and B, respectively (P < 0.001). BCVA improved after surgery in both groups, with no significant difference between the groups. Postoperative C/P ratio differed significantly between the groups and was negatively correlated with postoperative hyperopic shift (r =  - 0.616, P < 0.001).

CONCLUSION

Refractive outcomes of cataract surgery combined with FS-DSEK are relatively neutral, whereas those of cataract surgery combined with microkeratome-assisted DSAEK cause significant hyperopic shift. Clinicians should select accordingly an appropriate intraocular lens power when performing these surgeries.

Comparative observation of the efficacy of simplified Descemet stripping endothelial keratoplasty and penetrating keratoplasty in treating bullous keratopathy

The aim of the present study was to compare the clinical efficacy between simplified Descemet stripping endothelial keratoplasty (DSEK) and penetrating keratoplasty (PKP) in the treatment of patients with bullous keratopathy (BK). A cohort of 65 patients (65 eyes) with BK recruited between December 2002 and June 2018 was divided into two groups according to the treatment they received: The simplified DSEK group (n=38) and the PKP group (n=27). The best-corrected visual acuity (BCVA) during the follow-up at 1, 3, 6 and 12 months and postoperative complications were all recorded. Furthermore, the graft survival rate after 1 year was recorded. The mean BCVA in the simplified DSEK group was significantly better than that in the PKP group after 1, 3, 6 and 12 months (P<0.05). Furthermore, the 1-year graft survival rate in the simplified DSEK group (91.2%) was significantly higher than that in the PKP group (70.4%; P=0.039). A total of 13 eyes (34.21%) in the simplified DSEK group and 11 eyes (40.74%) in the PKP group were diagnosed with glaucoma; there was no significant difference between the rate of glaucoma diagnosis between the two groups (P=0.591). Graft rejection was observed in 5 eyes (13.16%) of the simplified DSEK group and 8 eyes (29.63%) of the PKP group and the rate of graft rejection did not differ significantly between the groups (P=0.279). Graft infection occurred in 1 eye (2.63%) in the simplified DSEK group and 6 eyes (22.22%) in the PKP group. Simplified DSEK achieved better visual acuity and longer graft survival rates than PKP. The incidence of postoperative secondary glaucoma, graft rejection and graft infection after simplified DSEK was lower than that in the PKP group, but only the incidence of graft infection was significantly different.

Phototherapeutic keratectomy for anterior stromal fibrosis following DMEK

Purpose

Anterior stromal fibrosis is often seen in advanced cases of Fuchs endothelial dystrophy or secondary endothelial insufficiency. As Descemet membrane endothelial keratoplasty (DMEK) can completely eliminate the corneal edema and the guttae in these patients, anterior stromal fibrosis often remains leading to a reduction in visual function.

Observations

In such situations phototherapeutic keratectomy can be an effective tool to remove the opacifications in the anterior corneal stroma and improve the visual function as presented in two clinical cases.

Conclusion

DMEK can be the method of choice even in advanced cases of endothelial insufficiency with clinical significant fibrosis of the anterior corneal stroma.

Simultaneous Vitreoretinal Surgery and Penetrating Keratoplasty without a Keratoprosthesis or Endoscopy for Vitreoretinal Disease Associated with Corneal Opacity

We evaluated the visual outcome of combined penetrating keratoplasty (PKP) and 25G pars plana vitrectomy (PPV) performed without a temporary keratoprosthesis or endoscopy in a patient with vitreoretinal disease complicated by severe corneal opacity. The patient was a 68-year-old woman who had severe corneal opacity and silicone oil in her left eye after several previous intraocular surgeries for rhegmatogenous retinal detachment and proliferative vitreoretinopathy. We successfully performed a combined surgery of conventional PKP followed by 25G PPV without the use of a keratoprosthesis. At 6 months after surgery, visual acuity had not improved, and the density of corneal endothelial cells of the donor cornea had declined from 3,205 to 1,969 cells/mm². However, corneal transparency remained good, and additional surgery for vitreoretinal disease was not necessary. The combined surgical procedure designed to minimize the number of open-sky steps and to limit vitreoretinal complications thus proved to be safe and achieved stable corneal clarity in a patient with vitreoretinal disease and severe corneal opacity.

Temporary Filtering Bleb Failure Induced by Anterior Chamber Sulfur Hexafluoride Gas: A Complication after Descemet Membrane Endothelial Keratoplasty

Herein, we report two clinical cases with acute temporary filtering bleb obstruction by gas tamponade after Descemet membrane endothelial keratoplasty (DMEK) surgery and postoperative intraocular pressure (IOP) peaks. Both patients underwent uncomplicated DMEK surgery with 20% sulfur hexafluoride (SF₆) anterior chamber tamponade and had previous trabeculectomy for glaucoma. Prior to surgery, both patients showed patent bleb function with low to normal IOP without antiglaucomatous medication. After uneventful DMEK surgery, both patients showed postoperative IOP peaks of up to 50 mm Hg despite patent inferior iridotomy and no sign of a pupillary block. In both cases, SF₆ gas bubbles could be visualized obstructing the bleb. Both patients were treated with IOP-lowering agents topically as well as systemically. In addition, anterior chamber paracenteses were performed to reduce the SF₆ volume within the anterior chamber. Under this treatment, IOP normalized within the first 18 h after surgery. We hypothesize that the SF₆ gas tamponade from the anterior chamber migrates into the ostium and below the bleb, leading to an acute temporary insufficiency of bleb function and to a consecutive IOP peak after surgery. In contrast to a pupillary block, this mechanism cannot be antagonized by preoperative iridotomy and needs to be taken into account for every glaucoma patient with functional bleb undergoing DMEK surgery.

