Funktionelle Magnetresonanztomographie zur Darstellung zerebraler Aktivierungen bei thermischen Schmerzreizen ohne Medikation sowie nach Gabe von Remifentanil und Metamizol

Ziel. Thema der vorliegenden Arbeit ist die Untersuchung der zerebralen Schmerzverarbeitung. Mit der Methode der funktionellen Magnetresonanztomographie sollten Kortexareale lokalisiert werden, die bei thermischer Schmerzreizung am linken Vorfuß eine Aktivitätszunahme zeigen. Ziel war es, diese unter standardisierten Bedingungen reproduzierbar nachzuweisen und damit die Voraussetzung zu schaffen, Veränderungen dieser Aktivierungen bei Sauerstoff- und Analgetikagabe zu erfassen. Methodik. Zunächst wurden die physikalischen Grundlagen der Bilderzeugung mittels Magnetresonanztomographie vorgestellt. Dabei wurde insbesondere auf die funktionelle Bildgebung und die zugrunde liegende Physiologie eingegangen. Im speziellen Methodikteil wurden das untersuchte Kollektiv (6 gesunde Probanden) und der Versuchsablauf beschrieben. An einem 1,5 Tesla Magnetresonanztomographen wurden mit Hilfe von T2*-gewichteten Sequenzen funktionelle Bilddaten der Probandengehirne bei schmerzhafter und neutraler thermischer Stimulation am linken Fußrücken aufgezeichnet. An vier der Probanden wurden diese Messungen jeweils viermal wiederholt, um schmerzspezifische zerebrale Aktivierungen zu erfassen und deren intra- und interindividuelle Variabilität zu überprüfen. Im Anschluss wurden diese funktionellen Messungen an allen Probanden ohne und mit Gabe von Sauerstoff durchgeführt, um einen denkbaren negativen Effekt der bei Analgetikagabe erforderlichen Sauerstoffapplikation auf die Darstellung der zerebralen Aktivierungen auszuschließen. Damit waren die Voraussetzungen geschaffen, die Auswirkungen von Schmerzmedikamenten auf die zerebrale Aktivität bei Schmerzreizen zu untersuchen. In einem Pilotversuch wurde die beschriebene Messmethodik bei drei Probanden unter Gabe von Remifentanil, Metamizol und Kochsalzlösung in randomisierter Abfolge eingesetzt. Die Auswertung der funktionellen Bilddaten erfolgte anhand des General Linear Model (Softwarepaket FSL). Hiermit konnten sowohl individuelle zerebrale Aktivierungen erfasst, als auch Gruppenanalysen durchgeführt werden. Ergebnisse. Bei den Experimenten zur Lokalisation der zerebralen Aktivierungen konnten bei schmerzhafter Stimulation aktivierte Areale am häufigsten im frontalen Operculum und benachbarten Inselkortex, im dorsolateralen präfrontalen Kortex, im Gyrus frontalis medius, im anterioren Cingulum und im parietalen Operculum/SII Kortex nachgewiesen werden. Weniger häufig konnten Aktivierungen im primären somatosensorischen Kortex, im Thalamus, im Temporallappen, in den Basalganglien und im Hirnstamm nachgewiesen werden. Diese waren meist beidseits vorhanden, zeigten jedoch eine Betonung der kontralateral zur stimulierten Körperhälfte gelegenen Hirnhemisphäre. Im Vergleich mit der Neutralmessung stellten sich die aktivierten Areale im frontalen Operculum und der vorderen Inselregion, im anterioren Cingulum und in den Basalganglien als schmerzspezifisch dar. Die Aktivierungen im parietalen Operculum/SII Kortex konnten erst bei niedrigerem Signifikanzniveau nachgewiesen werden. Der interindividuelle Vergleich zeigte bei zwei der Probanden eine gute Übereinstimmung mit den zerebralen Aktivierungen der Gesamtgruppe. Zwei weitere Probanden wiesen jedoch ein deutlich unterschiedliches Aktivierungsmuster auf. Bei der intraindividuellen Analyse zeigte sich eine gute Reproduzierbarkeit der aktivierten Areale. Bei den Experimenten mit Sauerstoffgabe konnte ein negativer Effekt auf die Darstellung der zerebralen Aktivierungen ausgeschlossen werden. Bei Gabe von Remifentanil konnte der aus der klinischen Erfahrung bekannte ausgeprägte analgetische Effekt der Substanz beobachtet werden. In der funktionellen MRT ließen sich nach Gabe von Remifentanil keine zerebralen schmerzspezifischen Aktivierungen darstellen. Allerdings ergaben Kontrollmessungen bei visueller Stimulation ebenfalls eine Abnahme der zerebralen Aktivierungen. Bei Gabe von Metamizol konnte unter den gewählten Versuchsbedingungen kein analgetischer Effekt registriert werden. Als Erklärung kommt einerseits die niedrig gewählte Dosierung, andererseits die Pharmakokinetik der Substanz in Betracht. Eine Änderung des zerebralen Aktivierungsmusters konnte bei den drei untersuchten Probanden nicht objektiviert werden. Schlussfolgerung. Mit der funktionellen Magnetresonanztomographie war es möglich, durch Schmerzreize ausgelöste zerebrale Aktivierungen darzustellen. Diese Daten können als Grundlage für weitere Experimente mit schmerzmodulierenden Medikamenten dienen. Die gewählten Rahmenbedingungen der fMRT-Messungen gewährleisten die notwendige Sicherheit der Probanden während der Applikation von Schmerzmedikamenten, ohne die Darstellbarkeit der zerebralen Aktivierungen zu beeinträchtigen. Aussagen über die Wirkung von opioidartigen und nichtopioidartigen Analgetika müssen jedoch noch an einer größeren Gruppe von Probanden evaluiert werden

