Horst Brewitt

Dry eye disease : The scale of the problem

Dry eye disease, or keratoconjunctivitis sicca, is among the most frequently established diagnoses in ophthalmology; in Germany, one in four patients consulting an ophthalmologist complains of the symptoms of dry eye. Although epidemiological studies investigating the prevalence of dry eye disease are rare, published studies indicate that up to 20% of adults aged 45 years or more experience dry eye symptoms. Recent studies have shown that immunologic changes play a role in the pathogenesis of dry eye, not only in Sjögrens syndrome, but also in postinfectious and age-related conditions. Despite increasing understanding of the pathogenic factors involved in dry eye disease, there has been a lack of consensus on diagnostic criteria, classification of disease states, and the aims and interpretation of specific diagnostic tests. There is a need, therefore, for standardization of disease terminology and diagnostic tests in order to improve the usefulness of epidemiological and clinical investigation of this important ocular disorder.

[Meibomian glands : part III. Dysfunction - argument for a discrete disease entity and as an important cause of dry eye].

Meibomian gland dysfunction (MGD), mainly synonymous with posterior blepharitis but typically without prominent inflammatory alterations of the lid margin, is a discrete disease entity and a frequent cause of wetting deficiencies of the ocular surface leading to dry eye disease that deserves increased recognition by clinicians. The history, classification, pathology, influencing factors, diagnostics and therapy are explained and discussed. MGD is mainly based on an obstructive mechanism caused by hyperkeratinization of the excretory duct and/or increased viscosity of the secretion (meibum) with subsequent deficiency of the tear film lipid layer. MGD is influenced by the hormonal status and by chemical and mechanical noxes as well as genetic defects and it occurs more frequently in women and generally increases with age. It results in stasis of meibum inside the glands, dilatation of the ductal system and eventually in atrophy and loss of glandular tissue (gland dropout). Careful investigation of the eyelids and lid margins with eversion, if necessary, should therefore be performed in every case of a wetting defect, notably before fitting contact lenses. Particularly important is the inspection of the meibomian orifices and diagnostic expression by mild mechanical compression of the lid.

Morphological Changes of the Corneal Epithelium after Application of Topical Anaesthetic Ointments

The effect of topical anaesthetic ointments (4% cocaine, 4% xylocaine, 0.5% proparacaine, 0.2% oxybuprocaine) on the corneal epithelium of rabbits was examined using a scanning electron microscope. Even after a single application, the more toxic effect of cocaine compared to the other topical anaesthetics was evident. Cocaine caused disruption of both the plasma membrane and the cytoplasm. After a single application, the other preparations caused a marked decrease in the microvilli and microplicae, disruption of the intercellular spaces and the prominence of the cell nucleus which under normal condition is not visible. Repeated applications caused regular cell desquamation and damage to the plasma membrane and cytoplasm. The damage also affected several cell layers. The cell reactions described are clearly a consequence of the topical anaesthetics, as the ointment base itself produced no essential cell damage. The scanning electron microscope findings were supported by results from the transmission electron microscope.

Das trockene Auge als komplexe Fehlregulation der funktionellen Anatomie der Augenoberfläche

