[Statistical analysis of correlated measurement data in ophthalmology : Tutorial for the application of the linear mixed model in SPSS and R using corneal biomechanical parameters]. / Statistische Auswertung korrelierter Messdaten in der Augenheilkunde : Tutorial zur Verwendung des linear gemischten Modells in SPSS und R anhand biomechanischer Parameter der Hornhaut.

BACKGROUND: In ophthalmology data from both eyes of a person are frequently included in statistical analyses. As correlated data are used this procedure contradicts the independency principle for classical statistical tests, such as Student's t­test and analysis of variance (ANOVA). In this tutorial a new possibility is presented in which data from both eyes can be used for statistical analysis. OBJECTIVE: The statistical approach of linear mixed models (LMM) was used to take correlated data of both eyes of patients into account. METHODS: The LMM is available in several statistical software packages, e.g. SPSS and R, and allows the inclusion of measurement data from both eyes of a person in the statistical analysis. The application was tested on data from a biomechanical characterization of the cornea from healthy participants assessed with the dynamic Scheimpflug analyzer (Corvis ST; Oculus, Wetzlar, Germany). RESULTS: A total of 158 eyes from 79 healthy participants were included. A strong correlation between the right and left eyes of the participants could be observed with respect to the analyzed parameters. Comparison of the biomechanical parameters between the different age groups showed that P-values were increased when using the LMM compared to the ANOVA. Older participants (56-79 years) showed a significantly shorter time to the second applanation (P = 0.002), a significantly increased eyeball movement during the deformation (P = 0.001) and a significantly higher stiffness at the first applanation (P = 0.006) compared to younger participants (18-35 years). CONCLUSION: The analysis of measurement data from both eyes using classical statistical tests, without the consideration of the correlation, leads to an overestimation of the statistical power. This can be avoided by implementation of the LMM.

[Dynamic Scheimpflug Analyzer (Corvis ST) for measurement of corneal biomechanical parameters : A praxis-related overview]. / Dynamischer Scheimpflug-Analyzer (Corvis ST) zur Bestimmung kornealer biomechanischer Parameter : Ein praxisbezogener Überblick.

BACKGROUND: Topographic and tomographic parameters alone are often not sufficient for early detection of corneal changes. Pathological alterations in the microstructure of the cornea occur before changes in topography and tomography can be detected. Biomechanical parameters show a strong correlation with microscopic structural changes. OBJECTIVE: The aim of the study was to gain information about the microscopic structure and consistency of the cornea by measuring biomechanical parameters. MATERIALS AND METHODS: The deformation behavior of the cornea was analyzed with the Dynamic Scheimpflug Analyzer (Corvis ST; OCULUS, Wetzlar, Germany). Deformation parameters and biomechanical indices were derived from the deformation response of the cornea. RESULTS: Deformation parameters and indices in keratoconus patients differ significantly from healthy subjects. Alterations of the cornea can be detected before topographic and tomographic changes occur. The repeatability and reproducibility of relevant deformation parameters is good to very good. In glaucoma patients a modified deformation behavior of the cornea can be observed, which might be related to structural changes. CONCLUSION: The Corvis ST allows a reliable characterization of the tissue structure and consistency of the cornea.

[Clinical Results of the Implantation of Two Types of Multifocal Rotational Asymmetric Intraocular Lenses]. / KLINICKÉ VÝSLEDKY IMPLANTACE DVOU TYPU MULTIFOKÁLNÍ ROTACNE ASYMETRICKÉ NITROOCNÍ COCKY.

