Impact of DMEK on visual quality in patients with Fuchs' endothelial dystrophy.

PURPOSE: To investigate short-term (3 months follow-up) changes in visual quality following Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial dystrophy (FED). METHODS: In this prospective institutional case series, 51 patients that underwent DMEK for FED were included. Assessment included the Quality of Vision (QoV) questionnaire preoperatively, at 1 month, and 3 months after surgery. Secondary outcome measures were anterior segment parameters acquired by Scheimpflug imaging, corrected distance visual acuity (CDVA), and endothelial cell density (ECD). RESULTS: Glare, hazy vision, blurred vision, and daily fluctuation in vision were the symptoms mostly reported preoperatively. All symptoms demonstrated a significant reduction of item scores for severity, frequency, and bothersome in the course after DMEK (P < 0.01). Glare and fluctuation in vision remained to some extent during the follow-up period (median score = 1). Preoperatively, corneal densitometry correlated moderately to weakly with severity of hazy vision (rs = 0.39; P = 0.03) and frequency (rs = 0.26; P = 0.02) as well as severity (rs = 0.27; P = 0.03) of blurry vision. CDVA and central corneal thickness (CCT) did not correlate with visual complains. CONCLUSIONS: Following DMEK for FED, patient-reported visual symptoms assessed by the QoV questionnaire represent a useful tool providing valuable information on the impact of DMEK on visual quality that cannot be directly estimated by morphological parameters and visual acuity only.

Influence of rebubbling on anterior segment parameters and refractive outcomes in eyes with DMEK for Fuchs endothelial dystrophy.

PURPOSE: To evaluate the potential impact of rebubbling on the anterior segment parameters and refractive outcomes in patients with graft detachment following uneventful DMEK for Fuchs endothelial dystrophy (FED). METHODS: Retrospective institutional cohort study of comparing 34 eyes of 31 patients with rebubbling for graft detachment following Descemet membrane endothelial keratoplasty (DMEK) to 33 eyes of 28 patients with uneventful DMEK. Main outcome parameters were various corneal parameters obtained by Scheimpflug imaging, refractive outcome, corrected distance visual acuity (CDVA), and endothelial cell density (ECD). RESULTS: Anterior and posterior corneal astigmatism, corneal densitometry, central corneal thickness, and anterior chamber depth and volume showed no significant differences. Preoperative distribution of astigmatism axis orientations showed a high proportion of anterior corneal with-the-rule astigmatism (71%) in eyes requiring rebubbling. Mean postoperative cylinder in the rebubbling group (1.21 ± 0.85 D) was significantly higher compared to the controls (p = 0.04), while differences in spherical equivalent (SE) were insignificant (p = 0.24). Postoperative CDVA was 0.11 ± 0.11 in the control group compared to 0.21 ± 0.17 in the rebubbling group (p = 0.03). Eyes with subsequent rebubbling demonstrated a significantly higher endothelial cell loss (56% versus 37%) (p < 0.001). CONCLUSION: Apart from higher cylinder values, refractive outcome and corneal parameters assessed by Scheimpflug imaging were comparable in eyes with rebubbling and controls. However, a reduced visual acuity and an increased endothelial cell loss should be taken into consideration prior to rebubbling especially in eyes with circumscribed graft detachment.

Refractive outcome and tomographic changes after Descemet membrane endothelial keratoplasty in pseudophakic eyes with Fuchs' endothelial dystrophy.

PURPOSE: To analyze refractive and topographic changes secondary to Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes with Fuchs' endothelial dystrophy (FED). METHODS: Eighty-seven pseudophakic eyes of 74 patients who underwent subsequent DMEK surgery for corneal endothelial decompensation and associated visual impairment were included. Median post-operative follow-up time was 12 months (range: 3-26 months). Main outcome measures were pre- and post-operative manifest refraction, anterior and posterior corneal astigmatism, simulated keratometry (CASimK) and Q value obtained by Scheimpflug imaging. Secondary outcome measures included corrected distance visual acuity (CDVA), central corneal densitometry, central corneal thickness, corneal volume (CV), anterior chamber volume (ACV) and anterior chamber depth (ACD). RESULTS: After DMEK surgery, mean pre-operative spherical equivalent (± SD) changed from + 0.04 ± 1.73 D to + 0.37 ± 1.30 D post-operatively (p = 0.06). CDVA, proportion of emmetropic eyes, ACV and ACD increased significantly during follow-up. There was also a significant decrease in posterior corneal astigmatism, central corneal densitometry, central corneal thickness and corneal volume over time (p = 0.001). Only anterior corneal astigmatism and simulated keratometry (CASimK) remained fairly stable after DMEK. CONCLUSION: Despite tendencies toward a hyperopic shift, changes in SE were not significant and refraction remained overall stable in pseudophakic patients undergoing DMEK for FED. Analysis of corneal parameters by Scheimpflug imaging mainly revealed changes in posterior corneal astigmatism pointing out the relevance of posterior corneal profile changes during edema resolution after DMEK.