[Pathogenesis and diagnostic evaluation of Fuchs' endothelial corneal dystrophy]

BACKGROUND

Following new treatment options for Fuchs' endothelial corneal dystrophy, our understanding of optical and structural changes in the patient's cornea is also starting to improve.

OBJECTIVE

To provide an update on clinical evaluation of Fuchs' dystrophy.

MATERIAL AND METHODS

Standardized approaches to evaluate patients with Fuchs dystrophy in routine practice and research are discussed, accounting for the progressive and partially irreversible structural changes in all corneal layers.

RESULTS

Early structural changes in the cornea can be detected before clinical edema becomes visible on slit-lamp exam. Optical limitations resulting from these structural changes can be quantified not only with high-contrast acuity but also with glare or contrast sensitivity tests. Characteristic vision-related limitations of patients with Fuchs dystrophy can, e.g., be assessed with V-FUCHS, a Fuchs dystrophy-specific "Visual Function and Corneal Health Status" instrument for patient-reported outcomes.

CONCLUSION

Clinical grading of Fuchs dystrophy in an edematous and a non-edematous stage is outdated. Better therapy options and our improved understanding of progressive changes in the entire cornea require a standardized assessment of optical and structural changes and patient-reported limitations.

[Boston type I keratoprosthesis implantation technique : Video article]

BACKGROUND

Keratoprosthetics refer to the replacement of human corneal tissue with an artificially produced exchange product. The most widely implanted keratoprosthesis worldwide is the Boston Type I Keratoprosthesis (BI-KPro, Massachusetts Eye and Ear Infirmary, Boston, MA, USA).

METHODS

This video article demonstrates the surgical technique of BI-KPro implantation as routinely performed at this institution. In addition, an overview of the surgical indications, patient consent, anesthesia and positioning, postoperative treatment and complications as well as the evidence of the technique is provided in the article based on experience with 31 BI-KPro implantations.

RESULTS

The indications for BI-KPro primarily include patients in a high-risk keratoplasty setting particularly after repeatedly failed keratoplasty. A thorough patient examination and assessment of the indications as well as detailed disclosure of information to the patient about the individual prognosis, the risk profile, the postoperative therapy and follow-up enable a positive postoperative result.

CONCLUSION

The BI-KPro provides an established and relatively standardized option for surgical treatment of eyes in a high-risk keratoplasty setting. Patients should be preoperatively informed with respect to the individual prognosis, complication profile and life-long follow-up.

Evaluation of interface reflectivity and corneal aberrations following Descemet's stripping automated endothelial keratoplasty

PURPOSE:

This study aims to evaluate visual outcome after Descemet's membrane stripping automated endothelial keratoplasty (DSAEK) and relate to interface and corneal higher-order aberrations (HOAs).

MATERIALS AND METHODS:

We enrolled 16 eyes of 16 patients (eight males and eight females) in this interventional case series and followed DSAEK operation for about two to 20 months. OCULUS Pentacam, as well as other ophthalmic evaluations in follow-up visits, examined interface reflectivity and HOAs. Statistical relations were analyzed.

RESULTS:

There was statistically significant correlation between interface reflectivity and best corrected visual acuity (BCVA) (r = 0.56, P = 0.021). Pachymetry (central corneal thickness) and BCVA had a moderate correlation (r = 0.6, P = 0.013). There was no statistically significant correlation between pachymetry and follow-up time (r = −0.36, P = 0.16). Negative correlation between follow-up and interface reflectivity was also not statistically significant (r = −0.24, P = 0.35). Coma had a significant correlation with BCVA in cornea and cornea front maps (r = 0.74, P = 0.009 and r = 0.71, P = 0.013, respectively).

CONCLUSION:

Significant correlation between interface reflectivity and BSCVA was found, and anterior corneal HOAs are significantly higher than posterior HOAs.