PURPOSE: The aim of the study was evaluation and comparison of clinical results of two types of rotationally asymmetric multifocal intraocular lens (LENTIS Mplus and LENTIS MplusX). MATERIAL AND METHODS: The study included 247 eyes of 124 patients aged 25 - 76 years (mean, 58 years). After phacoemulsification multifocal intraocular lens LENTIS Mplus (group A, n = 141) or LENTIS MplusX (group B, n = 106) was implanted. Patients were divided into two groups according to the type of intraocular lens. Patients were evaluated at 1 month, 3 months and 6 months after surgery. We assessed the uncorrected visual acuity, best corrected visual acuity, subjective refraction, contrast sensitivity and subjective satisfaction. RESULTS: Mean preoperative monocular uncorrected distance visual acuity (UCDVA) in the group A was 0,40 ± 0,27; in the group B 0,34 ± 0,25. Postoperatively UCDVA was statistically significant improved in both groups (group A: 1,01 ± 0,20; group B: 0,90 ± 0,15). Mean preoperative monocular uncorrected near visual acuity (UCNVA) was Jaeger (J) 12,82 ± 4,16 (group A), resp. J 12,73 ± 3,99 (group B). Postoperatively UCNVA was statistically significant improved in both groups (group A: J 1,81 ± 1,42; group B: J 1,54 ± 1,72). There was not found statistically significant difference between both groups in these parameters. Contrast sensitivity was evaluated in patients who have undergone clear lens extraction in both eyes. There was not found the statistically significant reduction of contrast sensitivity in both groups. Subjective satisfaction was assessed in the range of marks 1-5. The average mark of the subjective satisfaction ratings in the group A was 1,37; in the group B 1,25. CONCLUSION: Our study found the multifocal intraocular lens LENTIS Mplus and LENTIS MplusX give high-quality distance and near vision and provide high degree of spectacle independence. There was not found statistically significant difference in all parameters between the Group A (implantation Mplus LENTIS) and the Group B (implantation LENTIS MplusX) in our study. However, in our study we have observed higher subjective satisfaction and lower incidence of optical phenomena in the Group of patients with the implantation of intraocular lens LENTIS MplusX.Key words: LENTIS Mplus, LENTIS MplusX, visual acuity, contrast sensitivity, optical phenomen.

[Severe Eyeball and Facial Skeletal Injuries Caused by Firefighting Sport]. / Schwerwiegende Augen- und Gesichtsskelettverletzungen beim Feuerwehrsport.

The aim of this work is to draw attention to possible injuries of the eye and the facial skeleton caused by firefighting sport. There was a group of 9 patients presented who were treated from 2006 to 2015 in the Department of Ophthalmology at the University Hospital in Pilsen and diagnosed with severe eyeball contusion after being hit by a jet of water and/or a water pipe. Three cases are presented in detail.

[Treatment of Keratoconus by Accelerated Cross-linking]. / Lécba keratokonu metodou akcelerovaného cross-linkingu.

This study evaluates the efficacy of treatment of progressive keratoconus using Accelerated Corneal Collagen cross-linking (ACXL) method. Patients underwent ACXL at the Dept. of Ophthalmology of University Hospital in Hradec Králové between 2012 - 2013. Uncorrected distance visual acuity, best corrected distance visual acuity, keratometry (K1, K2, Kmax), corneal astigmatism and corneal pachymetry were measured preoperatively and in 6 months, 1year, 2 and 3 years after the surgery. The results were statistically analysed by non-parametric Wilcoxon test. There were found statistically significant changes in K2 values and values of corneal thickness postoperatively.Key words: keratoconus, ectasia, accelerated corneal cross-linking.

[Corneal Cross-Linking with Riboflavin and UVA in Keratoconus]. / Hornhautvernetzung mit Riboflavin und UV-A-Licht bei Keratokonus.

Changes in the biomechanical properties of the human cornea play an important role in the pathogenesis of corneal ectatic diseases. Many different pathological conditions in the cornea may reduce its biomechanical resistance. Corneal collagen cross-linking (CXL) has emerged as a promising technique to slow or even to stop the progression of ectasia. In this procedure, riboflavin (vitamin B2) is administered in conjunction with ultraviolet A light (UVA, 365 nm). This interaction causes the formation of reactive oxygen species, leading to additional covalent bonds between collagen molecules, with consequent biomechanical stiffening of the cornea. Although this method is not yet accepted as an evidence-based treatment of corneal ectasia, the results of prospective, randomised studies of CXL used in the treatment of this pathological entity show significant changes in the properties of corneal tissue. This procedure is currently the only aetiopathogenetic treatment of ectatic eyes that can delay or stop the process of cornea destabilisation, reducing the necessity for keratoplasty. Despite promising results, CXL is associated with issues that include long-term safety and duration of the stabilising effect.

[Cross-Linking in Keratoconus: "Epi-off" or "Epi-on"?]. / Hornhautvernetzung beim Keratokonus: "Epi-off" oder "Epi-on"?