ZusammenfassungHintergrundDas trockene Auge ist eine Störung des Tränenfilms, die zu Epithelschäden und einer Veränderung der normalen Homöostase an der Augenoberfläche führt.MethodenEs wurde ein Review der Literatur durchgeführt, um verschiedene Konzepte zum Verständnis des trockenen Auges zu vergleichen und mit einem Fokus auf Mechanismen der integrierenden funktionellen Anatomie der Augenoberfläche. ErgebnisseDas Verständnis der Pathogenese des trockenen Auges hat sich entwickelt von der alleinigen Erkenntnis eines zugrunde liegenden Tränenmangels über die Betrachtung der Tränenqualität bis zum Konzept der Benetzbarkeit der Augenoberfläche. Allerdings tragen zahlreiche weitere Aspekte wie die Differenzierung des Oberflächenepithels, Innervation, Hormonstatus oder Immunprotektion zur intakten funktionellen Anatomie der Augenoberfläche bei. Es mehren sich Hinweise, dass immunologisch gesteuerte Entzündungsvorgänge einen wichtigen primären oder sekundären pathogenetischen Faktor darstellen. Dies kann vermutlich durch die Zellen des physiologischen Schleimhautimmunsystems (Augen-assoziiertes lymphatisches Gewebe, EALT) reguliert werden. Androgene sind ein wichtiger trophischer Faktor für die Integrität der Augenoberfläche, und ihr Mangel prädisponiert zur Entwicklung von Entzündungen.SchlussfolgerungDas trockene Auge repräsentiert eine komplexe Fehlregulation der funktionellen Anatomie der Augenoberfläche, die von verschiedenen Ursachen ausgehen kann. Eine entstehende immunregulierte Entzündung kann diese Pathomechanismen verknüpfen und im Sinne eines Circulus vitiosus negativ verstärken.AbstractIntroductionDry eye disease is a disorder of the tear film that results in epithelial damage and in a disruption of the normal homeostasis at the ocular surface. It is widespread and causes symptoms ranging from discomfort to blindness.MethodsA review of the existing literature was used to compare different past and recent concepts for the understanding of dry eye disease with a focus on aspects of the integrating functional anatomy of the ocular surface.ResultsThe understanding of the pathogenesis of dry eye disease has proceeded from the mere recognition of a lack of tears to a consideration of their quality and to the concept of wetting of the ocular surface. However, several other aspects as epithelial differentiation, innervation, hormonal status or immune protection contribute to the intact functional anatomy of the ocular surface. Recently it has been recognized that immunologically regulated mechanisms of inflammation represent a primary or secondary pathogenetic factor for dry eye disease. This is conceivably regulated by the cells of the physiological mucosal immune defence system, the eye-associated lymphoid tissue (EALT). Androgens represent an important trophic factor for the ocular surface and their deficiency predisposes to inflammation.ConclusionDry eye disease represents a complex dysregulation of the functional anatomy of the ocular surface that can start from different alterations (e.g. insufficient secretion, defects in wetting or innervation). Immune-based inflammation is able to interconnect and negatively reinforce these different pathomechanisms, resulting in a vicious circle.

Sliding of epithelium in experimental corneal wounds. A scanning electron microscopic study.

The morphological changes in the rabbit cornea due to a linear wound and a central keratectomy and its reepithelization were examined under the scanning electron microscope. After the rounding off and retraction of the edges of the wound, during the first 6 h, the stroma was infiltrated by leucocytes. First of all the superficial epithelial cells migrated over the edges of the wound to protect the exposed cleft in the tissue. After 15 h the basal epithelial cells sent pseudopodia‐like processes of varying lengths into the wound area. The migrating cells were mainly flat. During this phase the primary migration of the basal epithelial cells was followed by subsequent cell layers. In the migration, three types of cells can be distinguished: 1. very flat cells with smooth edges without microprojections, which adapt their shape to the clefts in the damaged stroma, 2. flat cells with considerably folded plasma membrane on the cell surface giving a coral‐like appearence, 3. cells with voluminous cytoplasmic processes. The rapidly sliding epithelium covered the defect with star shaped growths so that after only 48 h a nearly complete closure of the wound was achieved. After 96 h the deep wound was completely covered by epithelium. The epithelial cells did not yet possess their original surface structure in that they had demonstrably fewer microvilli and microplicae than normal. Only after five days at the earliest could the normal surface relief be seen. The surface cells were predominant in the first stage of the healing process and the basal cells only in the second stage.

