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Background/aimsTo investigate the association of commonly used systemic medications with prevalent age-related macular degeneration (AMD) in the general population.MethodsWe included 38 694 adults from 14 population-based and hospital-based studies from the European Eye Epidemiology consortium. We examined associations between the use of systemic medications and any prevalent AMD as well as any late AMD using multivariable logistic regression modelling per study and pooled results using random effects meta-analysis.ResultsBetween studies, mean age ranged from 61.5±7.1 to 82.6±3.8 years and prevalence ranged from 12.1% to 64.5% and from 0.5% to 35.5% for any and late AMD, respectively. In the meta-analysis of fully adjusted multivariable models, lipid-lowering drugs (LLD) and antidiabetic drugs were associated with lower prevalent any AMD (OR 0.85, 95% CI=0.79 to 0.91 and OR 0.78, 95% CI=0.66 to 0.91). We found no association with late AMD or with any other medication.ConclusionOur study indicates a potential beneficial effect of LLD and antidiabetic drug use on prevalence of AMD across multiple European cohorts. Our findings support the importance of metabolic processes in the multifactorial aetiology of AMD.

Relative telomere length (RTL) is a biomarker for physiological aging. Premature shortening of telomeres is associated with oxidative stress, which is one possible pathway that might contribute to age-related macular degeneration (AMD). We therefore aimed to investigate the association between RTL and AMD in a well-characterized group of elderly individuals.We measured RTL in participants of the AugUR study using a multiplex quantitative PCR-based assay determining the ratio between the telomere product and a single-copy gene product (T/S ratio). AMD was assessed by manual grading of color fundus images using the Three Continent AMD Consortium Severity Scale.Among the 2262 individuals 70 to 95 years old (627 with AMD and 1635 without AMD), RTL was significantly shorter in individuals with AMD compared to AMD-free participants. In age- and sex-adjusted logistic regression analyses, we observed an 8% higher odds for AMD per 0.1 unit shorter RTL (odds ratio [OR] = 1.08; 95% confidence interval [CI], 1.02-1.14; P = 0.005). The estimates remained stable when adjusted for smoking, high-density lipoprotein cholesterol, cardiovascular disease, diabetes, and hypertension. Interestingly, this association was only present in women (OR = 1.14; 95% CI, 1.06-1.23; P0.001), but not in men (OR = 1.01; 95% CI, 0.93-1.10; P = 0.76). A significant sex-by-RTL interaction on AMD was detected (P = 0.043).Our results show an association of RTL with AMD that was restricted to women. This is in line with altered reactive oxygen species levels and higher telomerase activity in women and provides an indication for a sex-differential pathway for oxidative stress and AMD.

Aim: To model a complex retinal disease such as age-related macular degeneration (AMD) in vitro, we aimed to combine genetic and environmental risk factors in a retinal pigment epithelium (RPE) cell culture model generated via induced pluripotent stem cells (iPSCs) from subjects with an extremely high and an extremely low genetic disease risk. As an external stimulus, we chose defined oxidative stress conditions. Methods: Patients were genotyped for known AMD-associated genetic variants and their individual genetic risk score (GRS) was calculated defining individual iPSC-RPE cell lines which reflect the extreme ends of the genetic risk for AMD. Sodium iodate (NaIO3, SI) was used to induce oxidative stress and cellular responses were followed by analyzing nuclear factor erythroid 2-related factor 2 (NRF2) pathway activation by mRNA and protein expression. Results: We present a collection of eight iPSC-RPE cell lines, with four each harboring an extreme low or an extreme high GRS for AMD. RPE identity was verified structurally and functionally. We found that 24 and 72 h of SI treatment induced a significant upregulation of NRF2 response genes HMOX1 and NQO1, without showing cytotoxic effects or negatively influencing RPE cell integrity. High- vs. low-risk cell lines revealed similar first line defenses in oxidative stress response mediated through the NRF2 pathway. Conclusion: Delineating the NRF2-mediated oxidative stress response was sought in iPSC-RPE cell lines with maximally divergent genetic AMD risk profiles. Under the specific stress conditions chosen, our data indicate that genetic predisposition to AMD may not exert a major influence on the NRF2 signaling pathway.

Imaging technology and machine learning algorithms for disease classification set the stage for high-throughput phenotyping and promising new avenues for genome-wide association studies (GWAS). Despite emerging algorithms, there has been no successful application in GWAS so far. We establish machine learning-based phenotyping in genetic association analysis as misclassification problem. To evaluate chances and challenges, we performed a GWAS based on automatically classified age-related macular degeneration (AMD) in UK Biobank (images from 135,500 eyes; 68,400 persons). We quantified misclassification of automatically derived AMD in internal validation data (4,001 eyes; 2,013 persons) and developed a maximum likelihood approach (MLA) to account for it when estimating genetic association. We demonstrate that our MLA guards against bias and artifacts in simulation studies. By combining a GWAS on automatically derived AMD and our MLA in UK Biobank data, we were able to dissect true association (ARMS2/HTRA1, CFH) from artifacts (near HERC2) and identified eye color as associated with the misclassification. On this example, we provide a proof-of-concept that a GWAS using machine learning-derived disease classification yields relevant results and that misclassification needs to be considered in analysis. These findings generalize to other phenotypes and emphasize the utility of genetic data for understanding misclassification structure of machine learning algorithms.

