Vergleich von konventionellen und wellenfront-basierten Maßzahlen zur Erkennung des frühen Keratokonus

Hintergrund: Die Unterschidung von Augen mit frühem Keratokonus (KC) von normalen Augen bereitet nach wie vor Schwierigkeiten. Die vorliegende Untersuchung vergleicht konventionelle keratometrie-basierte mit wellenfront-basierten Maßzahlen hinsichtlich ihrer Eignung, normale Augen von Augen mit sehr frühem Keratokonus zu unterscheiden. Methoden: Es wurden 17 Augen von 17 Patienten mit frühem KC eingeschlossen. Bei diesen 17 Augen handelt es sich um klinisch unauffällige Partneraugen des stärker betroffenen Auges. 123 Normalaugen von 69 Patienten dienten als Negativkontrolle. Von den axialen Kurvaturdaten wurden folgende Maßzahlen berechnet: zentrale Keratometrie (cK), Astigmatismus (AST), inferior-superiore Brechwertdifferenz (I-S), Verkippung der radialen Achsen (SRAX), KISA% index (eine Maßzahl, die auf cK, AST, I-S und SRAX basiert) und corneale Zernike-Koeffizienten (1.–7. Ordnung, Pupillendurchmesser: 6 mm). Aus Zernike-Koeffizienten wurden Diskriminanzfunktionen konstruiert. Receiver-Operatiing-Charakteristik (ROC)-Kurven wurden erstellt, um die diagnostische Trennschärfe dieser Werte zur Unterscheidung von klinisch unauffälligen Partneraugen von Augen mit frühem Keratokonus und normalen Kontrollen zu evaluieren. Ergebnisse: Der I-S-Wert (Korrektheit 92,1%, kritischer Wert 0,59 D) und die vertikale Coma (C3-1; 96,7%, –0,2 µm) waren die beiden Einzelwerte mit höchster Trennschärfe. Mit den ursprünglich publizierten kritischen Werten lag der Rabinowitz-McDonnell test (cK und I-S) bei 83,3% (Sensitivität 0%, Spezifität 100%) und der KISA% bei 70,8% (81,3%, 60,3%). In Verbindung mit Diskriminanzanalyse errichten Zernike-Koeffizienten eine Korrektheit von 96,7% (100%, 93,4%). Schlussfolgerungen: Auf cornealen Zernike-Koeffizienten basierende Maßzahlen erreichte die höchste Trennschärfe bei der Unterscheidung von Augen mit subklinischem KC von Normalaugen. Dennoch konnten konventionelle KC-indices eine ähnlich hohe Trenschärfe wie die Zernike-Methode erreichen, wenn die kritischen Werte entsprechend angepasst werden

Topical rosiglitazone is an effective anti-scarring agent in the cornea

Corneal scarring remains a major cause of blindness world-wide, with limited treatment options, all of which have side-effects. Here, we tested the hypothesis that topical application of Rosiglitazone, a Thiazolidinedione and ligand of peroxisome proliferator activated receptor gamma (PPARγ), can effectively block scar formation in a cat model of corneal damage. Adult cats underwent bilateral epithelial debridement followed by excimer laser ablation of the central corneal stroma to a depth of ~160 µm as a means of experimentally inducing a reproducible wound. Eyes were then left untreated, or received 50 µl of either 10 µM Rosiglitazone in DMSO/Celluvisc, DMSO/Celluvisc vehicle or Celluvisc vehicle twice daily for 2 weeks. Cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and post-mortem immunohistochemistry for alpha smooth muscle actin (αSMA). Impacts of the wound and treatments on optical quality were assessed using wavefront sensing and optical coherence tomography at 2, 4, 8 and 12 weeks post-operatively. In parallel, cat corneal fibroblasts were cultured to assess the effects of Rosiglitazone on TGFβ-induced αSMA expression. Topical application of Rosiglitazone to cat eyes after injury decreased αSMA expression and haze, as well as the induction of lower-order and residual, higher-order wavefront aberrations compared to vehicle-treated eyes. Rosiglitazone also inhibited TGFβ-induced αSMA expression in cultured corneal fibroblasts. In conclusion, Rosiglitazone effectively controlled corneal fibrosis in vivo and in vitro, while restoring corneal thickness and optics. Its topical application may represent an effective, new avenue for the prevention of corneal scarring with distinct advantages for pathologically thin corneas