Validation of Spiked Postmortem Blood Samples from Cornea Donors on the Abbott ARCHITECT and m2000 Systems for Viral Infections.

BACKGROUND: Transplantation of human corneal tissue is associated with the potential risk of transmittance of viral infections. In accordance with European directives and federal laws, in Germany each tissue donor has to be tested for infectious diseases such as hepatitis B and C virus (HBV and HCV) and human immunodeficiency virus (HIV) infection. However, most of the currently available CE-marked serologic and nucleic acid screening systems are only validated for antemortem blood. METHODS: Twenty related and paired ante- and postmortem blood samples from cornea donors were obtained and subsequently analyzed for hepatitis B surface antigen (HBsAg), hepatitis B antibody (anti-HBc), anti-HCV, HCV RNA, anti-HIV-1/2, and HIV p24 Ag using Abbott test systems. The sera were also spiked with reference materials in concentrations giving low and high positivity for HBV, HCV, and HIV markers. RESULTS: The spiked ante- and postmortem sera from related donors showed similar results for HBsAg, anti-HBc, anti-HCV, HCV RNA, anti-HIV, and HIV p24 Ag, indicating a high stability of viral markers in cadaveric specimens. Three cornea donors had a medical history of HBV infection and revealed anti-HBc at similar levels in the ante- and postmortem sera. In addition, there was a single postmortem sample demonstrating a weak signal of anti-HIV-1 and HIV-1 p24 Ag. False-positive or false-negative results were not detected. The results obtained with the Abbott ARCHITECT analyzer and Abbott RealTime HCV PCR showed no significant differences. CONCLUSION: The analyzed screening assays are suitable for the detection of infectious markers of HBV, HCV, and HIV at similar levels in spiked ante- and postmortem sera from cornea donors.

Effects of ranibizumab (Lucentis®) and bevacizumab (Avastin®) on human corneal endothelial cells.

BACKGROUND: Ingrowth of newly formed blood and lymph vessels (angiogenesis) from the limbus region into the cornea can be treated successfully by subconjunctival application of antiangiogenic agents. Currently, there are several angiogenesis inhibitors from various manufacturers available, such as vascular endothelial growth factor (VEGF) antibodies. The aim of the study was to investigate potential cytotoxic effects of two anti-VEGF agents, ranibizumab (Lucentis®) and bevacizumab (Avastin®) on the human corneal endothelium. METHODS: Human donor corneas, not suitable for corneal transplantation, were organ-cultured in the presence of either ranibizumab (Lucentis®) or bevacizumab (Avastin®) at different concentrations (group 1: 250 µg / ml, group 2: 25 µg / ml, group 3: 2.5 µg / ml) for a period of up to 4 weeks. Microscopic imaging for endothelial cell counting, detection of morphologic alterations of the endothelium, and molecular biology testing (Enzyme-linked Immunosorbent Assay [ELISA]) for metabolic changes was performed. RESULTS: Background-corrected results showed neither a significant lactate dehydrogenase (LDH) change with increasing culturing time nor a significant difference between ranibizumab (Lucentis®) and bevacizumab (Avastin®) treatment. The endothelial cell density revealed also no statistically significant difference between the two treatment groups with ranibizumab (Lucentis®) and bevacizumab (Avastin®) at all concentrations tested in this study. CONCLUSIONS: In this study, the anti-angiogenic agents ranibizumab (Lucentis®) and bevacizumab (Avastin®) demonstrated no cytotoxic effects on the corneal endothelium of human organ-cultured donor corneas over the limited study time period of 4 weeks. However, based on the study design (in-vitro) and the limited follow-up period, no conclusions on potential long-term effects can be drawn.

[Microbial keratitis: Understand, recognize, and treat - part 1: General aspects and characteristics of bacterial keratitis]. / Mikrobielle Keratitis, Teil 1: allgemeine Aspekte und bakterielle Keratitiden.