ZusammenfassungDas Bestrophin-1-Gen (BEST1) codiert für ein integrales Membranprotein und findet sich im basolateralen Aspekt des retinalen Pigmentepithels. Mutationen im BEST1 sind mit einer heterogenen Gruppe von erblichen Netzhautdystrophien assoziiert, den sog. Bestrophinopathien, die schon in jüngerem Alter zu einer Beeinträchtigung des Sehvermögens führen können. Die einzelnen Krankheitsbilder sind anhand ihrer phänotypischen Merkmale und Erbgänge abgrenzbar. Während die meisten BEST1-Mutationen einem autosomal-dominanten Erbgang folgen, bei dem bereits eine defekte Genkopie zur Erkrankung führt, sind bei der autosomal-rezessiven Bestrophinopathie heterozygote Mutationsträger i. d. R. symptomfrei. In diesem Übersichtsartikel soll am Beispiel der Bestrophinopathien die Bedeutung der Kenntnis von mutationsabhängigen Mechanismen für das Verständnis der Pathogenese, aber auch für die Entwicklung von zukünftigen Therapieansätzen, hervorgehoben werden.

PURPOSE. To systematically analyze thicknesses of retinal layers in an older population and their link to early age-related macular degeneration (AMD). METHODS. In the AugUR baseline survey from a population aged >= 70 years, we conducted multimodal retinal imaging, including spectral-domain optical coherence tomography. Autosegmentation of eight distinct retinal layers was followed by manual correction of segmentation errors. AMD status was graded on color fundus images according to the Three Continent AMD Consortium Severity Scale. We tested the association of early AMD on retinal layer thicknesses by using linear mixed models and replicated significant results in independent data also from the AugUR platform. RESULTS. When comparing layer thicknesses between early AMD and no AMD (822 eyes, 449 participants), the retinal pigment epithelium/Bruch's membrane complex demonstrated a statistically significant thickening (e.g., P = 6.41 x 10(-92) for severe early versus no AMD) and photoreceptor layers showed a significant thinning. Autosegmented retinal layer thicknesses revealed similar associations as manually corrected values but underestimated some effects. Independent replication analysis in 1026 eyes (546 participants) confirmed associations (e.g., P = 9.38 x 10(-36) for retinal pigment epithelium/Bruch's membrane complex, severe early versus no AMD). CONCLUSIONS. This first population-based study on spectral-domain optical coherence tomography-derived retinal layer thicknesses in a total of similar to 1000 individuals provides insights into the reliability of autosegmentation and layer-specific reference values for an older population. Our findings show a difference in thicknesses between early AMD and no AMD for some retinal layers, suggesting these as potential imaging biomarkers. The thinning of photoreceptor layers substantiates a photoreceptor cell loss/damage already occurring in early AMD.

Background: Individuals aged 70+ were most threatened by COVID-19 and most targeted by shielding recommendations. However, there is limited understanding of the situation of this high-risk population during lockdown. Methods: We derived information via a written self-completion questionnaire sent out to our population-based AugUR study participants (aged 70+, living in/near Regensburg, Germany) shortly after the lift of the curfew in spring 2020 in Bavaria, Germany. This was combined with data from previous AugUR study center visits including medical history assessment, medical exams, and bio-probing, which enabled the comparison of pre- and during-pandemic assessments in the very same individuals. Results: Among 1,850 survey participants (73–98 years; net-response 89%), 74% were at increased risk for severe COVID-19 according to medical conditions (75% extrapolated to the German population aged 70+). Despite 92% have potentially been exposed, only four reported SARS-CoV-2 infection (0.2%). COVID-19 related symptoms were reported by 23%. Regarding lifestyle changes since lockdown, we found no trend towards increased smoking or drinking alcohol, but 34% reported increased sedentary behavior and 29% refrained from medical appointments. Worse QOL was perceived by 38%. Particularly women and the more educated were susceptible to these changes. When comparing lifestyle differences between survey and previous visit, the pattern was similar. Conclusions: Our presented data will help understand the situation of this vulnerable group in the pandemic. While a majority of individuals reported no changes towards a less healthy life style, about one third would benefit from help to sustain a healthy lifestyle when accommodating future strategies.

Bestrophin 1 (Das Bestrophin-1-Gen (

Imaging technology and machine learning algorithms for disease classification set the stage for high-throughput phenotyping and promising new avenues for genome-wide association studies (GWAS). Despite emerging algorithms, there has been no successful application in GWAS so far. We established machine learning based disease classification in genetic association analysis as a misclassification problem. To evaluate chances and challenges, we performed a GWAS based on automated classification of age-related macular degeneration (AMD) in UK Biobank (images from 135,500 eyes; 68,400 persons). We quantified misclassification of automatically derived AMD in internal validation data (images from 4,001 eyes; 2,013 persons) and developed a maximum likelihood approach (MLA) to account for it when estimating genetic association. We demonstrate that our MLA guards against bias and artefacts in simulation studies. By combining a GWAS on automatically derived AMD classification and our MLA in UK Biobank data, we were able to dissect true association (ARMS2/HTRA1, CFH) from artefacts (near HERC2) and to identify eye color as relevant source of misclassification. On this example of AMD, we are able to provide a proof-of-concept that a GWAS using machine learning derived disease classification yields relevant results and that misclassification needs to be considered in the analysis. These findings generalize to other phenotypes and also emphasize the utility of genetic data for understanding misclassification structure of machine learning algorithms.