Selective retina therapy (SRT) in patients with geographic atrophy due to age-related macular degeneration

For geographic atrophy (GA) due to age-related macular degeneration (AMD) there is so far no approved treatment option. Usually, increased autofluorescence (AF) levels of different patterns adjacent to the atrophic area indicate lipofuscin-laden retinal pigment epithelium (RPE) cells at a high risk for apoptosis. Herein, SRT was used to selectively treat these cells to stimulate RPE proliferation, in order to reduce or ideally stop further growth of the atrophic area

Selective Retina Therapy in Acute and Chronic-Recurrent Central Serous Chorioretinopathy

Purpose: Selective retina therapy (SRT), the confined laser heating and destruction of retinal pigment epithelial cells, has been shown to treat acute types of central serous chorioretinopathy (CSC) successfully without damaging the photoreceptors and thus avoiding laser-induced scotoma. However, a benefit of laser treatment for chronic forms of CSC is questionable. In this study, the efficacy of SRT by means of the previously used 1.7-µs and shorter 300-ns pulse duration was evaluated for both types of CSC, also considering re-treatment for nonresponders. Material and Methods: In a two-center trial, 26 patients were treated with SRT for acute (n = 10) and chronic-recurrent CSC (n = 16). All patients presented with subretinal fluid (SRF) in OCT and leakage in fluorescein angiography (FA). SRT was performed using a prototype SRT laser system (frequency-doubled Q-switched Nd:YLF-laser, wavelength 527 nm) with adjustable pulse duration. The following irradiation settings were used: a train of 30 laser pulses with a repetition rate of 100 Hz and pulse durations of 300 ns and 1.7 µs, pulse energy 120-200 µJ, retinal spot size 200 µm. Because SRT lesions are invisible, FA was always performed 1 h after treatment to demonstrate laser outcome (5-8 single spots in the area of leakage). In cases where energy was too low, as indicated by missing FA leakage, energy was adjusted and the patient re-treated immediately. Observation intervals were after 4 weeks and 3 months. In case of nonimprovement of the disease after 3 months, re-treatment was considered. Results: Of 10 patients with active CSC that presents focal leakage in FA, 5 had completely resolved fluid after 4 weeks and all 10 after 3 months. Mean visual acuity increased from 76.6 ETDRS letters to 85.0 ETDRS letters 3 months after SRT. Chronic-recurrent CSC was characterized by less severe SRF at baseline in OCT and weaker leakage in FA than in acute types. Visual acuity changed from baseline 71.6 to 72.8 ETDRS letters after 3 months. At this time, SRF was absent in 3 out of 16 patients (19%), FA leakage had come to a complete stop in 6 out of 16 patients (38%). In 6 of the remaining chronic CSC patients, repeated SRT with higher pulse energy was considered because of persistent leakage activity. After the re-treatment, SRF resolved completely in 5 patients (83.3%) after only 25 days. Conclusion: SRT showed promising results in treating acute CSC, but was less effective in chronic cases. Interestingly, re-treatment resulted in enhanced fluid resolution and dry conditions after a considerably shorter time in most patients. Therefore, SRT including re-treatment if necessary might be a valuable CSC treatment alternative even in chronic-recurrent cases