Infectious inflammation of the cornea (microbial keratitis) represents a potentially vision threatening disease. Depending on the infectious agent and the course of the disease it can result in a complete loss of the involved eye. Early diagnosis and accurate treatment are mandatory to maintain a sufficient visual acuity. The purpose of this review is to highlight and discuss characteristic clinical features, diagnostic procedures, and therapeutic aspects of three major forms of microbial keratitis (bacteria, fungi, and acanthamoeba; the latter two in the 2nd part of this article).

Distribution of pseudoexfoliation material on anterior segment structures in human autopsy eyes after cataract surgery with intraocular lens implantation.

The purpose of the study was to evaluate the distribution and amount of pseudoexfoliation material (PXM) on anterior segment structures in pseudophakic human autopsy eyes with pseudoexfoliation (PEX) syndrome and to study its impact on fixation and decentration of posterior chamber intraocular lenses (IOLs). Sixteen human autopsy eyes (donor age [mean ± SD] 77.5 ± 8.6 years; range, 70-90 years) with history of cataract surgery and PEX syndrome were analyzed for distribution and accumulation of PXM on structures of the anterior segment by light microscopy. Quantitative IOL decentration measurements were performed using the Miyake-Apple posterior view technique. All 16 eyes displayed IOLs which were either fixed symmetrically in the capsular bag (n = 8) or asymmetrically with one haptic in the sulcus and one in the bag (n = 7) or at the pars plicata of the ciliary body (n = 1). In the majority, PXM was found around the pars plicata (average grade: 1.6 ± 0.53 µm) and the lens capsule (average grade: 1.05 ± 0.46 µm). Minor amounts were detected at the pars plana and the trabecular meshwork. IOL decentration measurements ranged from 0.51 ± 0.35 (symmetrical-fixation) to 0.61 ± 0.43 mm (asymmetrical-fixation). There was only a weak statistically not significant correlation in regard to the amount of PXM and IOL decentration and between PXM distribution and the IOL fixation site. PXM contributes to weakening of the suspensory apparatus of the crystalline lens. Although PXM induced tissue alterations predispose for a broad spectrum of intra- and postoperative complications, the amount and distribution of PXM on different anterior segment structures showed only a weak correlation to IOL decentration or fixation location.

Anterior Segment Biometry in a Caucasian Population with Cataracts.

PURPOSE: To investigate biometric factors of the anterior segment of phakic eyes with cataracts. METHODS: This population-based study included Caucasian patients with cataracts in the University Eye Hospital, Goethe University Frankfurt, Germany. Biometric parameters were measured using the swept-source optical coherence tomography method. Patients were grouped into intermediate stages based on decades of life. RESULTS: In total, 6289 eyes of 3615 patients (age: 70.67 ± 8.42 years) were included. Age-related reductions in the anterior chamber depth (mean ± standard deviation) decreased from 3.26 ± 0.42 mm (group A: 55-59 years) to 2.94 ± 0.4 mm (group G: 85-89 years), and those in the axial length decreased from 24.37 ± 1.87 mm (group A) to 23.39 ± 1.07 mm (group G). Likewise, the white-to-white distance decreased from 12.12 ± 0.48 mm (group A) to 11.96 ± 0.47 mm (group G). Lens thickness tended to increase accordingly from 4.39 ± 0.36 µm (group A) to 4.9 ± 0.40 µm (group G). A comparison of the eyes showed no detectable lateral difference regarding the biometric parameters between the groups (axial length: p = 0.26, Rosenthal effect size = 0.03; lens thickness: p = 0.12, R = 0.03; anterior chamber depth: p = 0.63, Rosenthal effect size = 0.01). The axial length and anterior chamber depth differed significantly between sexes (r = 0.22, p < 0.0001 and r = 0.16, p < 0.0001, respectively). Multiple regression analysis of the anterior chamber depth as a function of biometry parameters as well as age and sex additionally indicated a positive correlation of anterior chamber depth with white-to-white distance (b = 0.32, p = 10-5), axial length (b = 0.10, p = 10-5), keratometry (b = 0.07, p = 10-5), and lens thickness (b=-0.05, p = 10-5) with a high effect size (Cohen f2=1.866, p = 10-5) and strong multiple correlation coefficient (Rosenthal effect size = 0.80, p = 10-5). CONCLUSIONS: In the anterior segment, there are age- and sex-dependent changes in biometric parameters. In addition, changes in anterior chamber depth were noted in relation to white-to-white distance, axial length, keratometry, and lens thickness. These data should be considered in lens calculation formulas.