3D in vitro model for human corneal endothelial cell maturation

Corneal endothelium is a cellular monolayer positioned on the Descemet's membrane at the anterior cornea, and it plays a critical role in maintaining corneal clarity. Our present study examines the feasibility of utilizing our 3-dimensional (3D) corneal stromal construct, which consists of human corneal fibroblasts (HCF) and their self-assembled matrix, to observe the development and maturation of human corneal endothelial cells (HCEndoCs) in a co-culture model. Three-dimensional HCF constructs were created by growing the HCFs on Transwell membranes in Eagles' minimum essential medium (EMEM) + 10% FBS + 0.5 mM Vitamin C (VitC) for about 4 weeks. HCEndoCs, either primary (pHCEndoC) or cell line (HCEndoCL), were either seeded in chamber slides, directly on the Transwell membranes, or on the 3D HCF constructs and cultivated for 5 days or 2 weeks. The HCEndoCs that were seeded directly on the Transwell membranes were exposed indirectly to HCF by culturing the HCF on the plate beneath the membrane. Cultures were examined for morphology and ultrastructure using light and transmission electron microscopy (TEM). In addition, indirect-immunofluorescence microscopy (IF) was used to examine tight junction formation (ZO-1), maturation (ALDH1A1), basement membrane formation (Laminin), cell proliferation (Ki67), cell death (caspase-3), and fibrotic response (CTGF). As expected, both pHCEndoCs and HCEndoCLs formed monolayers on the constructs; however, the morphology of the HCEndoCLs appeared to be similar to that seen in vivo, uniform and closely packed, whereas the pHCEndoCs remained elongated. The IF data showed that laminin localization was present in the HCEndoCs' cytoplasm as cell-cell contact increased, and when they were grown in the 3D co-culture, the beginnings of what appears to be a continuous DM-like structure was observed. In addition, in co-cultures, ALDH1A1-positive HCEndoCs were present, ZO-1 expression localized within the tight junctions, minimal numbers of HCEndoCs were Ki67-or Caspase-3-positive, and CTGF was positive in both the HCEndoCs cytoplasm and the matrix of the co-culture. Also, laminin localization was stimulated in HCEndoCs upon indirect stimuli secreted by HCF. The present data suggests our 3D co-culture model is useful for studying corneal endothelium maturation in vitro since the co-culture promotes new DM-like formation, HCEndoCs develop in vivo-like characteristics, and the fibrotic response is activated. Our current findings are applicable to understanding the implications of corneal endothelial injection therapy, such as if the abnormal DM has to be removed from the patient, the newly injected endothelial cells will seed onto the wound area and deposit a new DM-like membrane. However, caution should be observed and as much of the normal DM should be left intact since removal of the DM can cause a posterior stromal fibrotic response.

Machine learning for segmenting cells in corneal endothelium images

Images of the endothelial cell layer of the cornea can be used to evaluate corneal health. Quantitative biomarkers extracted from these images such as cell density, coefficient of variation of cell area, and cell hexagonality are commonly used to evaluate the status of the endothelium. Currently, fully-automated endothelial image analysis systems in use often give inaccurate results, while semi-automated methods, requiring trained image analysis readers to identify cells manually, are both challenging and time-consuming. We are investigating two deep learning methods to automatically segment cells in such images. We compare the performance of two deep neural networks, namely U-Net and SegNet. To train and test the classifiers, a dataset of 130 images was collected, with expert reader annotated cell borders in each image. We applied standard training and testing techniques to evaluate pixel-wise segmentation performance, and report corresponding metrics such as the Dice and Jaccard coefficients. Visual evaluation of results showed that most pixel-wise errors in the U-Net were rather non-consequential. Results from the U-Net approach are being applied to create endothelial cell segmentations and quantify important morphological measurements for evaluating cornea health.

Factors Associated With Graft Rejection in the Cornea Preservation Time Study

PURPOSE

To identify factors related to graft rejection following Descemet stripping automated endothelial keratoplasty (DSAEK) in the Cornea Preservation Time Study (CPTS).

DESIGN

Cohort study within a multicenter randomized clinical trial.

METHODS

A total of 1330 eyes of 1090 subjects undergoing DSAEK were randomized to receive a donor cornea with preservation time (PT) of 0-7 days (n = 675) or 8-14 days (n = 655) and followed for 3 years. Central endothelial cell density (ECD) was determined by a central image analysis reading center. Multivariable Cox models adjusted for PT, recipient diagnosis, and surgeon effect were used to identify factors associated with rejection.

RESULTS

Cumulative probability of definite graft rejection was 3.6% (99% confidence interval 2.5%-5.3%). Younger recipient age was associated with graft rejection (P < .001; hazard ratio: 0.53 [0.33, 0.83] per decade). PT, donor-recipient sex mismatch, recipient diagnosis, recipient race, graft size, discontinuation of topical corticosteroids and immune-modulators, prior immunizations within 3 months, and prior glaucoma surgery were not associated with rejection (P > .01). Among clear grafts with an ECD measurement at baseline and 3 years (n = 913), endothelial cell loss (ECL) was greater in eyes that experienced a rejection episode (n = 27) than in those that did not (n = 886) (48% vs 38%, P = .03). Twelve of 44 eyes (27%) with definite graft rejection subsequently failed, comprising 15% of the 79 failures in the CPTS.

CONCLUSIONS

Graft rejection is uncommon after DSAEK and more likely with younger age, in a study cohort mostly > 50 years old. Rejection increases ECL, but it is not a leading cause of DSAEK failure.