Background Advanced age-related macular degeneration (AMD) is a leading cause of blindness. While around half of the genetic contribution to advanced AMD has been uncovered, little is known about the genetic architecture of early AMD. Methods To identify genetic factors for early AMD, we conducted a genome-wide association study (GWAS) meta-analysis (14,034 cases, 91,214 controls, 11 sources of data including the International AMD Genomics Consortium, IAMDGC, and UK Biobank, UKBB). We ascertained early AMD via color fundus photographs by manual grading for 10 sources and via an automated machine learning approach for > 170,000 photographs from UKBB. We searched for early AMD loci via GWAS and via a candidate approach based on 14 previously suggested early AMD variants. Results Altogether, we identified 10 independent loci with statistical significance for early AMD: (i) 8 from our GWAS with genome-wide significance (P − 8), (ii) one previously suggested locus with experiment-wise significance (P ARMS2/HTRA1, CFH, C2, C3, CETP, TNFRSF10A, VEGFA, APOE), except two that have not yet been identified with statistical significance for any AMD. Among the 17 genes within these two loci, in-silico functional annotation suggested CD46 and TYR as the most likely responsible genes. Presence or absence of an early AMD effect distinguished the known pathways of advanced AMD genetics (complement/lipid pathways versus extracellular matrix metabolism). Conclusions Our GWAS on early AMD identified novel loci, highlighted shared and distinct genetics between early and advanced AMD and provides insights into AMD etiology. Our data provide a resource comparable in size to the existing IAMDGC data on advanced AMD genetics enabling a joint view. The biological relevance of this joint view is underscored by the ability of early AMD effects to differentiate the major pathways for advanced AMD.

ZusammenfassungDie Suche nach kausalen Therapieoptionen für degenerative Netzhauterkrankungen kann mit einem detaillierten Verständnis pathologischer Vorgänge gezielt vorangetrieben werden. Alternativ kann sie sich auch auf einen eher ungerichteten Suchansatz für therapeutische Wirkstoffe verlassen. Für beide Forschungsansätze werden In-vitro- und, falls möglich, auch In-vivo-Krankheitsmodelle benötigt, die eine möglichst genaue Abbildung des primären Ortes der Schädigung reflektieren. Tiermodelle unterliegen Einschränkungen und können oft nur dezidierte Aspekte eines komplexen Krankheitsprozesses abbilden. Primärkulturen von Zelltypen des hinteren Augenpols sind lediglich invasiv bzw. post mortem zugänglich und aufgrund ihrer raschen Seneszenz nur ungenügend geeignet für zeitlich anspruchsvolle Analysen oder pharmakologische Suchansätze. Immortalisierte retinale Zelllinien wiederum unterscheiden sich in einigen Aspekten zu sehr von den nativen Zelltypen. Eine vielversprechende Alternative bieten induzierte pluripotente Stammzellen (iPSCs). Sie sind wenig invasiv zugänglich, patientenspezifisch generierbar, uneingeschränkt vermehrbar und können aufgrund ihrer Pluripotenz bereits jetzt in einige retinale Zelltypen gezielt ausdifferenziert werden. Diese iPSC-abgeleiteten retinalen Zellen gleichen nativen Zellen in vielen charakteristischen Schlüsseleigenschaften. In diesem Übersichtsartikel werden bereits etablierte In-vivo-und In-vitro-Krankheitsmodelle degenerativer Netzhauterkrankungen vorgestellt und das Potenzial von iPSCs für eine personalisierte In-vitro-Modellierung ausgeleuchtet. Darüber hinaus werden bisher etablierte iPSC-abgeleitete Zelltypen des hinteren Augenpols – insbesondere Zellen des retinalen Pigmentepithels – detaillierter betrachtet und ein Ausblick für das Potenzial dieser Zellen in der allgemeinen ophthalmologischen Forschung gegeben.

Importance Advanced age-related macular degeneration (AMD) is a leading cause of blindness in Western countries. Causal, modifiable risk factors need to be identified to develop preventive measures for advanced AMD. Objective To assess whether smoking, alcohol consumption, blood pressure, body mass index, and glycemic traits are associated with increased risk of advanced AMD. Design, Setting, Participants This study used 2-sample mendelian randomization. Genetic instruments composed of variants associated with risk factors at genome-wide significance (P

Aufgrund der demografischen und gesellschaftlichen Entwicklung ist die Anzahl der Menschen hoheren Lebensalters gestiegen, die in Seniorenheimen vollstationar gepflegt werden. Mit dem Wechsel in ein Heim wird die arztliche Versorgung komplizierter; verschiedene regionale Studien weisen insbesondere auf eine ambulante facharztliche Unterversorgung hin. Vor diesem Hintergrund wurde in dieser Studie die aktuelle ophthalmologische Versorgung in Seniorenheimen in Deutschland untersucht. Diese prospektive, multizentrische Querschnittstudie wurde durch 14 Studienzentren in Deutschland im Zeitraum von 2014 bis 2016 durchgefuhrt. Insgesamt wurden Bewohner von 32 Einrichtungen nach Genehmigungen durch die zustandigen Ethikkommissionen untersucht. Die standardisierte augenarztliche Untersuchung beinhaltete Anamnese, Refraktion, Visusbestimmung, Tonometrie, Spaltlampenuntersuchung und Funduskopie in Mydriasis. Alle Untersuchungen fanden jeweils vor Ort in den Heimen statt. Der augenarztliche Behandlungsbedarf wurde charakterisiert, und die Daten wurden deskriptiv und mittels logistischer Regression ausgewertet. Insgesamt wurden 600 Bewohner (434 Frauen und 166 Manner) zwischen 50 und 104 Jahren untersucht. Fur 368 Personen (61%) ergab sich ein ophthalmologischer Befund, der eine weitere Behandlung erforderte. Zu den haufigsten Diagnosen des Vorderabschnitts zahlten eine visusrelevante Katarakt (315; 53%), Veranderungen der Augenlider (127; 21%), Benetzungsstorungen (57; 10%) und Nachstar (43; 7%). Bei 63 (11%) Bewohnern zeigte sich ein Glaukomverdacht, und bei 55 (9%) bestatigte sich die Diagnose eines vorbekannten Glaukoms, welches jedoch bei einem Drittel unzureichend oder gar nicht therapiert wurde. Funduskopisch zeigten sich bei 236 Bewohnern (39%) Zeichen einer altersabhangigen Makuladegeneration (AMD). Lediglich 52% der Senioren waren innerhalb der letzten 5 Jahre augenarztlich untersucht worden. 39% der Bewohner gaben an, dass sie sich aktuell nicht in der Lage sehen wurden, einen Augenarzt zu konsultieren. Insgesamt wurden 3,7% der untersuchten Bewohner von den Studienarzten als bettlagerig eingestuft. Berichtete Hurden waren vorwiegend Transport und fehlende Unterstutzung/Begleitung. Die vorliegende Erhebung zeigt ein erhebliches ophthalmologisches Versorgungsdefizit in deutschen Seniorenheimen. Neue bzw. eine Erweiterung derzeitiger Versorgungsmodelle sind dringend notwendig.