Association between anterior chamber biometry and posterior capsular defects.

PURPOSE: To analyze the association between anterior chamber biometric factors and posterior capsular defects (PCDs) that occur during extracapsular cataract extraction. SETTING: University Eye Hospital, Goethe University Frankfurt, Germany. DESIGN: Population-based study. PATIENTS AND METHODS: Extracapsular cataract extractions for inpatient cases within 4 years were retrospectively analyzed. The data on the occurrence of PCDs, age, sex, surgeon, and biometry were obtained. For cases with PCDs, the secondary ocular diseases, number of procedures, lens implant, visual acuity, and course were also recorded. Swept-source optical coherence tomography measurements allowed the measurement of lens thickness (LT) in addition to the usual biometry values. RESULTS: A total of 1967 cataract surgeries (patients age: 70.56 ± 8.42, 1005 women; 962 men) were included, and PCDs were documented for 59 (2.54%; 31 women, 28 men) cases (patient age: 70.95 ± 8.52 years). There were no differences ( P = .76) related to the surgeons (n = 9) with minimal effect sizes. The mean LT, axial length, corneal curvature, and anterior chamber depth were 4950.36 ± 466.63 µm, 23.73 ± 1.77 mm, 43.89 ± 1.36 diopters, and 3.02 ± 0.71 mm, respectively. The Wilcoxon-Mann-Whitney test showed significant associations between LT ( P = .01) and PCDs with moderate relevance for the Rosenthal effect size (LT R = 0.34; ACD R = 0.29). CONCLUSIONS: In addition to ACD, a tendency for the occurrence of PCD could be proven, especially for LT. Therefore, special attention should be paid to LT preoperatively for comprehensive risk stratification.

[Combination of simulation-based and online learning in ophthalmology : Efficiency of simulation in combination with independent online learning within the framework of EyesiNet in student education]. / Kombination von simulationsbasiertem Lernen und Online-Learning in der Augenheilkunde : Effizienz von Simulation in Kombination mit eigenständigem Online-Learning im Rahmen von EyesiNet in der studentischen Ausbildung.

BACKGROUND: Ophthalmoscopy is part of the medical curriculum but the teaching of medical contents is often unsatisfactory. No systematic learning of pathologies and their treatment options is possible because appropriate patient populations are often unavailable; instead of that healthy students examine each other. For this reason, we have developed a project to improve teaching at the medical faculty of the JWG University in Frankfurt/Main, which offers the opportunity for training in ophthalmoscopy using a newly developed online platform (EyesiNet) in addition to simulator training. Defined learning contents are reproducible and made equally available to everyone. AIM: The aim of this study was to evaluate a format for improving the teaching of direct and indirect ophthalmoscopy for students. Practical exercises on virtual reality-based simulators were intertwined with newly developed theoretical content adapted to the teaching catalog in the online platform EyesiNet. MATERIAL AND METHODS: On the first and last days of the internship, the students worked on cases in Eyesi Direct and Eyesi Indirect. In the meantime, they were able to deal with the theoretical basics of these ophthalmological clinical pictures in the web-based EyesiNet on a voluntary basis. RESULTS: Eyesi Direct: with p = 0.29, both groups had the same state of knowledge and did not have significantly different results in case processing on the first day of the internship. In the group without training (n = 54), a significant improvement in simulator training was observed on the last day of the practical training with p = 0.02 but with a small effect size of 0.1. Among the trainees (n = 32) a highly significant improvement with an effect size of 0.3 was observed with p = 0.0004. Eyesi Indirect: both groups had no significant difference in the stage of knowledge in the Eyesi Indirect at the beginning of the training period (p = 0.10). After training both groups performed slightly better but without significance (without training p = 0.41/with training p = 0.17). CONCLUSION: The online platform EyesiNet supports the learning of the most important disease patterns. Learning contents are made available in a reproducible and standardized way for all students. The skills of direct ophthalmoscopy can be learned much faster than those of indirect ophthalmoscopy.

Refractive surgery trends and practice style changes in Germany over a 3-year period.