Lamellar keratoplasty techniques

Lamellar keratoplasty (LK) has revolutionized corneal graft surgery in several ways. Deep anterior LK (DALK) has eliminated risk of failure due to endothelial rejection. Endothelial keratoplasty (EK) has almost eliminated induced astigmatism and the “weak” graft–host junction as seen with penetrating keratoplasty (PK) and also reduced the risk of endothelial rejection. LK provided new insights into posterior corneal anatomy that led to better understanding and performance of DALK and to the development of another EK procedure, namely pre-Descemet's EK (PDEK). Surgical procedures for LK were further refined based on the improved understanding and are able to deliver better surgical outcomes in terms of structural integrity and long-term patient satisfaction, reducing the need of further surgeries and minimizing patient discomfort. In most specialist centers, anterior lamellar techniques like DALK and EK techniques like Descemet's stripping EK (DSEK) and Descemet's membrane EK (DMEK) have replaced the full-thickness PK where possible. The introduction of microkeratome, femtosecond laser, and PDEK clamp have made LK techniques easier and more predictable and have led to the innovation of another LK procedure, namely Bowman membrane transplant (BMT). In this article, we discuss the evolution of different surgical techniques, their principles, main outcomes, and limitations. To date, experience with BMT is limited, but DALK has become the gold standard for anterior LK. The EK procedures too have undergone a rapid transition from DSEK to DMEK and PDEK emerging as a viable option. Ultrathin-DSEK may still have a role in modern EK.

From DMEK to Corneal Endothelial Cell Therapy: Technical and Biological Aspects

The main treatment available for restoration of the corneal endothelium is keratoplasty and DMEK provides faster visual recovery and better postoperative visual acuity when compared to DSAEK. However, the technical challenges related to this technique and the steep technical learning curve seem to prevent the overcoming of DSAEK in favor of DMEK. Furthermore, the outcome of lamellar keratoplasty techniques is influenced by problems related to corneal grafting tissue availability, management, and quality. On the other hand, improvements in the field of cell engineering have opened the way for the use of stem cells-derived corneal endothelial cells with regenerative intent. In this overview, latest findings in endothelial cell engineering are reported, and perspectives of clinical application of mesenchymal stem cells for corneal endothelial replacement and regeneration are evaluated.

Descemet's membrane endothelial keratoplasty (DMEK) versus Descemet's stripping automated endothelial keratoplasty (DSAEK) for corneal endothelial failure

BACKGROUND

Corneal endothelial transplantation has become the gold standard for the treatment of corneal endothelial dysfunctions, replacing full thickness transplantation, known as penetrating keratoplasty. Corneal endothelial transplantation has been described using two different techniques: Descemet's membrane endothelial keratoplasty (DMEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK). Both are still performed worldwide.

OBJECTIVES

To compare the effectiveness and safety of Descemet's membrane endothelial keratoplasty (DMEK) versus Descemet's stripping automated endothelial keratoplasty (DSAEK) for the treatment of corneal endothelial failure in people with Fuch's endothelial dystropy (FED) and pseudophakic bullous keratopathy (PBK).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 7); MEDLINE Ovid; Embase Ovid; LILACS BIREME; the ISRCTN registry; ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). The date of the search was 11 August 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised paired, contralateral-eye studies in any setting where DMEK was compared with DSAEK to treat people with corneal endothelial failure.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, assessed trial quality and extracted data using the standard methodological procedures expected by Cochrane. Our primary outcome was best corrected visual acuity (BCVA) measured in logarithm of the Minimum Angle of Resolution (logMAR). Secondary outcomes were endothelial cell count, graft rejection, primary graft failure and graft dislocation. We graded the risk of bias of non-randomised studies (NRSs) using ROBINS-I.

MAIN RESULTS

We did not identify any RCTs but found four non-randomised studies (NRSs) including 72 participants (144 eyes), who had received DSAEK in the first eye followed by DMEK in the fellow eye. All the studies included adult participants where there was evidence of FED and endothelial failure requiring a corneal transplant for the treatment of visual impairment. We did not find any studies that included PBK. The trials were published between 2011 and 2015, and we assessed them as high risk of bias due to potential unknown confounding factors since DSAEK preceded DMEK in all participants. Two studies reported results at 12 months, one at 6 months, and one between 6 and 24 months. At one year, using DMEK in cases of endothelial failure may result in better BCVA compared with DSAEK (mean difference (MD) -0.14, 95% confidence interval (CI) -0.18 to -0.10 logMAR, 4 studies, 140 eyes, low-certainty evidence). None of the participants had severe visual loss (BCVA of 1.0 logMAR or more; very low-certainty evidence). Regarding endothelial cell count data (4 studies, 134 eyes) it is hard to draw any conclusions since two studies suggested no difference and the other two reported that DMEK provides a higher cell density at one year (very low-certainty evidence). No primary graft failure and only one graft rejection were recorded over four studies (144 eyes) (very low-certainty evidence). The most common complications reported were graft dislocations, which were recorded in one or two out of 100 participants with DSAEK but were more common using DMEK, although this difference could not be precisely estimated (risk ratio (RR) 5.40, 95% CI 1.51 to 19.3; 4 studies, 144 eyes, very low-certainty evidence).

AUTHORS' CONCLUSIONS

This review included studies conducted on people with corneal endothelium failure due to FED for whom both DMEK and DSAEK can be considered, and found low-certainty evidence that DMEK provides some advantage in terms of final BCVA, at the cost of more graft dislocations needing 're-bubbling' (very low-certainty of evidence).

Impact of corneal donor lens status on two-year course and outcome of Descemet membrane endothelial keratoplasty (DMEK)

PURPOSE

Our purpose was to investigate the impact of lens status of corneal donors on the two-year course and clinical outcome of Descemet membrane endothelial keratoplasty (DMEK).