Corneal cross-linking can halt the progression of keratoconus, but what is the best approach for treatment? There are a number of treatment options for keratoconus, but only corneal cross-linking (CXL) appears to halt the progression of the disease. To guarantee effective cross-linking, CXL treatment involves removal of the corneal epithelium prior to riboflavin application and ultraviolet light illumination - "epi-off" CXL. Several methods of "epi-on" (transepithelial) CXL have been proposed, such as keeping the corneal epithelium intact which should be less painful and help avoid other CXL-associated adverse events. The evidence so far is that epi-off CXL remains the most effective method of strengthening the cornea and slowing keratoconus progression - but transepithelial methods are gaining ground.

[Corneal collagen cross-linking with riboflavin and ultraviolet-A light in progressive keratoconus. Results after 10-year follow-up]. / Hornhautkollagenvernetzung mit Riboflavin und UVA-Licht bei Patienten mit progressivem Keratokonus : 10-Jahres-Ergebnisse.

PURPOSE: Riboflavin and ultraviolet-A induced cross-linking (CXL) is a promising therapeutic option to halt the progression of keratoconus. The aim of the study was to prove a long-term stabilizing effect of riboflavin and ultraviolet-A induced collagen CXL in young and otherwise healthy patients with progressive keratoconus and a corneal thickness of at least 400 µm on average 10 years after treatment. METHODS: Corneal CXL was performed after removing epithelial tissue by instilling riboflavin 0.1% solution for 30 min before and during 30 min of ultraviolet-A irradiation (370 nm, 3 mW/cm(2)). This long-term retrospective study included 30 eyes of 20 patients with progressive keratoconus. Preoperative and postoperative examinations on average 10 years after treatment included best corrected visual acuity (BCVA), corneal topography (keratometry values KMAX, KMIN and KApex), corneal thickness (CT) and if available endothelial cell density. RESULTS: The mean preoperative age was 28 ± 7 years (range 14-42 years), 4 patients were female (7 eyes) and 16 patients (23 eyes) were male. Preoperatively, the mean K-value on the apex of keratoconus was 62 ± 13.2 dpt which showed a statistically significant reduction after 10 years to 55 ± 8.1 dpt (p = 0.001). The mean KMAX (53 ± 8.2 versus 49 ± 6.6 dpt) and KMIN values (48 ± 5.5 vs. 45 ± 5.1 dpt) also showed a statistically significant decrease (p = 0.001). In comparison BCVA also showed a statistically significant preoperative and postoperative difference (p = 0.005). There was a significant improvement of BCVA by a mean of - 0.13 ± 0.25 logMAR. The mean change in corneal thickness at the 10-year follow up was 46 µm (p = 0.001). Bias possibly occurred because of a change of the measurement method from ultrasound pachymetry to optical pachymetry with Oculus Pentacam®. Neither corneal endothelium nor deeper structures suffered any damage. Only two patients had continuous progression of keratoconus and needed a reapplication of CXL. CONCLUSION: The results of this study indicate that riboflavin and ultraviolet-A induced corneal CXL is a promising therapeutic option for progressing keratoconus to obtain long-term stabilization. There was a sustained improvement of all K-values and BCVA 10 years after treatment and CXL is minimally invasive and easy to handle. Side effects, such as endothelial damage did not occur.

[Bilateral visual loss in a young male patient]. / Bilaterale Visusminderung bei einem jungen Mann.

We present the case of a 36-year-old male patient who presented with an increasing bilateral loss of vision which had existed for several years. Slit-lamp examination revealed a conical anterior protusion of the lens and funduscopy showed a discreet perimacular dot and fleck retinopathy. In consideration of all clinical findings the patient was diagnosed with anterior lenticonus as an ocular manifestation of an Alport's syndrome which is a rare X-linked disease. Besides renal failure and hearing loss which occur early, ocular changes usually manifest later on. Patients with a anterior lenticonus can be effectively treated with phacoemulsification and intraocular lens implantation. The visual outcome after surgery is excellent.

[Corneal cross-linking with hypo-osmolar riboflavin solution for keratoconus with thin corneas]. / Hornhautvernetzung mit hypoosmolarer Riboflavin-Lösung beim Keratokonus mit dünner Hornhaut.