Subretinale Lufteingabe zur Behandlung postoperativer Netzhautfalten nach Ablatio

Hintergrund Faltenbildungen der Netzhaut stellen ein Problem v. a. nach Vitrektomie oder Buckelchirurgie mit Gaseingabe dar. Liegen diese Falten im Makulabereich, wirkt sich das meist erheblich auf das Sehvermögen des Patienten aus. Im Folgenden wird eine Behandlungstechnik solcher Falten beschrieben. Methode In einem Zeitraum von Januar 2017 bis Juni 2020 wurden 6 Patienten mit der im Folgenden beschriebenen Behandlungstechnik operiert. Es erfolgte die erneute Abhebung der Netzhaut mittels Balanced Salt Solution (BSS), gefolgt von einer subretinalen Eingabe gefilterter Luft. Das Ausstreichen der Falte erfolgte mithilfe von Perfluorcarbon (PFC). Eine postoperative Drainage der subretinalen Luft und Flüssigkeit erfolgte nicht, die Spontanresorption wurde abgewartet. Ergebnisse Bei keinem Patienten kam es zu einer Visusverschlechterung nach erneuter Netzhautabhebung. Eine Verbesserung der Sehschärfe zeigte sich bei 4 von 6 Fällen. Eine Verminderung der Metamorphopsien konnte bei 5 von 6 Patienten erreicht werden, 2 Patienten gaben an, die Metamorphopsien gar nicht mehr wahrzunehmen. Nur 1 Patient berichtete über einen gleichbleibend verzerrten Seheindruck trotz anatomisch glatter zentraler Netzhaut. Schlussfolgerung Bei kritischer Indikationsstellung stellt unsere Behandlungstechnik eine sichere und erfolgreiche Vorgehensweise zur Behandlung von Netzhautfalten im Bereich der Makula nach Ablatiooperation dar

Pseudophakes zystoides Makulaödem

Pseudophakic cystoid macular edema (PCME) is still one of the most frequent causes of loss of vision after cataract surgery. Clinical PCME occurs after initial improvement of vision 2-10 weeks after surgery in 1-2% with secondary vision loss and biomicroscopically visible macular cysts. Alterations, which are often not associated with functional limitations, can frequently be seen with angiography and optical coherence tomography (OCT). Inflammation mediators are released due to the surgical trauma in the anterior segment of the eye and diffuse to the capillaries of the macula where they lead to exudation of fluid into the retinal tissue and swelling of the macula. Risk factors for PCME are complicated cataract surgery, diabetes, uveitis, epiretinal gliosis and a status after retinal vein occlusion. In eyes at risk, perioperative prophylaxis with topical nonsteroidal anti-inflammatory drugs should be prescribed. The natural course of PCME is often benign with spontaneous recovery over several months; however, to avoid irreversible loss of vision treatment should be initiated

Corneal Endothelial Cell Loss in Femtosecond Laser-assisted Descemetʼs Stripping Automated Endothelial Keratoplasty