Kontaktlinsen : Infektionen und Hygiene

Fragestellung: Kontaktlinsenträger sind vermehrt infektionsgefährdet. Welche Faktoren führen zu dem unverhältnismäßig hohen Infektionsrisiko?Patienten: Das Übersichtsreferat soll anhand von Literaturdaten Hintergründe des Infektionsrisikos bei Kontaktlinsenträgern beleuchten.Ergebnisse: Das relative Keratitisrisiko ist abhängig vom Linsenmaterial und der Tragezeit der Kontaktlinsen. Hydrogellinsen bergen ein unverhältnismäßig hohes Infektionsrisiko. Die Häufigkeit von Kontaktlinsenkomplikationen wird ganz allgemein in der Literatur mit bis zu 66% infolge mangelnder Hygiene angegeben. Die allgemeinen Hygienemängel der Kontaktlinsenträger sind deshalb neben patho-physiologischen Mechanismen des Auges ursächlich anzuschuldigen. Das Keimspektrum begünstigt Gram-negative Feuchtkeime wie Pseudomonas, Serratia und Parasiten wie Akanthamöben.Schlußfolgerung: Spezielle Erregerspektren und neue Problemkeime stellen nicht nur den Arzt, sondern auch die Industrie vor die Aufgabe, ihre Hygienemaßnahmen und -produkte neuen Erkenntnissen anzupassen. Austauschlinsensysteme sind ein erster Schritt in diese Richtung, können aber durchaus nicht alle Probleme der Kontaktlinsenträger lösen. Auf die Bedeutung der Kontaktlinsenhygiene und die Anleitung der Patienten in einem Arzt-Patienten-Gespräch wird verwiesen. Die Hygiene auch des Kontaktlinsenanpassers sollte bei dem gesamten Problemkreis nicht vernachlässigt werden.Background: Contact lens wearers are subject to increased risk of infection, and an attempt was made to determine which factors cause the overproportional risk of infection?Patients: The aim of this paper is to explain with appropriate bibliographic support why people who wear contact lenses are at risk of infection.Results: The relative risk of keratitis is a function of the lens material and the wearing time of the contact lenses. Extended wear of hydrogel lenses is associated with an overproportional risk of infection. According to the literature, the frequency of complications in contact lens wearers generally is the result of poor hygiene in 66% of the cases. The general lack of hygiene among contact lens wearers must, therefore, be regarded as one cause among pathophysiological mechanisms of the eye. The microbial spectrum favors gram-negative bacteria living in a wet environment such as Pseudomonas, Serratia and parasites like Acanthamoeba.Conclusion: The specific spectrum of pathogens and new problem organisms not only challenge the fitter but also the manufacturers to adapt hygiene (sanitary) measures and products to the new development. Disposable contact lens systems are the first step, but they do not solve all the problems of contact lens wearers. Therefore, the importance of contact lens hygiene must be especially emphasized when the ophthalmologist is giving instructions to the patient. On the other hand, hygiene should also not be neglected by the contact lens fitters since it is part of the whole problem.

Rasterelektronenmikroskopische Untersuchungen zur lokalen Hornhautverträglichkeit von Betablockeraugentropfen mit und ohne Konservierungsstoffe

The influence of Β-blockers in short- and long-term application on the epithelium of the cornea was studied in rabbits with intact tear film, concentrating not on the completeness of the drug group but on general differences. The new unpreserved Β-blocker timolol was compared on an exemplary level with the following Β-blocker formulas: (1) Β-blocker eye drops with 0.01% of the preservative benzalkonium chloride; (2) Β-blocker eye drops with 0.005% of the preservative benzalkonium chloride, and (3) Β-blocker eye drops with 0.004% of the preservative benzalkonium chloride and the tear substitute poly vinyl alcohol. Exposure time in the short-term test was 30 min, in long-term tests the time was 24 weeks. Any cell damages observed were of only minor importance and rarely of clinical relevance; however, it could be shown that micromorphological cell reactions differed as a function of the preservative concentration. Complete absence of preservatives causes no difference in micromorphologically relevant changes in comparison with the control group. Drugs without preservatives are thus a meaningful alternative for patients with allergies, sensitive eyes or existing impairment of the precorneal film.