METHODS

In 181 DMEK surgeries, 136 phakic and 45 pseudophakic donor corneas were grafted. In this retrospective audit we compared the lens status of corneal donors regarding the outcome measures best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) at 1, 3, 6, 12, and 24 months, as well as intra- and postoperative complication rates and graft detachment rates requiring re-bubbling.

RESULTS

Comparing the use of phakic and pseudophakic donor tissue in DMEK surgery, BSCVA results revealed no significant differences during the two-year course (p ≥ 0.087). CCT showed significantly lower values at 1 month (553.8 ± 56 vs. 625.2 ± 119 μm; p < 0.001) and 6 months follow-up (530.6 ± 49.9 vs. 557.3 ± 47 μm; p = 0.026) for phakic donor tissue recipients, but were comparable later (p ≥ 0.173). ECD values were statistically higher 6 (1915 ± 390 vs. 1565 ± 420 cells/mm²; p < 0.001) and 24 months postoperatively (1772 ± 384 vs. 1375 ± 377 cells/mm²; p = 0.030) in phakic donor tissue recipients. Mixed regression analyses demonstrated a significant association between ECD results and donor lens status (p = 0.029) and donor ECD (p = 0.028), but donor age did not show significant influence (p = 0.241).

CONCLUSION

ECD is higher in phakic corneal donors and appears to remain at a higher level during the course resulting in initially faster reduction of corneal edema compared to pseudophakic DMEK grafts. Nevertheless, pseudophakic transplants with high ECD seem to produce comparable functional results in recipients after a two year course.

Endothelial keratoplasty for posterior polymorphous corneal dystrophy in a 4-month-old infant

Purpose

To report a case of endothelial keratoplasties (EKs) performed in a 4 month old with a posterior polymorphous corneal dystrophy.

Observations

A 4 month old infant underwent Descemet membrane endothelial keratoplasty (DMEK) for posterior polymorphous corneal dystrophy. The graft was found to be dislocated on day 5 post-operatively and an attempt to unfold the DMEK scroll and re-bubble was not successful. The patient was then treated successfully with bilateral Descemet stripping automated endothelial keratoplasty (DSAEK). At 3 years of follow-up, her visual acuity was 20/70 in the right and 20/60 in the left eye with good endothelial cell counts.

Conclusions and importance

and Importance: This study reports the youngest case of EKs performed at the age of 4 months in an infant. This is also the first reported case of attempted DMEK highlighting its challenges in infants. DSAEK remains a good treatment option for endothelial dysfunction secondary to posterior polymorphous corneal dystrophy in infants even after failed DMEK.

Clinical results of non-Descemet stripping endothelial keratoplasty

AIM

To investigate the impact of non-Descemet stripping endothelial keratoplasty (non-DSEK) on graft rejection rate, and its overall procedural effectiveness in patients.

METHODS

Non-DSEK was performed on 65 eyes of 64 patients, and the procedural outcomes, including rejection episodes, failure and dislocation of the grafts, best corrected visual acuity (BCVA), endothelial cell density (ECD), and other complications, were analyzed retrospectively.

RESULTS

Of the 65 eyes, 63 recovered from bullous keratopathy with a clear cornea. The mean follow-up time was 26.4mo (range, 6-84mo). The mean BCVA improved from 1.70 logMAR preoperatively to 0.54 logMAR at 3mo, 0.46 logMAR at 6mo, and 0.37 logMAR at 1y after surgery. The postoperative donor ECD of the 25 patients who successfully underwent specular microscopic examination was 1918±534 cells/mm² (range, 637 to 3056 cells/mm²), and the mean endothelial cell loss was 41.9% at 24mo postoperatively. One eye developed secondary glaucoma and required regrafting via penetrating keratoplasty (PKP). Another eye had postoperative graft failure due to rejection at 26mo. Postoperative graft dislocation occurred in eight eyes. All of the eight dislocated grafts were reattached using air reinjection.

CONCLUSION

Immunological graft rejection of the donor graft rarely occurs in non-DSEK. Therefore, non-DSEK is a safe, concise, and effective alternative to restore corneal decompensation when the Descemet membrane is disease-free.

[Update: Deep anterior lamellar keratoplasty (DALK) for keratoconus. When, how and why]

BACKGROUND

The treatment of keratoconus has been significantly expanded in recent years. In addition to the previous options for correction by fitting hard contact lenses and penetrating keratoplasty (PK), corneal cross-linking and lamellar transplantation techniques have been added.

OBJECTIVE

The aim of this review article is to highlight currently available options for minimization of complications and standardization of deep anterior lamellar keratoplasty (DALK) for keratoconus.

MATERIAL AND METHODS

This article summarizes our own data and gives a review of the literature in PubMed.

RESULTS

Performing DALK can provide keratoconus patients with corneal grafts with considerably longer graft survival and a reduced risk of complications.

