Vorhersagemodell für die Dezentrierung und Verkippung von Intraokularlinsen

Hintergrund: Besonders bei asphärischen oder multifokalen Kunstlinsen beeinträchtigen, Dezentrierung und Verkippung von Intraokularlinsen (IOL) die Abbildungsqualität des Auges. Das Ziel dieser Arbeit war es, ein Vorhersagemodell für die Verkippung und Dezentrierung der IOL auf der Basis der präoperativen Biometrie und Position der eigenen Linse abzuleiten. Patienten und Methoden: In dieser retrospektiven Pilotstudie wurden 80 Augen (Altersdurchschnitt der Patienten 67 ± 12 Jahre) nach einer komplikationslosen Katarakt-Operation eingeschlossen. Bei allen eingeschlossenen Patienten wurde eine einstückige asphärische HOYA-Kunstlinse (Vivinex iSert XY1) implantiert. Präoperativ wurde die Biometrie (Achsenlänge, Vorderkammertiefe, Mittelwert der Keratometerwerte und Zylinder) mittels IOL-Master 500, sowie die mittels Vorderaugenabschnitts-OCT (CASIA 2) gemessene Position der eigenen Linse (Dezentrierung und Verkippung) erfasst. Im Mittel 31 ± 6,1 Tage postoperativ wurde die Position der Kunstlinse (Dezentrierung und Verkippung) mit dem CASIA 2 erneut gemessen. Für die Definition der Vorhersage wurde eine automatische lineare Modellierung im Sinne eines Regressionsansatzes verwendet (Zielgrößen: IOL-Dezentrierung und -Verkippung, Prädiktoren: Biometriedaten und präoperative Position der eigenen Linse). Ergebnisse: Die Achsenlänge, Vorderkammertiefe, Mittelwert der Keratometerwerte und Zylinder in der präoperativen Biometrie wurden im Mittel mit 23,6 ± 1,1 mm / 3,0 ± 0,3 mm / 43,0 ± 1,4 Dioptrien / 0,7 ± 1,4 Dioptrien gemessen. Die Dezentrierung bzw. Verkippung der eigenen Linse lag präoperativ im Mittel bei 0,2 ± 0,1 mm (0,0 - 0,5) bzw. 5,7 ± 1,5° (1,0 ± 9,1°). Die Dezentrierung bzw. Verkippung der IOL lag postoperativ im Mittel bei 0,2 ± 0,1 mm (0,0 - 1,0) bzw. 5,8 ± 1,5° (1,2 ± 9,2°). Die Dezentrierung der IOL konnte am besten durch den präoperativen AL und DM - mit einem Bestimmtheitsmaß nicht besser als 13,5% - beschrieben werden. Die Verkippung der IOL konnte durch die präoperative Linsenverkippung - mit einem Bestimmtheitsmaß von 53,4% - beschrieben werden. Des Weiteren zeigt die eigene Linse sowohl eine vermehrte kaudale und temporale Dezentrierung entlang der y-Achse und x-Achse sowie außerdem, eine Verkippung des kaudalen und nasalen Teiles der eigenen Linse nach vorne (Richtung Iris). Schlussfolgerungen: Auf der Basis der präoperativen Biometriedaten lässt sich die Verkippung mit einem Bestimmtheitsmaß von 53,4% deutlich besser modellieren als die Dezentrierung. Dieses Modell wird in Zukunft mit einer erheblich größeren Stichprobe und für unterschiedliche IOL validiert und weiter verbessert

Structural changes in the corneal subbasal nerve plexus in keratoconus

Background Corneal confocal microscopy (CCM) allows visualizing slightest alterations within the corneal subbasal nerve plexus (SNP). Recent CCM studies based on the analysis of three–five CCM images per eye assumed a reduced corneal nerve fibre length (CNFL) in keratoconus (KC). Methods The SNP of KC patients (n = 23, 13 contact lens wearing, 10 noncontact lens wearing) and patients without KC (n = 16) was examined by 10 CCM images of one eye per patient. The CNFL per frame area was calculated, and the SNP tortuosity was quantified by measuring (a) the amplitude of the curves and (b) the area under the curve (AUC) formed by the SNP. Results Analysing 390 non‐overlapping confocal images revealed the CNFL (mm/mm2) to be significantly lower in KC (16.4 ± 1.9 mm/mm2) than in healthy corneae (23.8 ± 3.3 mm/mm2, p < 0.0001; mean ± SD; p‐value calculated using the Mann–Whitney U‐test), without a difference between contact lens wearing and noncontact lens wearing KC patients (p = 0.4). Amplitudes and AUCs analysed as median with 25th and 75th percentile were significantly increased in KC (amplitude 33/23/41 µm and AUC 2839/1545/3444 µm2) compared to healthy corneae (amplitude 24/18/28 µm and AUC 1870/1193/2327 µm2, p < 0.0001). Conclusions Corneal confocal microscopy (CCM) visualizes slightest alterations within the SNP in KC including (a) a significantly lower CNFL and (b) an enhanced winding course of the SNP. The significantly lower CNFL observed in KC may support the hypothesis of a neurodegenerative aspect of the disease and might be a measure to be correlated with the severity and progression of the disease