Zusammenfassung Der gemeinsame Endpunkt vieler Netzhautdegenerationen ist ein Zelluntergang im retinalen Pigmentepithel und/oder der neurosensorischen Retina und ein damit verbundener irreversibler Visusverlust. Therapieansätze in fortgeschrittenen Erkrankungsstadien müssen folglich ebenfalls den Ersatz dieser verloren gegangenen Zellen und Gewebe adressieren. Hier zeichnen sich in den letzten Jahren vor allem auf dem Gebiet der stammzellbasierten zellulären Transplantationstherapie rasante Fortschritte in Grundlagenforschung und klinischer Anwendung ab. Besonders die induzierten pluripotenten Stammzellen scheinen die personalisierte Medizin signifikant voranbringen zu können, falls es gelingt wesentliche Bedenken und Limitationen zu überwinden. Diese Übersicht benennt retinale Krankheitsbilder, bei denen Zelltherapie eine potenzielle Therapieoption darstellt, und gibt einen kurzen Einblick in bisherige Therapiemöglichkeiten. Darüber hinaus werden insbesondere die potenziellen Anwendungsbereiche induzierter pluripotenter Stammzellen mit ihren Vorteilen, aber auch Problemen beleuchtet. Der Hauptfokus liegt auf dem stammzellbasierten Ersatz des retinalen Pigmentepithels, da dieser im Hinblick auf eine therapeutische Anwendung am Menschen, im Vergleich zu anderen Zellen der neurosensorischen Netzhaut, die größten Fortschritte verzeichnet. Abschließend wird ein Überblick über bereits laufende klinische Studien zur Therapie von Netzhautdegenerationen mittels stammzellbasierter zellulärer Transplantationstherapie gegeben.

IMPORTANCE: Age-related macular degeneration (AMD) is a common threat to vision loss in individuals older than 50 years. While neovascular complications in AMD are treatable, there is currently no therapy for geographic atrophy secondary to AMD. Geographic atrophy lesion progression over time shows considerable interindividual variability, but little is known about prognostic factors. OBJECTIVE: To elucidate the contribution of common genetic variants to geographic atrophy lesion growth. DESIGN, SETTING, AND PARTICIPANTS: This pooled analysis combined 4 independent studies: the Fundus Autofluorescence Imaging in Age-Related Macular Degeneration (FAM) study, the Directional Spread in Geographic Atrophy (DSGA) study, the Age-Related Eye Disease Study (AREDS), and the Geographic Atrophy Treatment Evaluation (GATE) study. Each provided data for geographic atrophy lesion growth in specific designs. Patients with geographic atrophy secondary to AMD were recruited to these studies. Genotypes were retrieved through the database of Genotypes and Phenotypes (for AREDS) or generated at the Cologne Center for Genomics (for FAM, DSGA, and GATE). MAIN OUTCOMES: The correlation between square root–transformed geographic atrophy growth rate and 7 596 219 genetic variants passing quality control was estimated using linear regression. The calculations were adjusted for known factors influencing geographic atrophy growth, such as the presence of bilateral geographic atrophy as well as the number of lesion spots and follow-up times. MAIN OUTCOMES AND MEASURES: Slopes per allele, 95% CIs, and P values of genetic variants correlated with geographic atrophy lesion growth. RESULTS: A total of 935 patients (mean [SD] age, 74.7 [7.8] years; 547 female participants [59.0%]) were included. Two gene loci with conservative genome-wide significance were identified. Each minor allele of the genome-wide associated variants increased the geographic atrophy growth rate by a mean of about 15% or 0.05 mm per year. Gene prioritization within each locus suggests the protein arginine methyltransferase 6 gene (PRMT6; chromosome 1; slope, 0.046 [95% CI, 0.026-0.066]; P = 4.09 × 10(−8)) and the lanosterol synthase gene (LSS; chromosome 21; slope, 0.105 [95% CI, 0.068-0.143]; P = 4.07 × 10(−7)) as the most likely progression-associated genes. CONCLUSIONS AND RELEVANCE: These data provide further insight into the genetic architecture of geographic atrophy lesion growth. Geographic atrophy is a clinical outcome with a high medical need for effective therapy. The genes PRMT6 and LSS are promising candidates for future studies aimed at understanding functional aspects of geographic atrophy progression and also for designing novel and targeted treatment options.

