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Acute central retinal artery occlusion (CRAO) induces a time-dependent increase in retinal thickness. By manually measuring the relative retinal thickness increase (RRTI) in comparison to the contralateral eye based on optical coherence tomography (OCT), ischemia onset within the past 4.5 hours could be determined with 100% sensitivity and 94.3% specificity. To enable examiner-independent and quicker diagnostics, we analyzed the RRTI using the automatic retinal thickness measurement. In this retrospective study, 28 eyes were evaluated with an acute CRAO (

There are many disease patterns that are treated jointly by neurologists and ophthalmologists, for which optical coherence tomography (OCT) is of important differential diagnostic significance. In this context neurologists are mainly confronted by two patient collectives: patients with an acute ischemic event, who present with an acute but painless monocular visual deterioration (for central retinal artery occlusion) or with a monocular visual field defect (for arterial branch occlusion or anterior ischemic optic neuropathy). The second collective is patients without ophthalmological symptoms but with conspicuous optic nerve findings (papilledema or optic disc drusen). In this overview article both patient collectives are considered separately. In addition, the most important OCT findings for optic neuritis are presented. Before the disease patterns are described in detail, the normal OCT findings and the diagnostic possibilities of OCT are explained.Es gibt viele Krankheitsbilder, die von Neurologen und Ophthalmologen gemeinsam behandelt werden, bei denen die optische Kohärenztomographie (OCT) von wichtiger differenzialdiagnostischer Bedeutung ist. Hierbei werden Neurologen hauptsächlich mit zwei Patientenkollektiven konfrontiert: zum einen Patienten mit einem akut ischämischen Geschehen, welche sich mit einer akuten, schmerzlosen monokularen Sehverschlechterung (bei Zentralarterienverschluss) bzw. mit einem monokularen Gesichtsfelddefekt (bei Arterienastverschluss oder anteriorer ischämischer Optikusneuropathie) präsentieren und zum anderen Patienten ohne ophthalmologische Symptomatik, aber mit auffälligen Sehnervenbefunden (Stauungspapille oder Drusenpapille). Diese beiden Patientenkollektive möchten wir in dieser Übersichtsarbeit getrennt voneinander betrachten. Zudem werden wir die wichtigsten OCT-Befunde bei der Optikusneuritis darstellen. Bevor die Krankheitsbilder im Detail beschrieben werden, sollen der OCT-Normalbefund sowie die diagnostischen Möglichkeiten der OCT erläutert werden.

Acute central retinal artery occlusion (CRAO) represents an ophthalmological emergency with neurological implications, which must be immediately investigated and treated. Intravenous thrombolysis could improve the prognosis only within the first 4.5 h due to limited retinal tolerance to ischemia. Accordingly, ophthalmological acute diagnostics should be reduced to the minimum necessary followed by immediate referral to a clinic with neurovascular expertise. The typical anamnesis is well-suited for triaging and should be carried out ín a standardized way in order to determine the onset of symptoms as exactly as possible. In addition to pathognomic findings in fundoscopy, there are characteristic ischemia-related changes in optical coherence tomography (OCT), which document ischemia in the inner retina and under some circumstances can provide inferences for the onset of ischemia.This review article summarizes the acute ophthalmological diagnostic management of acute CRAO with a focus on the typical OCT and transorbital ultrasound (TOUS) findings and discusses their potential use as ischemic biomarkers.Characteristic biomarkers make OCT an important diagnostic tool in the management of acute CRAO. Additional information can be obtained by TOUS. With an evidence-based treatment established in the future both tools could be used for indications for treatment and for estimating the prognosis.HINTERGRUND: Der akute Zentralarterienverschluss (ZAV) stellt einen ophthalmologischen Notfall mit neurovaskulären Implikationen dar, der sofort untersucht und behandelt werden sollte. Eine intravenöse Thrombolyse könnte aufgrund der begrenzten retinalen Ischämietoleranz nur innerhalb der ersten 4,5 h die Prognose verbessern. Die augenärztliche Akutdiagnostik sollte entsprechend auf das notwendige Minimum reduziert werden und eine unmittelbare Überweisung in eine Klinik mit neurovaskulärer Expertise erfolgen. Die typische Anamnese eignet sich gut zur schnellen Triagierung und sollte deshalb standardisiert durchgeführt werden, um insbesondere den Symptombeginn möglichst genau zu bestimmen. Neben pathognomonischen Befunden in der Fundoskopie bestehen typische Zeichen in der optischen Kohärenztomographie (OCT), die die Ischämie in der inneren Netzhaut dokumentieren und unter Umständen Rückschlüsse auf den Ischämiebeginn liefern. ZIEL: Diese Übersichtsarbeit erläutert die augenärztliche Akutdiagnostik des akuten retinalen ZAV mit dem Schwerpunkt auf typische Befunde der OCT und transorbitalen Sonographie (TOS) und diskutiert deren möglichen Nutzen als ischämische Biomarker.Charakteristische Biomarker machen die OCT zu einem wichtigen diagnostischen Instrument des akuten retinalen ZAV. Weitere Informationen können mittels TOS gewonnen werden. Bei einer in Zukunft etablierten evidenzbasierten Therapie könnten beide Mittel zur Indikationsstellung und Prognoseabschätzung hinzugezogen werden.

