BackgroundCorneal cross-linking is widely used to treat keratoconus. However, to date, only limited data from randomized trials support its efficacy.MethodsThe efficacy and safety of corneal cross-linking for halting progression of keratoconus were investigated in a prospective, randomized, blinded, placebo controlled, multicentre trial. Twenty-nine keratoconus patients were randomized in three trial centres. The mean age at inclusion was 28 years. Longitudinal changes in corneal refraction were assessed by linear regression. The best corrected visual acuity, surface defects and corneal inflammation were also assessed. These data were analysed with a multifactorial linear regression model.ResultsA total of 15 eyes were randomized to the treatment and 14 to the control group. Follow-up averaged 1098 days. Corneal refractive power decreased on average (+/−standard deviation) by 0.35 +/− 0.58 dioptres/year in the treatment group. The controls showed an increase of 0.11 +/− 0.61 dioptres/year. This difference was statistically significant (p = 0.02).ConclusionsOur data suggest that corneal cross-linking is an effective treatment for some patients to halt the progression of keratoconus. However, some of the treated patients still progressed, whereas some untreated controls improved. Therefore, further investigations are necessary to decide which patients require treatment and which do not.Trial registrationNCT00626717, Date of registration: February 20, 2008.

BackgroundRecently, novel techniques introduced to the field of corneal surgery, e.g. Descemet membrane endothelial keratoplasty (DMEK) and corneal crosslinking, extended the therapeutic options. Additionally contact lens fitting has developed new alternatives. We herein investigated, whether these techniques have affected volume and spectrum of indications of keratoplasties in both a center more specialized in treating Fuchs’ dystrophy (center 1) and a second center that is more specialized in treating keratoconus (center 2).MethodsWe retrospectively reviewed the waiting lists for indication, transplantation technique and the patients’ travel distances to the hospital at both centers.ResultsWe reviewed a total of 3778 procedures. Fuchs’ dystrophy increased at center 1 from 17% (42) to 44% (150) and from 13% (27) to 23% (62) at center 2. In center 1, DMEK increased from zero percent in 2010 to 51% in 2013. In center 2, DMEK was not performed until 2013. The percentage of patients with keratoconus slightly decreased from 15% (36) in 2009 vs. 12% (40) in 2013 in center 1. The respective percentages in center 2 were 28% (57) and 19% (51). In both centers, the patients’ travel distances increased.ConclusionsThe results from center 1 suggest that DMEK might increase the total number of keratoplasties. The increase in travel distance suggests that this cannot be fully attributed to recruiting the less advanced patients from the hospital proximity. The increase is rather due to more referrals from other regions. The decrease of keratoconus patients in both centers is surprising and may be attributed to optimized contact lens fitting or even to the effect corneal crosslinking procedure.

AimThe objective of the study was to evaluate the long-term results of allogenic penetrating limbo-keratoplasy. This method allows simultaneous transplantation of a corneal graft and limbal stem cells of the donor by means of eccentric trephination of the donor button.MethodThe data of 192 consecutive cases of allogenic penetrating limbo-keratoplasty from 1995 to 2015 were reviewed. These had been performed exclusively in eyes with complete failure of the limbal stem cells, in combination with deep corneal scarring. Indications were predominantly eye burns, inflammatory conditions, and congenital aniridia. Graft survival and rejection rates were assessed using Kaplan-Meier analysis.ResultsFollow-up averaged 2.1±2.2 years. Median graft survival was 3.4 years in eye burns, 3.9 years in inflammatory disease, and 3.2 years in congenital aniridia. Median survival was 3.9 years in the heterogenous group of other indications.ConclusionAllogenic limbo-keratoplasty is a suitable option used to treat patients with bilateral complete failure of the limbal stem cells and deep opacification of the central cornea. The main reasons for graft failure are the loss of graft-limbal stem cell functioning and endothelial graft rejection.