Misclassification in binary outcomes can severely bias effect estimates of regression models when the models are naively applied to error-prone data. Here, we discuss response misclassification in studies on the special class of bilateral diseases. Such diseases can affect neither, one, or both entities of a paired organ, for example, the eyes or ears. If measurements are available on both organ entities, disease occurrence in a person is often defined as disease occurrence in at least one entity. In this setting, there are two reasons for response misclassification: (a) ignorance of missing disease assessment in one of the two entities and (b) error-prone disease assessment in the single entities. We investigate the consequences of ignoring both types of response misclassification and present an approach to adjust the bias from misclassification by optimizing an adequate likelihood function. The inherent modelling assumptions and problems in case of entity-specific misclassification are discussed. This work was motivated by studies on age-related macular degeneration (AMD), a disease that can occur separately in each eye of a person. We illustrate and discuss the proposed analysis approach based on real-world data of a study on AMD and simulated data.

The availability of otherwise not readily accessible intraocular cells via induced pluripotent stem cell (iPSC) technology offers great potential for disease modelling, drug screening, and cell-based transplantation therapy in degenerative ocular disorders. Direct differentiation of iPSCs into retinal pigment epithelium (RPE) is particularly straightforward, and iPSC-derived RPE cell cultures have been demonstrated to yield pure populations of functional cells that display many features of native RPE. Here, I describe a protocol for the generation of iPSC-derived RPE monolayer, their propagation, and cryostorage. A reliable monitoring for functional cell differentiation is achieved by measuring transepithelial resistance.

The availability of otherwise not readily accessible intraocular cells via induced pluripotent stem cell (iPSC) technology offers great potential for disease modelling, drug screening, and cell-based transplantation therapy in degenerative ocular disorders. Direct differentiation of iPSCs into retinal pigment epithelium (RPE) is particularly straightforward, and iPSC-derived RPE cell cultures have been demonstrated to yield pure populations of functional cells that display many features of native RPE. Here, I describe a protocol for the generation of iPSC-derived RPE monolayer, their propagation, and cryostorage. A reliable monitoring for functional cell differentiation is achieved by measuring transepithelial resistance.

Die altersbedingte Makuladegeneration (AMD) ist die Hauptursache fur Erblindung in Industrielandern. Populationsbasierte epidemiologische Untersuchungen liefern wichtige Daten zu Pravalenz, Inzidenz, Risikofaktoren und Zukunftstrends. In diesem Ubersichtsbeitrag werden die wichtigsten epidemiologischen Studien zur AMD, ihre Methodik sowie die daraus gewonnenen Erkenntnisse und deren Ubertragbarkeit auf Deutschland dargestellt. Die wesentlichen Risikofaktoren sowohl fur die Entstehung als auch fur die Progression der AMD werden aufgefuhrt und hinsichtlich der existierenden Evidenz bewertet. Zukunftige Herausforderungen wie die Standardisierung von Klassifizierungssystemen und der Einsatz neuerer retinaler Bildgebung in epidemiologischen Studien werden diskutiert. In Deutschland gibt es aktuell nur wenig epidemiologische Daten zur AMD und somit einen hohen Nachholbedarf an epidemiologischer Forschung in der Augenheilkunde. Dieser wird dank verschiedener neuerer populationsbasierter Studien derzeit aufgearbeitet.

Age-related macular degeneration (AMD) is a chronic degenerative disease of the central retina and a major cause of vision impairment and blindness with millions of people affected in the elderly population. In recent years, considerable efforts have been made to understand disease pathology with the long-term goal of designing novel and effective treatment options for this devastating disease. Although striking advances in treating the neovascular stage of late AMD have occurred, no therapy is available for almost half of all AMD patients, specifically those who are affected by the atrophic form of the disease. This review highlights current knowledge on the genetic factors associated with early- and late-stage forms of the disease. It also summarizes the findings regarding the extent to which these factors may play a role in the transition from one disease stage to another, and it emphasizes the need to explore further the underlying mechanisms for both development and progression of this disease as a starting point for designing innovative therapies for it.

Best vitelliform macular dystrophy (BD), autosomal dominant vitreoretinochoroidopathy (ADVIRC), and the autosomal recessive bestrophinopathy (ARB), together known as the bestrophinopathies, are caused by mutations in the bestrophin-1 (BEST1) gene affecting anion transport through the plasma membrane of the retinal pigment epithelium (RPE). To date, while no treatment exists a better understanding of BEST1-related pathogenesis may help to define therapeutic targets. Here, we systematically characterize functional consequences of mutant BEST1 in thirteen RPE patient cell lines differentiated from human induced pluripotent stem cells (hiPSCs). Both BD and ARB hiPSC-RPEs display a strong reduction of BEST1-mediated anion transport function compared to control, while ADVIRC mutations trigger an increased anion permeability suggesting a stabilized open state condition of channel gating. Furthermore, BD and ARB hiPSC-RPEs differ by the degree of mutant protein turnover and by the site of subcellular protein quality control with adverse effects on lysosomal pH only in the BD-related cell lines. The latter finding is consistent with an altered processing of catalytic enzymes in the lysosomes. The present study provides a deeper insight into distinct molecular mechanisms of the three bestrophinopathies facilitating functional categorization of the more than 300 known BEST1 mutations that result into the distinct retinal phenotypes.