Background: Descemet's stripping automated endothelial keratoplasty (DSAEK) surgery offers a more standardized approach and reliable method to create corneal grafts with an instrument such as a microkeratome. With the development of Descemet's membrane endothelial keratoplasty, an excellent clinical outcome is seen in the treatment of corneal endothelial dysfunctions, which indicates that thinner corneal graft results in better clinical outcome. With the recent development of the femtosecond laser, ultrathin conical graft preparation has become possible. This study aimed to report corneal graft endothelial cell loss (ECL) in a large series of cases undergoing DSAEK with femtosecond laser-assisted corneal graft preparation within a 12-month period. Methods: This study was designed as a prospective, noncomparative, interventional case series. Totally 126 consecutive eyes with endothelial failure of 120 patients, who had corneal endothelial decompensation and underwent femtosecond-assisted DSAEK using the VisuMax femtosecond laser system, were included in the study. Central endothelial cell density (ECD) was recorded postoperatively at 2 weeks (n = 126), 1 month (n = 126), 3 months (n = 110), 6 months (n = 101), and 12 months (n = 71) and then compared with the preoperative eye bank measurements. Pre- and postoperative central ECDs were evaluated using Heidelberg retina tomography-III confocal microscopy. ECL was calculated for each postoperative time point. Graft thickness was examined using anterior segment-optical coherence tomography. Results: Mean preoperative cell count was 3383 350 cells/mm(2). Mean postoperative cell counts were 2382 707 cells/mm(2), 2179 685 cells/mm(2), 2074 688 cells/mm(2). 1884. 662 cells/mm(2), and 1723 624 cells/mm(2) at 2 weeks, 1, 3, 6. and 12 months, respectively; these represented the ECL of 29.7 +/- 19.7%, 35.4 +/- 19.5%, 38.6, 19.8%, 44.3 +/- 18.9%, and 48.9 +/- 18.4% at the each corresponding time point. The mean corneal graft thickness after surgery was 142 +/- 48 mu m, 118 +/- 41 mu m, 108 +/- 37 mu m, 100 +/- 32 mu m, and 99 +/- 32 mu m at each corresponding study visit, respectively. There was no correlation between corneal graft thickness and corneal ECL (R = 0.039). Conclusions: Corneal ECL remained relatively stable up to 12 months after femtosecond laser-assisted ultrathin DSAEK in a large case series. No correlation between cell loss and corneal graft thickness was found, which indicated that corneal graft preparation by the femtosecond laser was safe. ECL was faster within the first 6 months and relatively stable thereafter

Rhegmatogenous retinal detachment repair—does age, sex, and lens status make a difference?

Purpose To analyze the correlation between lens status, age, and sex in the epidemiology and success rates of rhegmatogenous retinal detachment (RRD) surgery. Methods The files of all consecutive patients undergoing vitreoretinal surgery for uncomplicated RRD between Jan 2005 und Dec 2020 were retrospectively reviewed. Successful outcome was defined as no retinal redetachment occurring within 3 months after surgery. Results 5502 eyes with uncomplicated primary RRD were included. Mean age of the patients was 61.1 years (± 13.6 SD). In the age group over 40 years, a male predominance was found. The percentage of pseudophakic RRD increased from 25 to 40% during the 15 years observation period. In the age group 50 to 69 years, patients with pseudophakic detachments were male in 786 out of 1079 cases (72.9%). In the same age group, 1285 of 2110 (60.9%) patients with phakic RRD were male. Overall, primary success rate after one procedure was 91.2% (5018 of 5502). In the phakic eyes, the primary success rate was higher in those eyes that underwent combined phacovitrectomy (93.0%), compared to those without simultaneous cataract surgery (88.7%; p = 0.002). Conclusion The ratio of male and female patients with RRD varies between age groups. The proportion of pseudophakic RRD has increased within 15 years. The male predominance in RRD is stronger in pseudophakic than in phakic eyes. In phakic eyes with RRD, a combined phacovitrectomy yielded better anatomical results

The learning curve of retinal detachment surgery

Purpose To investigate the learning curve of vitreoretinal (VR) surgeons beginning training in retinal detachment (RD) surgery. Methods The files of all consecutive patients undergoing VR surgery for uncomplicated RD between Jan 2005 und Mar 2020 were retrospectively reviewed. Successful outcome was defined as no retinal redetachment within 3 months after surgery. Results Ten surgeons started their VR career during this period. Together, these 10 surgeons performed 3786 RD operations (mean 379; median 251; range 71–1053). Primary success rate after one operation was 90% (3420 of 3786). When starting to operate retinal detachments, VR surgeons had a primary success rate of about 80%. Redetachment rates steadily decreased and stabilized at just under 10% after about 200 operations. Beginners needed more than twice the time for the procedure compared to experienced surgeons. The individual learning curves varied widely. In our series, female surgeons seem to have a faster learning curve. Conclusion RD surgery performed by VR surgeons in training had acceptable results. With increasing experience, success rates continuously improve reaching stable levels after approximately 200 operations. The training of VR surgeons requires considerable resources