PURPOSE: To study the current practice styles and preferences of refractive surgeons in Germany. METHODS: In February 2008, a seven-item questionnaire regarding the practice of refractive surgery was mailed to 282 members of the German Society of Intra-ocular Lens Implantation, Interventional, and Refractive Surgery (DGII) and the Commission of Refractive Surgery (KRC). Most questions were identical to our 2005 German refractive surgery survey. All data were analyzed in a masked fashion. RESULTS: The response rate was 42.2%. The majority (68%) of respondents reported that they perform refractive surgery in laser centers (exclusively or partially) followed by general hospitals (19.4%) and universities (12.6%). Although LASIK was the predominant type of refractive surgery performed (80.6%), other refractive procedures included refractive lens exchange (60.2%), photorefractive keratectomy (47.6%), phakic intraocular lens implants (45.6%), laser-assisted subepithelial keratectomy (36.9%), epithelial laser in situ keratomileusis (15.5%), intracorneal rings (5.8%), and limbal relaxing incisions (2.9%). The volume of refractive surgery procedures and the preferred type of excimer laser systems, microkeratomes, and diagnostic devices varied at different institutions. Most respondents performed either wavefront-guided custom ablation or wavefront-optimized ablation (63.1%) compared with conventional excimer laser correction (36.9%). CONCLUSIONS: Refractive surgery practice styles and preferences in Germany are comparable to trends in other European countries. Although LASIK is the most commonly performed refractive procedure, the numbers of various surface ablation techniques and refractive intraocular lens procedures are increasing.

[Ophthalmological care of SARS-CoV-2 positive patients in intensive care units]. / Ophthalmologische Betreuung von stationären, intensivpflichtigen SARS-CoV-2-positiven Patienten.

Early ophthalmological care of patients in intensive care with SARS-CoV­2 (Severe-Acute-Respiratory-Syndrom-Corona-Virus-2) infections is very time-consuming; however, this approach might prevent other ophthalmological diseases, such as lagophthalmos. There is no difference in ophthalmological treatment between SARS-CoV­2 positive and other intensive care patients. Due to the small number of cases in our observational study, a specific ophthalmological clinical pattern related to SARS-CoV­2 infections cannot currently be identified; however, the increased occurrence of subconjunctival hemorrhage in intensive care SARS-CoV­2 patients is remarkable. It remains unclear how ocular symptoms in SARS-CoV­2 infections are related or how they occur in different stages of the disease. Therefore, further studies are necessary for representative statements.

Modulation of choroidal neovascularization by subretinal injection of retinal pigment epithelium and polystyrene microbeads.

PURPOSE: The study was conducted to create a rapidly developing and reproducible animal model of subretinal choroidal neovascularization (CNV) that allows a time-dependent evaluation of growth dynamics, histopathologic features, and cytokine expression. METHODS: C57BL/6 and chemoattractant leukocyte protein-2 deficient (DeltaCcl-2) mice were studied. Mice received single or combined subretinal injections of cultured retinal pigment epithelium (RPE; C57BL/6-derived), polystyrene microbeads, or phosphate buffer solution (PBS). Fluorescence angiograms were performed over a period of 3 weeks. Mice were euthanized on post inoculation day 3, 7, 10, 14, or 21, and their eyes were evaluated by light, confocal, and electron microscopy. RESULTS: CNV membranes occurred in all study groups with an overall incidence of 94.3%. They extended in the subretinal space through central breaks in Bruch's membrane. CNV lesions were characterized by dynamic changes such as initiation, active inflammatory, and involution stages. CNV thickness peaked around PI day 7 and was greater in mice that received combined injections of RPE and microbeads or RPE cells alone. Small lesions developed in the control groups (microbeads or PBS only), in DeltaCcl-2, and old C57BL/6 mice. Variable expression of cytokines and growth factors was detected within the membranes. CONCLUSIONS: Our murine model represents a reliable approach inducing CNV growth by subretinal injection of either RPE cells alone or RPE cells and microbeads. The development of CNV lesions is a dynamic process that relies in part on macrophage trafficking and age.