CONCLUSION

The DALK procedure provides numerous advantages over PK, especially the reduced intraoperative opening of the eye, which thus reduces the risk of serious intraoperative complications. A further benefit is the complete absence of postoperative endothelial immune reactions as the recipient's endothelium remains untouched. The absence of endothelial immune reactions is especially advantageous for young patients with keratoconus and patients with an increased risk of graft rejection, e.g. in atopic dermatitis; however, there are also typical complications of DALK that do not occur during PK. The outlined strategies for standardization of DALK and avoidance of intraoperative and postoperative complications should make DALK safer and more reproducible and lead to possible establishment as a standard procedure in keratokonus.

[Influence of 20 % sulfur hexafluoride (SF6) on human corneal endothelial cells : An in vitro study]

BACKGROUND

In posterior lamellar keratoplasties, such as Descemet membrane endothelial keratoplasty (DMEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK) an air bubble is left inside the anterior chamber to promote graft attachment during the early postoperative period. In the case of insufficient graft adhesion a renewed intracameral air injection is often necessary. The use of sulfur hexafluoride diluted with air (SF6 20 %) as an alternative to pure air may further enhance graft attachment and reduce the rebubbling rate. The effect of SF6 20 % on corneal endothelium is currently unclear and was therefore examined in vitro.

MATERIAL AND METHODS

For this study 12 human corneoscleral discs were mounted in artificial anterior chambers, the systems were continuously filled with culture medium and the anterior chambers with air (n = 5) or SF6 20 % (n = 7) as tamponade. After 6 days of storage in the incubator endothelial cell density, toxicity on endothelial cells and corneal thickness were evaluated.

RESULTS

There were no significant differences in endothelial cell loss (p = 1.000), endothelial cell count (p = 0.648), toxicity on endothelial cells (p = 0.048) and central corneal thickness (p = 0.905) between the two groups after 1 week. The level of significance was defined as p ≤ 0.05 and adjusted to p ≤ 0.0056 according to the Bonferroni correction for multiple testing.

CONCLUSION

The use of SF6 20 % as tamponade in the anterior chamber for posterior lamellar keratoplasty can be proposed as a safe alternative to pure air filling related to endothelial cell loss. Increased toxic effects on the corneal endothelium by SF6 20 % were not detected in this study; however, further prospective clinical trials are needed to examine the long-term effects in humans.

[Complications of deep anterior lamellar keratoplasty. Avoid, recognize and treat]

Deep anterior lamellar keratoplasty (DALK) offers tremendous advantages over penetrating keratoplasty (PK). Intraoperative safety is increased due to reduced opening of the eye interoperatively and the fact that no endothelial graft rejection can take place as the patient's own corneal endothelium is retained. Despite these advantages the number of DALK procedures performed each year in Germany remains constant at a low level. One reason could be that the DALK technique offers some complexity and at the same time intraoperative conversion to PK has to be performed in some cases due to rupture of Descemet's membrane. Moreover, interface-related and DALK-specific complications exist which can contribute to an unfavorable visual outcome. Most of these complications, such as incomplete attachment of Descemet's membrane or opacification within the interface between Descemet's membrane and the posterior corneal stoma can be resolved by adequate measures making PK for revision barely necessary. As visual acuity does not differ between PK and DALK, the benefits of DALK - lack of endothelial immune reaction and increased ocular stability during surgery - outweigh the risk of additional complications and DALK should therefore be performed whenever appropriate.

Optimizing rejection readouts in a corneal allograft transplantation model

PURPOSE

To evaluate the feasibility of anterior segment spectral domain optic coherence tomography (ASOCT) as rejection readout in a keratoplasty mouse model and to compare ASOCT against the current standard (i.e., a clinical score system). Furthermore, to compare both approaches with respect to intra- and inter-individual observer variability and to calculate a critical point that distinguishes between rejection and non-rejection in ASOCT analysis.

METHODS

Allogeneic penetrating keratoplasties (PKs) were performed using C3H/He donor mice and BALB/c recipient mice; syngeneic transplantations served as controls using BALB/c donors and recipients. Corneal graft rejection was determined with a clinical score. ASOCT was used to determine the central thickness of the corneal grafts in the same animals. The rejection status was corroborated with histopathological examination.

RESULTS

The median survival time (MST) of the corneal allografts in the wild-type BALB/c mice was 12 days. Allogeneic transplantation led to a 100% rejection rate, whereas signs of rejection after syngeneic transplantation appeared in up to 20% of the mice. Central corneal thickness (CCT) determination via customized software revealed a direct correlation with the clinical score. Receiver operating curve (ROC) analysis confirmed CCT as a valid surrogate for rejection. Calculation of the area under the curve (AUC) revealed a value of 0.88 with an optimal cut-off at 267 pixels.

CONCLUSIONS

An increase in the CCT during acute allogeneic corneal graft rejection significantly correlated with the clinical surrogate parameter "corneal opacity." ASOCT not only generates source data, but also analysis of the ASOCT data shows lower readout variability and fewer interpreter variations than the clinical score commonly used to define the time point of graft rejection in mice.

Effects of corneal stromal cell- and bone marrow-derived endothelial progenitor cell-conditioned media on the proliferation of corneal endothelial cells

AIM

To explore the effects of conditioned media on the proliferation of corneal endothelial cells (CECs) and to compare the efficiency of different conditioned media (CM).