Corneae from body donors in anatomy department: valuable use for clinical transplantation and experimental research

Background: Explanted corneae are highly needed for the surgical management of patients with severe corneal diseases. The aim of this study was to determine whether the body donors from the Institute of Anatomy are a suitable source of donor corneae. Methods: At the Institute of Anatomy at Saarland University Medical Center in Homburg, corneae are prelevated from body donors who had consented to the removal of tissues for transplantation purposes during their lifetime. Following the report of death, the LIONS Eye Bank is informed and the contraindications of corneal explantation are clarified. Obtaining a blood sample within 24 h postmortem is mandatory. Results: The Institute of Anatomy had 150 body donors in the time period from January 2018 to June 2019. Out of these, 68 (45.3%) were reported to the Eye Bank. The age of the donors (median 82 years (range: 57–96)) is not critical since the quality of the corneae depends on the number of endothelial cells (mean: 2109 ± 67 cells/mm2 (range: 511–2944 cells/mm2)). Contraindications were present in 19 (12.6%) cases. The corneae were extracted from 49 (32.7%) body donors. Out of these 98 corneae, 46 (46.9%) were successfully transplanted. Of all non-transplanted corneae, 6 (6.1%) were microbiologically contaminated, 10 (10.2%) had a positive serology, 22 (22.5%) had an endothelial cell count < 2000 cells/mm2 and 6 (6.1%) are at time of this analysis still in culture medium. The non-transplanted tissues were used for research. Conclusions: Explanted corneae from the Institute of Anatomy are a valuable option in obtaining grafts for corneal transplantation, which is why we are working toward on expanding cooperation with this department

Outcomes of Severe Fungal Keratitis Using in vivo Confocal Microscopy and Early Therapeutic Penetrating Keratoplasty

Purpose: The purpose of this study was to assess the impact of early diagnosis using in vivo confocal microscopy and early therapeutic penetrating keratoplasty (TPK) on the outcomes of severe cases of fungal keratitis. Methods: This retrospective single-center study included 38 patients (40 eyes) with fungal keratitis who presented between December 2013 and February 2020. Preoperative, intraoperative, and postoperative parameters were recorded to assess the role of early correct diagnosis and early surgical therapy on visual acuity outcome and enucleation rate during follow-up. Results: The mean patient age was 51 years (71% females). The initial external diagnosis was correct in 20 cases (50%). The mean time from symptom onset until admission to our department was 46.8 ± 68.0 (median 28.5) days. The mean time to correct diagnosis after admission to our department was 1 day with in vivo confocal microscopy (IVCM). IVCM was performed in 38 cases, of which 36 (sensitivity: 94.7%) were positive for fungal infection. Twenty-seven out of 40 (67.5%) eyes received a TPK 4.2 ± 3.9 days after admission, with a mean graft size of 8.9 ± 1.9 mm. Three eyes (7.5%) were enucleated. The corrected distance visual acuity of the entire study population increased from 2.0 ± 1.2 LogMAR to 0.96 ± 1.17 LogMAR. Conclusion: In vivo confocal microscopy is a powerful tool for the early detection of fungal organisms in infectious keratitis. An early TPK with a large graft helps to eradicate the infection timely and results in a favorable visual acuity outcome and lower enucleation rate, especially when treating filamentous fungi

Imaging the Cornea, Anterior Chamber, and Lens in Corneal and Refractive Surgery

Anterior segment OCT (AS-OCT) is an optical and noncontact imaging technology, which has numerous fields of application in the imaging of the cornea, anterior chamber, and the lens. In this chapter, we will present some of the application fields of AS-OCT in corneal, cataract, and refractive surgery. We will emphasize the potential of AS-OCT by several clinical examples including corneal imaging (keratoconus, keratoplasty, and refractive surgery) and intraocular lens imaging after refractive surgery. AS-OCT shows special potential for corneal imaging in case of corneal edema and for postoperative control after Descemet’s membrane endothelial keratoplasty (DMEK). The postoperative follow-up of a posterior chamber Collamer lens’ses vault and measuring the anterior chamber angle could be identified as another promising field of application for AS-OCT