Today, the search for therapeutic options to treat retinal degeneration often relies on an in-depth understanding of the underlying pathological events. Alternatively, it is conceivable to search, in an undirected screening approach, for chemical compounds affecting disease outcome. For both approaches, there is an urgent need for in vitro and, ideally, in vivo disease models that adequately reflect the site of pathology. Currently available animal models possess limitations as they often develop only defined aspects of disease. Primary cell cultures, derived from the posterior pole of the eye, can only be obtained after invasive surgery or are available post mortem, but due to rapid cell senescence are not suited for long-term analysis. Immortalized retinal cell lines, on the other hand, differ in many aspects from native cells. In this situation, a promising alternative could arise from induced pluripotent stem cells (iPSCs). This cell species can be generated via non-invasive techniques, they are patient-specific, can be propagated indefinitely, and theoretically can be differentiated in all types of retinal cells due to their pluripotent capacities. Importantly, the iPSC-derived retinal cells greatly resemble native cells in many characteristic traits. In this review we present a selection of established in vivo und in vitro models for retinal degenerative disease. We also discuss the potential of iPSCs for personalized in vitro modelling and provide an overview of existent iPSC-derived cell types of the posterior pole, particularly for cells of the retinal pigment epithelium. We finally give an outlook for the potential of such cells for basic research in ophthalmology.Die Suche nach kausalen Therapieoptionen für degenerative Netzhauterkrankungen kann mit einem detaillierten Verständnis pathologischer Vorgänge gezielt vorangetrieben werden. Alternativ kann sie sich auch auf einen eher ungerichteten Suchansatz für therapeutische Wirkstoffe verlassen. Für beide Forschungsansätze werden In-vitro- und, falls möglich, auch In-vivo-Krankheitsmodelle benötigt, die eine möglichst genaue Abbildung des primären Ortes der Schädigung reflektieren. Tiermodelle unterliegen Einschränkungen und können oft nur dezidierte Aspekte eines komplexen Krankheitsprozesses abbilden. Primärkulturen von Zelltypen des hinteren Augenpols sind lediglich invasiv bzw. post mortem zugänglich und aufgrund ihrer raschen Seneszenz nur ungenügend geeignet für zeitlich anspruchsvolle Analysen oder pharmakologische Suchansätze. Immortalisierte retinale Zelllinien wiederum unterscheiden sich in einigen Aspekten zu sehr von den nativen Zelltypen. Eine vielversprechende Alternative bieten induzierte pluripotente Stammzellen (iPSCs). Sie sind wenig invasiv zugänglich, patientenspezifisch generierbar, uneingeschränkt vermehrbar und können aufgrund ihrer Pluripotenz bereits jetzt in einige retinale Zelltypen gezielt ausdifferenziert werden. Diese iPSC-abgeleiteten retinalen Zellen gleichen nativen Zellen in vielen charakteristischen Schlüsseleigenschaften. In diesem Übersichtsartikel werden bereits etablierte In-vivo-und In-vitro-Krankheitsmodelle degenerativer Netzhauterkrankungen vorgestellt und das Potenzial von iPSCs für eine personalisierte In-vitro-Modellierung ausgeleuchtet. Darüber hinaus werden bisher etablierte iPSC-abgeleitete Zelltypen des hinteren Augenpols – insbesondere Zellen des retinalen Pigmentepithels – detaillierter betrachtet und ein Ausblick für das Potenzial dieser Zellen in der allgemeinen ophthalmologischen Forschung gegeben.

Purpose: Age-related macular degeneration (AMD) is a common threat to vision. While classification of disease stages is critical to understanding disease risk and progression, several systems based on color fundus photographs are known. Most of these require in-depth and time-consuming analysis of fundus images. Herein, we present an automated computer-based classification algorithm.Design: Algorithm development for AMD classification based on a large collection of color fundus images. Validation is performed on a cross-sectional, population-based study.Participants: We included 120 656 manually graded color fundus images from 3654 Age-Related Eye Disease Study (AREDS) participants. AREDS participants were >55 years of age, and non-AMD sight-threatening diseases were excluded at recruitment. In addition, performance of our algorithm was evaluated in 5555 fundus images from the population-based Kooperative Gesundheitsforschung in der Region Augsburg (KORA; Cooperative Health Research in the Region of Augsburg) study.Methods: We defined 13 classes (9 AREDS steps, 3 late AMD stages, and 1 for ungradable images) and trained several convolution deep learning architectures. An ensemble of network architectures improved prediction accuracy. An independent dataset was used to evaluate the performance of our algorithm in a population-based study.Main Outcome Measures: kappa Statistics and accuracy to evaluate the concordance between predicted and expert human grader classification.Results: A network ensemble of 6 different neural net architectures predicted the 13 classes in the AREDS test set with a quadratic weighted kappa of 92% (95% confidence interval, 89%-92%) and an overall accuracy of 63.3%. In the independent KORA dataset, images wrongly classified as AMD were mainly the result of a macular reflex observed in young individuals. By restricting the KORA analysis to individuals >55 years of age and prior exclusion of other retinopathies, the weighted and unweighted kappa increased to 50% and 63%, respectively. Importantly, the algorithm detected 84.2% of all fundus images with definite signs of early or late AMD. Overall, 94.3% of healthy fundus images were classified correctly.Conclusions: Our deep learning algoritm revealed a weighted kappa outperforming human graders in the AREDS study and is suitable to classify AMD fundus images in other datasets using individuals >55 years of age.

Human pluripotent stem cells (hPSCs) are increasingly gaining attention in biomedicine as valuable resources to establish patient-derived cell culture models of the cell type known to express the primary pathology. The idea of “a patient in a dish” aims at basic, but also clinical, applications with the promise to mimic individual genetic and metabolic complexities barely reflected in current invertebrate or vertebrate animal model systems. This may particularly be true for the inherited and complex diseases of the retina, as this tissue has anatomical and physiological aspects unique to the human eye. For example, the complex age-related macular degeneration (AMD), the leading cause of blindness in Western societies, can be attributed to a large number of genetic and individual factors with so far unclear modes of mutual interaction. Here, we review the current status and future prospects of utilizing hPSCs, specifically induced pluripotent stem cells (iPSCs), in basic and clinical AMD research, but also in assessing potential treatment options. We provide an outline of concepts for disease modelling and summarize ongoing and projected clinical trials for stem cell-based therapy in late-stage AMD.