METHODS

Rat CECs, corneal stromal cells (CSCs), bone marrow-derived endothelial progenitor cells (BEPCs), and bone marrow-derived mesenchymal stem cells (BMSCs) were isolated and cultured in vitro. CM was collected from CSCs, BEPCs, and BMSCs. CECs were cultivated in different culture media. Cell morphology was recorded, and gene and protein expression were analyzed.

RESULTS

After grown in CM for 5d, CECs in each experimental group remained polygonal, in a cobblestone-like monolayer arrangement. Immunocytofluorescence revealed positive expression of Na(+)/K(+)-ATP, aquaporin 1 (AQP1), and zonula occludens 1 (ZO-1). Based on quantitative polymerase chain reaction (qPCR) analysis, Na(+)/K(+)-ATP expression in CSC-CM was notably upregulated by 1.3-fold (±0.036) (P<0.05, n=3). The expression levels of ZO-1, neuron specific enolase (NSE), Vimentin, paired homebox 6 (PAX6), and procollagen type VIII (COL8A1) were notably upregulated in each experimental group. Each CM had a positive effect on CEC proliferation, and CSC-CM had the strongest effect on proliferation.

CONCLUSION

CSC-CM, BEPC-CM, and BMSC-CM not only stimulated the proliferation of CECs, but also maintained the characteristic differentiated phenotypes necessary for endothelial functions. CSC-CM had the most notable effect on CEC proliferation.

Fuchs endothelial corneal dystrophy: current perspectives

Fuchs endothelial corneal dystrophy (FECD) is the most common corneal dystrophy and frequently results in vision loss. Hallmarks of the disease include loss of corneal endothelial cells and formation of excrescences of Descemet's membrane. Later stages involve all layers of the cornea. Impairment of endothelial barrier and pump function and cell death from oxidative and unfolded protein stress contribute to disease progression. The genetic basis of FECD includes numerous genes and chromosomal loci, although alterations in the transcription factor 4 gene are associated with the majority of cases. Definitive treatment of FECD is corneal transplantation. In this paper, we highlight advances that have been made in understanding FECD's clinical features, pathophysiology, and genetics. We also discuss recent advances in endothelial keratoplasty and potential future treatments.

[Treatment of corneal endothelial disorders by DMEK and UT-DSAEK. Indications, complications, results and follow-up]

Various techniques for posterior lamellar keratoplasty have been established for the clinical routine and continuously improved during the last 15 years so that an extremely rapid recovery of vision is possible due to very thin transplants. Descemet membrane endothelial keratoplasty (DMEK) is the method of choice for simple corneal endothelial diseases and has already been applied in complex conditions of the anterior segment. The learning curve for DMEK is comparatively long and the risk of complications in complex anterior segment pathologies is higher than in Descemet's stripping automated endothelial keratoplasty (DSAEK); however, DMEK results in better visual outcome and less graft rejections than DSAEK. The latest evolution in posterior lamellar transplant surgery is ultrathin DSAEK (UT-DSAEK), where the grafted lamella is much thinner than in conventional DSAEK. Currently available data suggest that the resulting visual acuity after UT-DSAEK is close to the visual acuity seen after DMEK; however, studies comparing the results after DMEK and UT-DSAEK are so far lacking. Whether the transplantation of these very thin DSAEK grafts also results in endothelial cell densities and graft rejection rates comparable to DMEK has to be proven.

[Complications of Descemet Stripping Automated Endothelial Keratoplasty (DSAEK)]

BACKGROUND

Lamellar keratoplasties, e.g. Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) are considered the procedures of choice for corneal endothelial diseases. In comparison to penetrating keratoplasty (PK) they are associated with faster visual rehabilitation, a lower risk of complications and a decreased necessity for follow-up visits, which reduces the burden on quality of life in elderly patients. In order to advise patients regarding the indications for surgery and to facilitate the follow-up management, it is important to know the most important complications associated with these keratoplasty techniques.

RESULTS AND DISCUSSION

The most important preoperative complication is a delayed indication for the operation. In contrast to PK, DSAEK and DMEK surgery should be provided at an earlier stage of disease as chronic edema alters the stroma and reduces the speed of visual recovery. The most important complications during or early after surgery are detached lamellae, pupillary blocks with increased pressure or air bubbles in the vitreous cavity in patients with previous vitrectomy. The main long-term complications include chronic increased intraocular pressure and immune-mediated graft rejections in DSAEK patients after reducing or stopping topical corticosteroid therapy. This article describes the potential complications of endothelial keratoplasty and provides a detailed explanation of strategies to avoid these complications.

[Current treatment options with artificial corneas: Boston Kpro, Osteo-odontokeratoprosthesis, Miro Cornea® and KeraKlear®]

BACKGROUND

Although corneal transplant surgery in avascular normal risk eyes is becoming even more minimally invasive and successful, treatment options for difficult to treat patients with high risk eyes are still limited. In these cases HLA typed allogeneic transplants and artificial corneas (keratoprostheses) can be used.

METHODS

This article combines a review of the literature in PubMed and own clinical experiences on the use of artificial corneas in high risk eyes. Osteo-odontokeratoprosthesis (OOKP), Boston Kpro, Miro Cornea® and KeraKlear® corneas were used as clinical keratoprostheses.