Assessing the Learning Curve for DMEK Using Post-Procedural Clinical Outcomes : Comparison of Four Different Surgeons during Two Different Periods

Purpose: Evaluating the learning curve of individual surgeons for Descemet Membrane Endothelial Keratoplasty (DMEK) and Triple-DMEK and assessing outcome with experience. Methods: The first 41 and the last 41 surgeries of each of the four surgeons were retrospectively included. Surgery duration and graft preparation time were recorded. Corrected distance visual acuity (CDVA, logMAR) and central corneal thickness (CCT, µm) were collected preoperatively after 6 and 12 months, as well as postoperative complications, e.g., re-bubbling or repeat penetrating keratoplasty. Results: Surgical duration for Triple-DMEK and DMEK decreased significantly by 21 min and 14 min between the two periods (p < 0.001; p < 0.001). Graft preparation time decreased significantly from 13.3 ± 5.2 min (95%CI 12.8–14.3) in period 1 to 10.7 ± 4.8 min (95%CI 10.2–11.4) in period 2 (p = 0.002). The postoperative changes in CDVA and CCT over both periods were not significant (p = 0.900; p = 0.263). The re-bubbling rate decreased significantly from 51.2% in period 1 to 26.2% in period 2 (p < 0.001). The repeat penetrating keratoplasty (PKP) was 7.3% in period 1 and 3.7% in period 2 (p = 0.146). Re-DMEK was necessary in 6.1% in period 1 and 4.9% in period 2 (p = 0.535). Several parameters showed significant differences between the surgeons in both periods (surgical duration: period 1: p < 0.001, period 2 p < 0.001; graft preparation: period 1: p < 0.001, period 2 p < 0.001). Conclusion: Significant decrease in surgery duration, graft preparation time, and the re-bubbling rate can be attributed to gained individual experience

Prevalence and severity of cornea guttata in the graft following Descemet Membrane Endothelial Keratoplasty (DMEK)

Purpose: The aim of this study was to determine the prevalence and severity of cornea guttata (CG) in grafts after Descemet membrane endothelial keratoplasty (DMEK) and to investigate its impact on various clinical parameters during follow-up. Methods: This retrospective study included 664 operations (DMEK and tripleDMEK) on 466 patients. The prevalence and progression of CG after the operation were examined using endothelial specular microscopy images. The severity grade of CG was classified into four grades: G0 without CG, G1 – G3 with increasing severity of CG. Clinical parameters such as central corneal thickness (CCT), visual acuity (VA), endothelial cell density (ECD), pleomorphism and polymegalism were examined during a postoperative follow-up time of 19.6 15.8 months. Results: Cornea guttata (CG) appeared postoperatively in 124 (18.7%) eyes. 112 (16.9%) could be classified as G1, 9 (1.4%) as G2 and only 3 (0.5%) as G3. The examination of clinical parameters showed significant differences between healthy and low-grade CG (G0/G1) and high-grade CG (G2/G3). A significant deterioration was found in the corrected distance visual acuity (CDVA) (p = 0.02). CCT showed an increase between G0 (534 58 lm) and G2 (549 71 lm)/G3 (558 56 lm) with a p-value of 0.02. Additionally, a significant increase in pleomorphism (p = 0.003) and polymegalism (p = 0.04) was detected. Conclusion: Cornea guttata (CG) prevalence after DMEK and triple-DMEK was found to be 18.7%, although most of these cases were classified as low-grade CG and showed no clinical significance. Around 1.9% were classified as high-grade CG and significantly affected several clinical parameters during the follow-up

Morphological characterization and clinical effects of stromal alterations after intracorneal ring segment implantation in keratoconus

Purpose To analyze the histological and (ultra)structural stromal tissue changes after femtosecond (Fs) laser–assisted intra corneal ring segment (ICRS) implantation and their refractive and topographic efects in patients with keratoconus. Methods This monocentric retrospective case series included 15 consecutive patients with clinical peri-segmental lamellar channel deposits after treatment with Fs-ICRS implantation for keratoconus. The stromal changes were investigated using in vivo confocal microscopy. Two patients underwent a penetrating keratoplasty after the Fs-ICRS implantation; the explanted corneas were processed for histopathology and transmission electron microscopy (TEM). Refractive and topographic efects were investigated comparing the uncorrected (UDVA) and corrected (CDVA) distance visual acuity, spherical equivalent (SE), fat (K1), steep (K2), and steepest (Kmax) keratometry before and after detection of lamellar channel deposits. Results In vivo confocal microscopy revealed difuse linear and focal granular hyperrefective structures. Histologically, there was mild proliferation of fbroblasts and fbrosis. TEM demonstrated focal accumulations of degenerated keratocytes with cytoplasmic lipid inclusions. There were no signifcant changes for UDVA (Δ=0.0±0.2 logMAR; p=0.67), CDVA (Δ=0.0±0.1 logMAR; p=0.32), SE (Δ 0.1±0.9 D; p=0.22), K1 (Δ=0.3±1.0 D; p=0.28), K2 (Δ=0.1±0.9 D; p=0.51), and Kmax (Δ=0.3±1.5 D; p=0.17). Conclusions Two types of structural stromal changes were identifed: (1) difuse peri-segmental fbrosis and (2) lamellar channel deposits. These structural changes showed no evidence of a relevant refractive or topographic efect