Purpose We retrospectively studied the efficacy and safety of different surgical approaches to treating pediatric limbal dermoids with regard to intra and postoperative complications. Methods The data of 12 consecutive patients (14 eyes), who underwent monocentric surgery of a limbal demoid in the past 9 years, were retrospectively analyzed for intra and postoperative complications. Group one consists of eleven eyes: seven eyes with a bare-sclera deep lamellar excision of the dermoid and four eyes with an additional amniotic membrane transplantation subsequent to excision. Group two consists of three eyes: two eyes treated with Mitomycin C 0.02% over 2 min following the excision, and one eye treated with Mitomycin C and amniotic membrane transplantation after removal of the dermoid. Follow-up ranged from 2 to 53 months (median 17 months). Results Intraoperative complications did not occur in any of the patients. Postoperatively, all patients showed corneal reepithelialization within a week. Limbal stem cell deficiency with a pseudopterygium developed in four eyes, one treated with bare-sclera excision and the others with amniotic membrane transplantation. One pseudopterygium had to be removed surgically because of visual acuity deterioration. Not a single eye treated with Mitomycin C developed a pseudopterygium. Conclusions The transplantation of amniotic membrane following removal of a limbal dermoid cannot prevent the occurrence of a pseudopterygium. However, the use of Mitomycin C seems to have a protective effect.

Purpose: The posterior cornea is rotationally asymmetric, and Descemet membrane endothelial keratoplasty (DMEK) grafts preferentially scroll vertically. This prospective study assessed whether graft attachment after DMEK differed depending on the rotational alignment of the donor graft in the recipient eye. Methods: Pseudo-randomization and blinding of the graft orientation in the recipient's eye were possible by procedural separation: (1) The eye bank recorded the position of an orientation marker in the donor cornea; (2) the surgeon preparing the DMEK graft recorded an upside-down marker relative to the eye bank marker; and (3) the surgeon assessed the position of the upside-down marker in the recipient after DMEK. Surgeons were masked towards the eye bank marker. Using mixed-effects models, we assessed graft attachment relative to the rotational alignment of the donor graft. Results: Postoperatively, the graft was not fully attached in 59 of 179 eyes (33%). A second air fill (rebubbling) was performed in 11%. The graft axis was in line with the recipient cornea axis in 40%, oblique in 28% and orthogonal in 32%. We did not detect an elevated risk of incomplete attachment (odds ratio [OR], 1.16; 95% CI, 0.61-2.20), risk of rebubbling (OR, 1.25; 95% CI, or larger areas of graft detachment in non-aligned grafts compared to aligned grafts. Conclusion: Rotational alignment was not strongly associated with the risk of incomplete graft attachment, although modestly elevated risks cannot be ruled out. Efforts are needed to reduce the need for rebubbling after DMEK and to identify modifiable risk factors for graft detachment.

UVA crosslinking is used for treatment of corneal diseases such as keratoconus in order to stabilize the corneal tissue by crosslinking of the collagen fibers. It has been shown that the crosslinking treatment leads to a stiffening of the central corneal tissue. However, knowledge of lateral extent of the corneal stiffening as well as a systematic study of the mechanical response of human cornea is still missing. In our study we measured the stiffness (elastic modulus) of the anterior surface of healthy and crosslinked human corneas by instrumented indentation using a spherical indenter. The results show that the stiffness of the central and paracentral cornea increased almost two times after the crosslinking but the stiffening effect rapidly decreased towards the periphery of the radiation field. These new insights into the understanding of the biomechanical response of corneal crosslinking shall contribute to a better understanding and an optimization of this perspective medical treatment. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1413-1420, 2018.

Keratoconus leads to progressive thinning and protrusion of the cornea. Young patients exhibit the highest risk for progression. Corneal crosslinking was introduced in 1998 and is intended to prevent progression of keratoconus. Only a few prospective controlled trials have been published. Six randomised controlled trials have been published. All these trials confirmed the efficacy of crosslinking through keratometric data. In two trials, progression was reported in some patients of the treatment group. This indicates that not all patients benefit from corneal crosslinking. The risks of the procedure include corneal scarring, haze, endothelial cell damage and infections of the cornea. In order to avoid these risks, patients without progression should not be treated with crosslinking.

There is a growing interest in quality measurement in the healthcare sector. Hospitals in Germany are obligated to participate in measures for external quality assurance and they must establish an internal quality management system. In addition to the legal requirements, measurement of quality is also possible with routine data. Suitable sources are the ICD system or unstandardized information from treatment documentation. The selection of suitable quality indicators is necessary to interpret the data. Complications or achievement of surgical objectives can be suitable quality indicators. Analysis of procedures or the assessment of waiting time are also possible indicators. Our first data concerning waiting time show that with increasing use of an electronic patient guidance system, the waiting time decreased in our outpatient department. Assessment of quality indicators from routine data enables a continuous measurement of quality over a long period. Measures to increase quality can easily be checked. Routine data also provide the possibility to participate in a public reporting of quality indicators.