Purpose Acute central retinal artery occlusion (CRAO) induces ischaemic retinal oedema. The purpose of this study was to define sensitivity and specificity of optical coherence tomography (OCT) based retinal thickness analysis in determining ischaemia onset in CRAO. Methods The relative retinal thickness increase (RRTI) in comparison with the fellow eye was analysed retrospectively in OCT scans of 66 patients diagnosed with CRAO between January 2010 and December 2019 within 48 hr of ischaemia onset. The natural course of RRTI and the sensitivity and specificity of OCT-based determination of ischaemia onset in identifying CRAO within 4.5 hr using the RRTI were evaluated. Results Relative retinal thickness increase (RRTI) in acute CRAO follows a hyperbolic curve with a steep incline within the early phase after which it reaches a plateau. Optical coherence tomography (OCT)-based retinal thickness analysis in CRAO allows to differentiate patients with ischaemia onset within the past 4.5 hr or thereafter with a sensitivity of 100% and a specificity of 94.3%. Conclusion Relative retinal thickness increase (RRTI) allows to identify CRAO patients that are eligible for a potentially beneficial reperfusion therapy within a therapeutic window of 4.5 hr with a high accuracy. Especially in patients with unknown ischaemia onset, this diagnostic tool could be of major importance in the future clinical management.

Experimental research on corneal endothelial cells is associated with several difficulties. Human donor corneas are scarce and rarely available for experimental investigations as they are normally needed for transplantation. Endothelial cell cultures often do not translate well to in vivo situations. Due to the biostructural characteristics of non-human corneas, stromal swelling during cultivation induces substantial corneal endothelial cell loss, which makes it difficult to perform cultivation for an extended period of time. Deswelling agents such as dextran are used to counteract this response. However, they also cause significant endothelial cell loss. Therefore, an ex vivo organ culture model not requiring deswelling agents was established. Pig eyes from a local slaughterhouse were used to prepare split corneal buttons. After partial corneal trephination, the outer layers of the cornea (epithelium, bowman layer, parts of the stroma) were removed. This significantly reduces corneal endothelial cell loss induced by massive stromal swelling and Descemet's membrane folding throughout longer cultivation periods and improves general preservation of the endothelial cell layer. Subsequent complete corneal trephination was followed by the removal of the split corneal button from the remaining eye bulb and cultivation. Endothelial cell density was assessed at follow-up times of up to 15 days after preparation (i.e., days 1, 8, 15) using light microscopy. The preparation technique used allows a better preservation of the endothelial cell layer enabled by less stromal tissue swelling, which results in slow and linear decline rates in split corneal buttons comparable to human donor corneas. As this standardized organo-typically cultivated research model for the first time allows a stable cultivation for at least two weeks, it is a valuable alternative to human donor corneas for future investigations of various external factors with regards to their effects on the corneal endothelium.