BACKGROUND: The aim of this study was to evaluate the 1-year results of 32 keratoconic eyes with thin corneas which were treated by hypo-osmolar riboflavin solution and ultraviolet A (UVA) collagen cross-linking (CXL). PATIENTS AND METHODS: Patients with progressive keratoconus and a corneal thickness (CT) less than 400 µm (without epithelium) were included in this study. The CT was measured with an ultrasound device (Tomey SP-3000, Nishi-ku, Nagoya, Japan). An increase in the maximum topographic K-value at the apex of keratoconus and a reduction in corneal thickness with or without changes in visual acuity (VA) within the last year were considered to be progression. A total of 32 eyes with an additional follow-up within 1 year were evaluated before and after the procedure. Examinations consisted of an evaluation of VA, corneal topography, slit-lamp microscopy and corneal thickness measurements. RESULTS: Preoperatively the mean corneal thickness (with epithelium) was 382.3±41.9 µm and after removal of the epithelium the thickness of the cornea was reduced to 337.0±51.9 µm. After the application of hypo-osmolar riboflavin solution the mean value increased to 451.8±46.7 µm. Preoperatively the mean K-value of the apex of the keratoconus was 65.6±11.2 dopters, and 1 year after treatment this value remained relatively unchanged at 64.9±11.0 diopters (P=0.839). Mean VA at the time of the treatment was 0.63±0.37 logMAR and 1 year after the treatment this value was not statistically different (0.59±0.42 logMAR; P=0.662). In the last follow-up examination 1 year after the procedure all corneas were transparent without any scarring lesions in the stroma. CONCLUSIONS: The results of this study using hypo-osmolar riboflavin solution in a cross-linking procedure for thin corneas showed a stability of keratoconus 1 year after CXL. Application of the hypo-osmolar riboflavin solution prevented cross-linked corneas from developing stromal scars.

[Corneal scar development after cross-linking in keratoconus]. / Narbenbildung nach Hornhautvernetzung beim Keratokonus.

BACKGROUND: Corneal scar development after riboflavin-UVA-induced corneal collagen cross-linking (CXL) was retrospectively evaluated. PATIENTS AND METHODS: A total of 163 CXL-treated eyes in 127 patients with stage 1-3 keratoconus according to Krumeich's classification were included in this retrospective analysis. The follow-up period was 1 year. At the first and at all follow-up examinations uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), biomicroscopic findings, corneal topography and corneal thickness were recorded. RESULTS: At 1 year following CXL, 149 eyes (91.4%) of 114 patients had a clear cornea without corneal scar (control group), while 14 eyes (8.6%) of 13 patients developed clinically significant corneal scar (scar group). Preoperatively, the mean K value of the apex was 62.1 ± 13.8 D in the control group and 71.1 ± 13.2 D in the scar group (P=.02). The mean value of corneal thickness before the procedure was 478.1 ± 52.4 µm in the control group and 420.0 ± 33.9 µm in the scar group (P=.001). The UCVA and BCVA, which were preoperatively similar between groups (P=.59, P=.75 respectively), were postoperatively improved in the control group (P=.023, P=.001 respectively), but reduced in the scar group (P=.012, P=.004 respectively). CONCLUSION: K-values and corneal thickness could be considered as predictive factors for the possible development of corneal scarring after riboflavin-UVA-induced CXL. Advanced keratoconus appears to be associated with a higher risk of corneal scar development due to lower corneal thickness, greater curvature and intrinsic tissue characteristics.

Mitomycin C for pterygium: long term evaluation.

AIM: To evaluate long term complications after pterygium excision with mitomycin C (MMC) application. DESIGN: Prospective non-comparative interventional case series. PARTICIPANTS: Ninety nine patients who underwent pterygium surgery and participated in a controlled study for efficacy of MMC for pterygium surgery between 1989 and 1994. METHODS: Patients who were located and agreed to come for examination underwent a complete eye examination. The bare sclera area, in particular, was examined for possible complications. The main outcome measures were anatomical findings in area of MMC application. RESULTS: Forty three eyes of 43 patients were examined. Sixty three per cent of patients had pterygium surgery with intraoperative application of 0.02% MMC for 5 minutes and 37% of patients received MMC 1% or 2% drops four times daily for 2 weeks postoperatively. In three patients, pterygium recurred within 18 months. The only complication was mild conjunctival avascularity in areas of pterygium excision in 30% of patients. CONCLUSION: Long term evaluation revealed that the use of MMC in pterygium surgery is safe, but for a strict selection of patients, controlled use of MMC and long term follow up are required.