Reliability analysis of successive Corneal Visualization Scheimpflug Technology measurements in different keratoconus stages

ABSTRACT. Background: This study assesses the reliability of successive corneal biomechanical response measurements by the Corneal Visualization Scheimpflug Technology (CST, Corvis ST , Oculus Optikger€ate, Wetzlar, Germany) in different keratoconus (KC) stages. Methods: A total of 173 eyes (15 controls: 15 eyes, and 112 KC patients: stages 1|1–2|2|2–3|3|3–4|4, n = 26|16|36|18|31|26|5 according to Topographical KC Classification, TKC) were repeatedly examined five times with the CST, each after repositioning the patient’s head and re-adjusting the device. Tomographical analysis (Pentacam HR ; Oculus, Wetzlar, Germany) was performed once before and once after CST measurements. Outcome measures included (1) A1 velocity, (2) deformation amplitude (DA) ratio 2 mm, (3) integrated radius, (4) stiffness parameter A1 and (5) Ambrosio relational thickness to the horizontal profile (ARTh). The Corvis Biomechanical Index (CBI) is reported to be extracted out of these parameters. Mean values of the five measurements and Cronbach’s a were calculated as a measure for reliability. Results: Ambrosio relational thickness to the horizontal profile and SPA1 were significantly higher in controls (534|123) compared to TKC1 (384|88), TKC2 (232|66), TKC3 (152|55) and TKC4 (71|27; p < 0.0001). The other parameters were similar in controls and TKC1 (A1 velocity: 0.148|0.151 m/s; integrated radius: 8.2|8.6 mm 1 ), but significantly higher in TKC stages 2 to 4 (DA ratio 2 mm: 5.5|6.3|8.0; A1 velocity: 0.173|0.174|0.186 m/second; integrated radius: 10.9|12.8|19.0 mm 1 ; p < 0.0001). All parameters proved to be highly reliable (Cronbach’s a ≥ 0.834) and the corneal tomography remained unaffected. Conclusions: The individual parameters included in the CBI (consisting of ARTh, SPA1, DA ratio 2 mm, A1 velocity and integrated radius) are highly reliable but differ KC stage-dependently

Reliability and efficiency of corneal thickness measurements using sterile donor tomography in the eye bank

To evaluate the reliability and efficiency of sterile pachymetric measurements of donor corneas based on tomographic data using two different methods: a “manual” and a “(semi-)automated” method. Twenty-five (25) donor corneas (50%) stored in MI and 25 (50%) in MII were imaged 5 times consecutively using an anterior segment OCT (AS-OCT). The central corneal thickness (CCT) was measured both with the manual measurement tool of the AS-OCT (= CCTm) and with a MATLAB self-programmed software allowing (semi-)automated analysis (= CCTa). We analyzed the reliability of CCTm and CCTa using Cronbach´s alpha (α) and Wilcoxon signed-Rank Test. Concerning CCTm, 68 measurements (54.4%) in MI and 46 (36.8%) in MII presented distortions in the imaged 3D-volumes and were discarded. Concerning CCTa, 5 (4%) in MI and 1 (0.8%) in MII were not analyzable. The mean (± SD) CCTm was 1129 ± 6.8 in MI and 820 ± 5.1 µm in MII. The mean CCTa was 1149 ± 2.7 and 811 ± 2.4 µm, respectively. Both methods showed a high reliability with a Cronbach´s α for CCTm of 1.0 (MI/MII) and for CCTa of 0.99 (MI) and 1.0 (MII). Nevertheless, the mean SD of the 5 measurements was significantly higher for CCTm compared to CCTa in MI (p = 0.03), but not in MII (p = 0.92). Sterile donor tomography proves to be highly reliable for assessment of CCT with both methods. However, due to frequent distortions regarding the manual method, the (semi-)automated method is more efficient and should be preferred