Residual Iris Retraction Syndrome After Artificial Iris Implantation

PURPOSE: To evaluate the effect of an artificial iris implant on the remnant iris. DESIGN: Interventional case series. METHODS: SETTING: Single center. PATIENT POPULATION: Forty-two consecutive patients. Observation Procedures: Morphologic evaluation over 24 +/- 14 months. MAIN OUTCOME MEASURES: Remnant pupillary aperture, iris color, visual acuity, intraocular pressure, and endothelial cell count. RESULTS: In 7 of 42 cases (16.7%), the residual iris aperture dilated from 36.6 +/- 15.4 mm(2) preoperatively to 61.1 +/- 12.5 mm(2) 1 year postoperatively (66.9% increase). In 5 of 7 affected eyes the artificial iris had been implanted into the ciliary sulcus; in 2 eyes it had been sutured to the sclera. Four of the 7 patients presented with remarkable complications: 2 eyes needed glaucoma shunt surgeries owing to pigment dispersion; 1 suffered from recurrent bleedings; and in 1 case artificial iris explantation was performed owing to chronic inflammation. Anterior chamber depth and angle, endothelial cell count, and visual acuity did not change in this cohort. Changes in color were not observed in the remnant iris. CONCLUSIONS: The implantation of an artificial iris prosthesis can lead to a residual iris retraction syndrome. It is likely that residual iris is trapped in the fissure between the artificial iris and the anterior chamber angle, preventing further pupil constriction. Another possibility could be a constriction or atrophy of the residual iris. A scleral sutured implant and an implantation in the capsular bag were both found to prevent the iris retraction. The study group number is inadequate to allow statistical comparison of these different implantation methods. As the use of artificial irises increases, we may expect more patients with iris retraction syndrome in the future. (C) 2018 Elsevier Inc. All rights reserved

OCT-based deep learning algorithm for the evaluation of treatment indication with anti-vascular endothelial growth factor medications

Intravitreal injections with anti-vascular endothelial growth factor (anti-VEGF) medications have become the standard of care for their respective indications. Optical coherence tomography (OCT) scans of the central retina provide detailed anatomical data and are widely used by clinicians in the decision-making process of anti-VEGF indication. In recent years, significant progress has been made in artificial intelligence and computer vision research. We trained a deep convolutional artificial neural network to predict treatment indication based on central retinal OCT scans without human intervention. A total of 183,402 retinal OCT B-scans acquired between 2008 and 2016 were exported from the institutional image archive of a university hospital. OCT images were cross-referenced with the electronic institutional intravitreal injection records. OCT images with a following intravitreal injection during the first 21 days after image acquisition were assigned into the 'injection' group, while the same amount of random OCT images without intravitreal injections was labeled as 'no injection'. After image preprocessing, OCT images were split in a 9:1 ratio to training and test datasets. We trained a GoogLeNet inception deep convolutional neural network and assessed its performance on the validation dataset. We calculated prediction accuracy, sensitivity, specificity, and receiver operating characteristics. The deep convolutional neural network was successfully trained on the extracted clinical data. The trained neural network classifier reached a prediction accuracy of 95.5% on the images in the validation dataset. For single retinal B-scans in the validation dataset, a sensitivity of 90.1% and a specificity of 96.2% were achieved. The area under the receiver operating characteristic curve was 0.968 on a per B-scan image basis, and 0.988 by averaging over six B-scans per examination on the validation dataset. Deep artificial neural networks show impressive performance on classification of retinal OCT scans. After training on historical clinical data, machine learning methods can offer the clinician support in the decision-making process. Care should be taken not to mistake neural network output as treatment recommendation and to ensure a final thorough evaluation by the treating physician