Ein Programm zur automatisierten Linsendensitometrie von Scheimpflug-Bildern

Hintergrund: Im Rahmen der Erforschung von Mechanismen der Presbyopie-Entstehung hat das Interesse an Methoden zur Linsendensitometrie wieder zugenommen. Für spezielle Fragestellungen sind flexible Untersuchungsmethoden notwendig. Methoden: Basierend auf Aufnahmen mit der Scheimpflug-Kamera Pentacam HR (Oculus, Wetzlar) wurde ein MATLAB-Programm (V7.0, The MathWorks) erstellt, um größere Datenmengen automatisiert auszuwerten. Die Erkennung der Pupillenmitte als Referenzpunkt erfolgt mittels eines Randerkennungsalgorithmus. Als Kennzahlen dienen klassische Parameter der beschreibenden Statistik (Mittel, Minimum, Maximum, Standardabweichung und Variationskoeffizient) für einen definierten rechteckigen Bereich und für die zentrale vertikale Achse. Ergebnisse: In einer Präliminarserie von 18 Augen war eine automatisierte Messung mit korrekter Pupillenerkennung in 80% der Fälle möglich. Verglichen mit der hersteller-eigenen Software (Pentacam 6.03r11) besitzt das eigene Programm eine erweiterte Spannweite der Messwerte. Die Messwerte können automatisch nach Excel (Microsoft) exportiert werden. Ein modularer Aufbau ermöglicht eine flexible Erweiterung für weitere Fragestellungen (z.B. Quantifizierung von Kern- und Rindentrübungen). Schlussfolgerungen: Mittels eines selbst programmierten MATLAB-basierten Programmes kann eine automatisierte Messung und Analyse von linsndensitometrischen Parametern durchgeführt werden

The Effect of the Asphericity of Myopic Laser Ablation Profiles on the Induction of Wavefront Aberrations

A PMMA model study showed that spherical aberration induction in laser refractive surgery is due to loss of ablation efficiency in the corneal periphery. Aspheric ablation induced less spherical aberration and provided better theoretical image quality

Integration of Scheimpflug-Based corneal tomography and biomechanical assessments for enhancing ectasia detection

PURPOSE: To present the Tomographic and Biomechanical Index (TBI), which combines Scheimpflugbased corneal tomography and biomechanics for enhancing ectasia detection. METHODS: Patients from different continents were retrospectively studied. The normal group included 1 eye randomly selected from 480 patients with normal corneas and the keratoconus group included 1 eye randomly selected from 204 patients with keratoconus. There were two groups: 72 ectatic eyes with no surgery from 94 patients with very asymmetric ectasia (VAE-E group) and the fellow eyes of these patients with normal topography (VAE-NT group). Pentacam HR and Corvis ST (Oculus Optikgerate GmbH, Wetzlar, Germany) parameters were analyzed and combined using different artificial intelligence methods. The accuracies for detecting ectasia of the Belin/Ambresio Deviation (BAD-D) and Corvis Biomechanical Index (CBI) were compared to the TBI, considering the areas under receiver operating characteristic curves (AUROCs). RESULTS: The random forest method with leave-oneout cross-validation (RF/LOOCV) provided the best artificial intelligence model. The AUROC for detecting ectasia (keratoconus, VAE-E, and VAE-NT groups) of the TBI was 0.996, which was statistically higher (DeLong et al., P < .001) than the BAD-D (0.956) and CBI (0.936). The TBI cut-off value of 0.79 provided 100% sensitivity for detecting clinical ectasia (keratoconus and VAE-E groups) with 100% specificity. The AUROCs for the TBI, BAD-D, and CBI were 0.985, 0.839, and 0.822 in the VAE-NT group (DeLong et al., P <.001). An optimized TBI cut-off value of 0.29 provided 90.4% sensitivity with 96% specificity in the VAE-NT group. CONCLUSIONS: The TBI generated by the RF/LOOCV provided greater accuracy for detecting ectasia than other techniques. The TBI was sensitive for detecting subclinical (fruste) ectasia among eyes with normal topography in very asymmetric patients. The TBI may also confirm unilateral ectasia, potentially characterizing the inherent ectasia susceptibility of the cornea, which should be the subject of future studies.Dr. Ambrosio, Dr. P. Vinciguerra, and Dr. Roberts are consultants for, Dr. Buhren has received lecture fees from, and Dr. Elsheikh has received research funding from Oculus Optikgerate GmbH (Wetzlar, Germany). The remaining authors have no financial or proprietary interest in the materials presented herein.info:eu-repo/semantics/publishedVersio