RESULTS

Worldwide, the most experience exists for the use of Boston Kpro and OOKP in high risk eyes. Miro Cornea® and KeraKlear® are new procedures where only preliminary results are available and further evaluation is necessary. The longest experience and best anatomical long-term results have been achieved with OOKPs. Comparable cohorts are available for the Boston Kpro. The function of all keratoprostheses is threatened by secondary glaucoma. Implantation of the KeraKlear® prosthesis remains difficult. The Miro Cornea® shows an initially stable integration behavior.

CONCLUSION

Keratoprostheses, such as the Boston Kpro and OOKP are valid treatment options for eyes which are not open to therapy with allogeneic corneal transplantation. Modern implants such as KeraKlear® prosthesis and Miro Cornea® need further prospective clinical evaluation.

[Perforating keratoplasty versus Descemet stripping automated endothelial keratoplasty in the partner eye: Functional results and patient satisfaction]

BACKGROUND

This study compared the postoperative results and patient satisfaction between penetrating keratoplasty (PK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in patients who underwent PK in one eye and DSAEK in the other eye.

METHODS

A total of 15 patients were identified from the corneal database register and the medical charts were analyzed for best corrected visual acuity (BCVA), keratometric astigmatism, endothelial cell density and postoperative complications. Patient satisfaction was evaluated by a standardized interview.

RESULTS

Median follow-up time for PK was 55 months and 18 months for DSAEK (p < 0.01). Median BCVA in PK was 0.8 and 0.5 in DSAEK (p = 0.01) at the end of follow-up. Median keratometric astigmatism was 3.1 diopters after PK and 1.9 diopters after DSAEK (p = 0.2). Median endothelial cell density was 831 cells/mm(2) after PK and 860 cells/mm(2) after DSAEK (p = 0.63). For the interventions 57 % of the patients preferred PK, 36 % preferred DSAEK and 7 % were undecided. Patients assigned the better performing eye to the PK side in 64 % and in 29 % to the DSAEK side and 7 % perceived equal visual performance in both eyes.

CONCLUSION

The results leave doubt about the superiority of DSAEK compared to PK; however, exceptionally good refractive results of the 15 PK eyes analyzed and significantly longer follow-up times after PK could be the reason for the unexpectedly high patient preference for PK.

[Decellularized collagen matrix from tilapia fish scales for corneal reconstruction (BioCornea)]

BACKGROUND

The worldwide need for donor corneal tissue clearly exceeds the availability of transplantable human tissue; therefore, recent efforts aim to identify and characterize alternative tissues, such as decellularized collagen scaffolds.

OBJECTIVES

The transparent fish scales of tilapia (Oreochromis mossambicus) were analyzed as a potential alternative for corneal reconstruction ("BioCornea").

MATERIAL AND METHODS

The article gives a review of the literature and own preliminary results. After decellularization the tissue characteristics of the fish scales, the repopulation with corneal epithelium and stromal cells, immunogenicity, the feasibility of corneal transplantation and the angiogenic properties were analyzed in vitro and in various animal models.

RESULTS

The fish scales mainly consist of collagen type I and show an architecture that is similar to the human cornea. Corneal epithelium and stromal cells are able to grow over and into the scaffold. It is possible to transplant fish scales in various animal models without severe inflammatory responses. Furthermore, in mice, less blood and lymphatic vessels grow into the xenograft when compared to conventional allogenic transplants.

CONCLUSION

Preliminary results with decellularized tilapia fish scales as an alternative for corneal reconstruction ("BioCornea") are promising.

[Standardized Descemet membrane endothelial keratoplasty (DMEK): technique and latest results]

BACKGROUND

The procedure of posterior lamellar keratoplasty has now become established as first choice therapy for the treatment of corneal endothelial diseases, with Descemet membrane endothelial keratoplasty (DMEK) as the most recent refinement of endothelial keratoplasty techniques. In this study the outcome of 400 consecutive cases after standardized no-touch DMEK was evaluated.

METHODS

This was a non-randomized retrospective clinical study of 400 consecutive eyes in 321 patients who underwent standard DMEK. Outcome measures included best corrected visual acuity (BCVA) preoperatively and postoperatively at 1, 3 and 6 months, endothelial cell density (ECD), pachymetry and complications within the first 6 months. In addition two subgroups were analyzed (subgroup I cases 1-200 and subgroup II cases 201-400).

RESULTS

At 6 months postoperatively 80 % of all eyes had a BCVA of ≥ 20/25 (≥ 0.8), 44 % of ≥ 20/20 (≥ 1.0) and 14 % of ≥ 20/18 (≥ 1.2). There were no significant differences between the two subgroups. The mean ECD preoperatively was 2,542 (± 217) cells/mm(2) and 6 months postoperatively 1,622 (± 500) cells/mm(2). The mean ECD decrease was 36 % 6 months after DMEK. No difference between the subgroups was noted. In 5 % a re-operation was needed of which 75 % were performed in subgroup I.

CONCLUSION

With the standardized no-touch DMEK technique a rapid and nearly complete visual rehabilitation as well as ECD values similar to earlier endothelial keratoplasty techniques can be achieved. Therefore DMEK may become the preferred treatment for corneal endothelial disorders.