While age-related macular degeneration (AMD) poses an important personal and public health burden, comparing epidemiological studies on AMD is hampered by differing approaches to classify AMD. In our AugUR study survey, recruiting residents from in/around Regensburg, Germany, aged 70+, we analyzed the AMD status derived from color fundus images applying two different classification systems. Based on 1,040 participants with gradable fundus images for at least one eye, we show that including individuals with only one gradable eye (n = 155) underestimates AMD prevalence and we provide a correction procedure. Bias-corrected and standardized to the Bavarian population, late AMD prevalence is 7.3% (95% confidence interval = [5.4; 9.4]). We find substantially different prevalence estimates for “early/intermediate AMD” depending on the classification system: 45.3% (95%-CI = [41.8; 48.7]) applying the Clinical Classification (early/intermediate AMD) or 17.1% (95%-CI = [14.6; 19.7]) applying the Three Continent AMD Consortium Severity Scale (mild/moderate/severe early AMD). We thus provide a first effort to grade AMD in a complete study with different classification systems, a first approach for bias-correction from individuals with only one gradable eye, and the first AMD prevalence estimates from a German elderly population. Our results underscore substantial differences for early/intermediate AMD prevalence estimates between classification systems and an urgent need for harmonization.

A significant portion of patients diagnosed with vitelliform macular dystrophy (VMD) do not carry causative mutations in the classic VMD genes BEST1 or PRPH2. We therefore performed a mutational screen in a cohort of 106 BEST1/PRPH2-negative VMD patients in two genes encoding secreted interphotoreceptor matrix proteoglycans-1 and -2 (IMPG1 and IMPG2). We identified two novel mutations in IMPG1 in two simplex VMD cases with disease onset in their early childhood, a heterozygous p.(Leu238Pro) missense mutation and a homozygous c.807 + 5G > A splice site mutation. The latter induced partial skipping of exon 7 of IMPG1 in an in vitro splicing assay. Furthermore, we found heterozygous mutations including three stop [p.(Glu226*), p.(Ser522*), p.(Gln856*)] and five missense mutations [p.(Ala243Pro), p.(Gly1008Asp), p.(Phe1016Ser), p.(Tyr1042Cys), p.(Cys1077Phe)] in the IMPG2 gene, one of them, p.(Cys1077Phe), previously associated with VMD. Asymptomatic carriers of the p.(Ala243Pro) and p.(Cys1077Phe) mutations show subtle foveal irregularities that could characterize a subclinical stage of disease. Taken together, our results provide further evidence for an involvement of dominant and recessive mutations in IMPG1 and IMPG2 in VMD pathology. There is a remarkable similarity in the clinical appearance of mutation carriers, presenting with bilateral, central, dome-shaped foveal accumulation of yellowish material with preserved integrity of the retinal pigment epithelium (RPE). Clinical symptoms tend to be more severe for IMPG1 mutations.

To determine changes in choroidal thickness in patients with central serous chorioretinopathy (CSCR) during the first 3 months after initial diagnosis and assess variable therapeutic interventions via enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT). In this prospective study, choroidal thickness was measured via EDI-OCT both in the affected and fellow eyes of 10 patients with CSCR at the fovea, as well as at 500 and 1,000 μm both temporal and nasal from the centre of the fovea and at the leakage point (if present), visualised via fluorescein angiography. Follow-up measurements were performed after 2-3 weeks, 6-8 weeks and 3 months. Seven of the 10 patients received additional systemic therapy with oral acetazolamide. A control group of eight healthy subjects was recruited to determine normal choroidal thickness in healthy eyes. The mean age of the 10 patients (9 male, 1 female) in the CSCR group was 42.1 (±9.3) years. The choroid in the affected eyes was significantly thickened at baseline compared to fellow eyes and the eyes of healthy subjects. The choroid in the fellow eyes also revealed a slight thickening at baseline compared to normal eyes. During the 3 month follow-up period, the choroidal thickness of the affected eyes showed a highly significant decrease, but did not reach normal levels. Minor changes could also be observed in the fellow eyes but did not reach statistical significance. In patients with CSCR, the average choroidal thickness not only demonstrated a significant thickening at baseline, but also showed a marked decrease after 3 months, yet not reaching normal levels. Our data indicate that after 3 months, normalisation of choroidal thickness is not yet completed.

Objectives: In a previous study, we have reported the existence of neural crest-derived stem cell-like cells originating from the corneal limbus of juvenile mice (termed murine corneal cells, MCCs). To yield a sufficient number of MCCs, for example, for cell-therapy approaches, here we have investigated MCCs’ ability for extensive proliferation, and we have evaluated their stem cell qualities and genetic stability after large-scale culture. Materials and methods: MCCs were established from corneal limbal tissue of juvenile mice. To determine their cell proliferation and self-renewing potential, MTT tests and an estimation of colony forming unit efficiency were carried out. Multipotency of cell differentiation was examined by applying adipogenic and osteogenic differentiation protocols. Moreover, karyotyping was performed and expression of stem cell markers and cell cycle-associated genes was analysed. Results: MCCs, as primary cells, could be cultured for more than 60 passages. We observed increased cell proliferation and high number of colony forming units (CFUs) after extensive culture. Interestingly, there were no changes in expression of MCC markers. Furthermore, cell differentiation potentials remained comparable with MCCs at early passages. However, karyotyping revealed numeric chromosomal aberrations at higher passages. Moreover, tumour suppressor genes such as p16 and p21 were found to be down-regulated after large-scale cell culture. Conclusions: MCCs immortalize spontaneously after extensive cell culture, but still demonstrate stem cell-like qualities.