Optical imaging and the impact of Rosiglitazone treatment on wound healing in the cat cornea.

<p>Illustrative confocal images were taken 15 µm below the basal epithelial layer of the central cornea in one eye treated with DMSO/Celluvisc vehicle solution (<b>A, C, E</b>), and one eye treated with 10 µM Rosiglitazone (<b>B, D, F</b>) daily for 2 weeks after laser ablation. Pre-operative images (<b>A, B</b>) show a quiescent stroma that appears quite similar across the two eyes. Two weeks after laser ablation, just after the end of topical treatments, both corneas showed increased reflectivity, which was highest in the vehicle-treated eye (<b>C</b>) and least in the Rosiglitazone-treated eye (<b>D</b>). By 12 weeks post-operatively, the Rosiglitazone-treated eye’s reflectivity was back down to basal levels (<b>F</b>), while the vehicle-treated eye remained hazier than pre-operatively (<b>E</b>). OCT images of a Rosiglitazone-treated eye collected pre-operatively (<b>G</b>), 4 weeks (<b>H</b>) and 12 weeks (<b>I</b>) post-operatively illustrate a bright zone of reflectivity at 4 weeks post-op, which was not present pre-operatively and is lost by 12 weeks post-op. <b>J</b>. Plot of normalized intensity change in the anterior 30% of the stroma relative to pre-operative values (dotted line at zero), measured from OCT images such as those in G–I. <b>K</b>. Similar plot of normalized pixel intensity change against post-operative time for the posterior 30% of the stroma in either untreated, vehicle-treated or Rosiglitazone-treated cat corneas post-excimer laser ablation. Error bars = SEM. N = number of eyes, which differs at different time-points (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070785#pone-0070785-t001" target="_blank">Table 1</a>). DMSO/Cell = DMSO/Celluvisc treated eyes. Cell = Celluvisc treated eyes.</p

Change in higher order wavefront aberration root mean square (RMS) 2 and 12 weeks after laser ablation relative to pre-operative levels.

<p><b>A.</b> Plot of change in higher order RMS (HORMS) at 2 and 12 weeks post-laser ablation in Rosiglitazone-, DMSO/Celluvisc and Celluvisc -treated cat eyes. HORMS increased significantly relative to pre-operative levels in all groups of eyes, and this elevation was maintained all the way out to 12 weeks post-PRK, but there were no significant inter-group differences in the magnitude of the change, whose significance was likely driven predominantly by spherical aberration (SA). <b>B.</b> Plot of change in residual HORMS illustrating significantly smaller increases in Rosiglitazone-treated eyes relative to both vehicle-treated eyes. These differences are maintained out to 12 weeks post-operatively. <b>C.</b> In contrast, the magnitude of increase in coma RMS is not significantly different between treatment groups, at either 2 or 12 weeks post-PRK. <b>D.</b> Finally, spherical aberration (SA) RMS does not appear significantly increased 2 weeks post-laser ablation in Rosiglitazone or DMSO/Celluvisc-treated eyes, but all 3 groups show a similar, positive change in SA RMS relative to pre-operative values by 12 weeks post-PRK. Error bars = SEM, N = number of eyes, * p<0.05, Student’s t-test.</p