Purpose Time is the key criterion in the management of non-arteritic central retinal artery occlusion (NA-CRAO). However, the precise onset of vision loss is often difficult to determine. This study aimed to evaluate the temporal changes of retinal thickness in acute NA-CRAO and the potential of this parameter to be used as a surrogate marker to estimate the onset of retinal ischaemia. Methods Optical coherence tomography was used to continuously assess retinal thickness and oedema progression rate in six porcine eyes. Additionally, a retrospective analysis of 12 patients with acute NA-CRAO was performed to determine association strength and progression rate between retinal thickness and onset of ischaemia. All Optical coherence tomography (OCT) scans (pigs and NA-CRAO patients) were performed within an ischaemic time frame of up to 9 hr. Results Retinal oedema progression rate in pigs was 25.32 µm/hr [CI 95%: 24.24-26.40 µm/hr]. Retrospective analysis of the patients revealed a strong correlation between retinal oedema and duration of ischaemia (Spearman's rho = 0.77, p = 0.004) with an estimated progression rate of 10.02 µm/hr [CI 95%: 3.30-16.74 µm/hr]. Conclusion Retinal thickness increases with oedema formation, and ischaemia onset is strongly correlated with this structural biomarker in both, pigs and NA-CRAO patients. Prospective clinical trials will have to determine the clinical feasibility of retinal thickness measurements as a biomarker to support clinical management of NA-CRAO.

PURPOSE The purpose of this study was to establish a standardized in vitro phacoemulsification damage model for future investigations of the effects of phacoemulsification, surgical devices, protective ophthalmic viscoelastic devices (OVDs), irrigation solutions and other aspects related to cataract phacoemulsification surgery on the corneal endothelium using porcine eyes. METHODS Thirty-four porcine eyes were randomly assigned to three groups (phacoemulsification (n = 13), irrigation (n = 9), control (n = 12)). A total of 5 min of ultrasound energy with intermittent irrigation/aspiration was applied in the eyes of the phacoemulsification group. The eyes of the irrigation group received the identical treatment, but without the application of ultrasound energy. The control group was left untreated. All eyes were then prepared to split corneal buttons followed by 15 days of cultivation. Endothelial cell density (ECD) was assessed blinded on day 15. RESULTS Endothelial cell density declined significantly more until day 15 in the phacoemulsification group (2567 ± 317/267 cells/mm² (median ± 25%/75%-quartiles), -32.5 ± 7.0/6.4%) compared to the irrigation (3450 ± 350/383 cells/mm², -11.8 ± 5.3/2.6%; p

Purpose: To evaluate the effects of perfluorobutylpentane (F4H5) on corneal endothelial cell density (ECD) and morphology using a porcine corneal endothelial organ culture model.Materials and metho...

To determine the corneal endothelial cell density human donor corneas are usually placed in hypotonic balanced salt solution for unstained cell counting. Experimental studies often stain the corneal endothelium to highlight cells and cell borders and simplify counting. However, staining normally terminates the experiments. Up to date, there is no publication comparing endothelial cell counts before and after staining. This study compared the counting results of unstained (hypotonic balanced salt solution) and stained (trypan blue & alizarin red S) assessment of the corneal endothelial cell density. No evidence for significantly differing cell counts was found between unstained and stained analysis of the corneal endothelial cell density. Therefore, we consider unstained counting non-inferior to stained counting.

Human corneas usually are not available for research, as they are used for transplantation only. At the same time, scientific studies on cultured human endothelial cells can produce misleading results due to inevitable dedifferentiation. Therefore, an organ-culture model of porcine corneas—displaying endothelial cell death rates comparable to those of cultured human corneas—would be very desirable. Fresh pig eyes were prepared under sterile conditions to obtain corneoscleral buttons, corneal buttons and so called “split corneal buttons” (new preparation method) and cultivated for 15 days. Morphology of the endothelial cell layer was observed by light microscopy on day 1, 8 and 15. On day 15 staining with trypan blue and alizarin red S was performed. Photographs were evaluated in a randomized, blinded manner. Here, the morphology of the corneal endothelium and the number of endothelial cells per mm2 were analyzed. After 15 days of cultivation the endothelial cell layer was maintained only in corneal buttons and split corneal buttons. Alizarin red S stained areas and the existence of polymorphisms like rosette figures and reformation figures were significantly less frequent in split corneal buttons than in corneal buttons. Loss of endothelial cells was significantly greater in corneal buttons [575 ± 25/250 cells/mm2 (median ± 25%/75%-quantile); 14.8%] than in split corneal buttons [417 ± 138/179 cells/mm2 (median ± 25%/75%-quantile); 10.2%]. The new preparation method of split corneal buttons allows the cultivation of porcine corneas for 2 weeks with cell death rates comparable to those of the corresponding human tissue in cornea banks without the need to add de-swelling additives to the media. This is therefore a simple and highly reliable method model to be applied in intervention studies on corneal endothelial cells in their natural compound.