Dental stem cells from human exfoliated deciduous teeth (SHED) and dental follicle cells (DFCs) are neural crest-derived stem cells from human dental tissues. Interestingly, SHED and DFCs can successfully differentiate into neuron-like cells. We hypothesized that SHED and DFCs have the same neural cell differentiation potentials. To evaluate neural cell differentiation, we cultivated SHED and DFCs in four different serum-replacement media (SRMs) and analyzed cell morphology, cell proliferation, and gene expression patterns before and after differentiation. In a standard cell culture medium, SHED and DFCs have not only similar cell morphologies, but they also have similar gene expression patterns for known stem cell markers. However, only SHED expressed the neural stem cell marker Pax6. After cultivation in SRMs, cell proliferations of DFCs and SHED were reduced and the cell morphology was spindle-like with long processes. However, differentiated DFCs and SHED had different neural cell marker expression patterns. For example, gene expression of the late neural cell marker microtubule-associated protein 2 was upregulated in DFCs and downregulated in SHED in SRM with the B27 supplement. In contrast, SHED formed neurosphere-like cell clusters in SRM with the B27 supplement, epidermal growth factor, and fibroblast growth factor-2. Moreover, SHED differentially expressed the glial cell marker glial fibrillary acidic protein, which in contrast was weakly or not expressed in DFCs. In conclusion, SHED and DFCs have different neural differentiation potentials under the same cell culture conditions.

In response to cell swelling, volume-regulated anion channels (VRACs) participate in a process known as regulatory volume decrease (RVD). Only recently, first insight into the molecular identity of mammalian VRACs was obtained by the discovery of the leucine-rich repeats containing 8A (LRRC8A) gene. Here, we show that bestrophin 1 (BEST1) but not LRRC8A is crucial for volume regulation in human retinal pigment epithelium (RPE) cells. Whole-cell patch-clamp recordings in RPE derived from human-induced pluripotent stem cells (hiPSC) exhibit an outwardly rectifying chloride current with characteristic functional properties of VRACs. This current is severely reduced in hiPSC-RPE cells derived from macular dystrophy patients with pathologic BEST1 mutations. Disruption of the orthologous mouse gene (Best1(-/-)) does not result in obvious retinal pathology but leads to a severe subfertility phenotype in agreement with minor endogenous expression of Best1 in murine RPE but highly abundant expression in mouse testis. Sperm from Best1(-/-) mice showed reduced motility and abnormal sperm morphology, indicating an inability in RVD. Together, our data suggest that the molecular identity of VRACs is more complex--that is, instead of a single ubiquitous channel, VRACs could be formed by cell type- or tissue-specific subunit composition. Our findings provide the basis to further examine VRAC diversity in normal and diseased cell physiology, which is key to exploring novel therapeutic approaches in VRAC-associated pathologies.

The neural crest is a transient embryonic tissue alongside the lateral margins of the neural folds. It contains cells involved in the development of anterior eye segments such as the cornea. Previous studies have revealed the presence of neural crest-derived stem cells in the cornea of the adult murine eye. However, less is known about cell populations of the developing eye. In this study, we have identified neural crest-derived murine corneal cells (MCCs) with stem cell-like properties derived from the corneal limbus of mice between postnatal days 1 and 8. RT-PCR analysis and immunofluorescence staining demonstrate that MCCs express a unique profile of markers including typical neural crest-originated stem cell transcripts like Sca1. MCCs show a limited self-renewing capacity but possess multipotency under in vitro conditions after differentiation into cells with features resembling adipocytes, osteoblasts and neuronal cells. Interestingly, MCCs could not be isolated from corneas of adult animals. We conclude that MCCs are stem cell-like cells of an early postnatal period of murine eye growth, probably involved in the early development of the postnatal cornea.

Induced pluripotent stem cell (iPSC)-derived retinal pigment epithelium (RPE) has widely been appreciated as a promising tool to model human ocular disease emanating from primary RPE pathology. Here, we describe the successful reprogramming of adult human dermal fibroblasts to iPSCs and their differentiation to pure expandable RPE cells with structural and functional features characteristic for native RPE. Fibroblast cultures were established from skin biopsy material and subsequently reprogrammed following polycistronic lentiviral transduction with OCT4, SOX2, KLF4 and L-Myc. Fibroblast-derived iPSCs showed typical morphology, chromosomal integrity and a distinctive stem cell marker profile. Subsequent differentiation resulted in expandable pigmented hexagonal RPE cells. The cells revealed stable RNA expression of mature RPE markers RPE65, RLBP and BEST1. Immunolabelling verified localisation of BEST1 at the basolateral plasma membrane, and scanning electron microscopy showed typical microvilli at the apical side of iPSC-derived RPE cells. Transepithelial resistance was maintained at high levels during cell culture indicating functional formation of tight junctions. Secretion capacity was demonstrated for VEGF-A. Feeding of porcine photoreceptor outer segments revealed the proper ability of these cells for phagocytosis. IPSC-derived RPE cells largely maintained these properties after cryopreservation. Together, our study underlines that adult dermal fibroblasts can serve as a valuable resource for iPSC-derived RPE with characteristics highly reminiscent of true RPE cells. This will allow its broad application to establish cellular models for RPE-related human diseases. Electronic supplementary material The online version of this article (doi:10.1007/s12017-014-8308-8) contains supplementary material, which is available to authorized users.