Corneal Densitometry After Secondary Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To evaluate Scheimpflug corneal densitometry (CD) in patients undergoing secondary Descemet membrane endothelial keratoplasty (DMEK) after previous Descemet stripping automated endothelial keratoplasty or DMEK surgery. METHODS: This was a retrospective institutional case series of 37 eyes of 37 patients. Two secondary DMEK groups, group 1A (n = 12 DMEK after Descemet stripping automated endothelial keratoplasty), group 1B (n = 11 repeat DMEK), and group 2 (n = 14 primary DMEK for Fuchs endothelial dystrophy) were formed. CD was obtained preoperatively, 1, 6, and 12 months postoperatively. In addition, corrected distance visual acuity, central corneal thickness, and endothelial cell density were assessed. RESULTS: A significant decrease in grayscale units was observed in the 0- to 2-mm and 2- to 6-mm zones in all groups. For the 0- to 2-mm zone, values decreased from 49.11 ± 17.96 preoperatively to 22.87 ± 5.24 at 12 months (group 1A), from 45.16 ± 9.22 to 24.53 ± 14.21 (group 1B), and from 27.90 ± 8.30 to 16.64 ± 1.51 (group 2) (P < 0.01). Group 2 showed significantly lower grayscale units than groups 1A and 1B preoperatively and 12 months postoperatively in the 0- to 2-mm and 2- to 6-mm zones. Significant correlations of CD and corrected distance visual acuity were found in groups 1A and 1B in the 0- to 2-mm zone at 12 months. There were no significant correlations between CD and central corneal thickness postoperatively. CONCLUSIONS: A decrease in CD could be demonstrated in secondary DMEK. Nevertheless, CD values remained significantly higher than in controls. This might point out the relevance of secondary corneal structural changes.

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.

Comparison of standard and accelerated corneal cross-linking for the treatment of keratoconus: a meta-analysis.

PURPOSE: To compare results between standard and accelerated corneal collagen cross-linking (CXL) for the treatment of progressive keratoconus. METHODS: We performed literature searches in PubMed, Cochrane Library, Web of Science, ISRCTN registry, ClinicalTrials.gov, and EMBASE for studies comparing conventional Dresden (C-CXL) and accelerated CXL (A-CXL). Outcomes were clinical results and changes in corneal properties. Weighted mean differences were used to evaluate the effects. RESULTS: Here, 22 studies with 1158 eyes (C-CXL: 577 eyes; A-CXL: 581 eyes) were included. At the last follow-up, C-CXL was superior regarding minimum keratometry (p < 0.00001) and demarcation line depth (p < 0.00001), whereas A-CXL should be favoured when considering minimum corneal thickness (p = 0.0005). No differences in uncorrected and corrected distance visual acuity (p = 0.09 and 0.98), spherical equivalent (p = 0.11), spherical and cylindrical error (p = 0.29 and 0.32), maximal and average keratometry (p = 0.05 and 0.65), central corneal thickness (p = 0.15), corneal biomechanical properties (p ≥ 0.21 respectively), time of reepithelialization (p = 0.76), subbasal nerve density (p = 0.69), endothelial cell density (p = 0.30) and morphology (p ≥ 0.40 respectively) were found among both groups. CONCLUSION: Consideration of less corneal thinning favours A-CXL, whereas the deeper demarcation line and greater changes in minimum keratometric values in C-CXL may indicate a higher treatment efficacy. Altogether, C-CXL, as well as A-CXL, provides successful results in the strengthening of corneal tissue.

Evaluation of keratoconus progression.

AIM: To define variables for the evaluation of keratoconus progression and to determine cut-off values. METHODS: In this retrospective cohort study (2010-2016), 265 eyes of 165 patients diagnosed with keratoconus underwent two Scheimpflug measurements (Pentacam) that took place 1 year apart ±3 months. Variables used for keratoconus detection were evaluated for progression and a correlation analysis was performed. By logistic regression analysis, a keratoconus progression index (KPI) was defined. Receiver-operating characteristic curve (ROC) analysis was performed and Youden Index calculated to determine cut-off values. RESULTS: Variables used for keratoconus detection showed a weak correlation with each other (eg, correlation r=0.245 between RPImin and Kmax, p<0.001). Therefore, we used parameters that took several variables into consideration (eg, D-index, index of surface variance, index for height asymmetry, KPI). KPI was defined by logistic regression and consisted of a Pachymin coefficient of -0.78 (p=0.001), a maximum elevation of back surface coefficient of 0.27 and coefficient of corneal curvature at the zone 3 mm away from the thinnest point on the posterior corneal surface of -12.44 (both p<0.001). The two variables with the highest Youden Index in the ROC analysis were D-index and KPI: D-index had a cut-off of 0.4175 (70.6% sensitivity) and Youden Index of 0.606. Cut-off for KPI was -0.78196 (84.7% sensitivity) and a Youden Index of 0.747; both 90% specificity. CONCLUSIONS: Keratoconus progression should be defined by evaluating parameters that consider several corneal changes; we suggest D-index and KPI to detect progression.