Three-dimensional volumetric human meibomian gland investigation using polarization-sensitive optical coherence tomography

Anwendungsmöglichkeiten der optischen Kohärenztomographie beim trockenen Auge

Durch die stetige Weiterentwicklung und Verbesserung der Technik hat die optische Kohärenztomographie (OCT) in den letzten Jahren neue Möglichkeiten zur Beurteilung der Strukturen des vorderen Augenabschnittes eröffnet. Aufgrund der Darstellung kleinster Strukturen, wie beispielsweise des Tränenfilms, nimmt die OCT in der Diagnostik und Verlaufsbeurteilung des trockenen Auges eine immer wichtigere Rolle ein. Der vorliegende Beitrag gibt einen Überblick über die derzeitigen Einsatzmöglichkeiten der OCT beim trockenen Auge.

New Technologies in Clinical Trials in Corneal Diseases and Limbal Stem Cell Deficiency: Review from the European Vision Institute Special Interest Focus Group Meeting

To discuss and evaluate new technologies for a better diagnosis of corneal diseases and limbal stem cell deficiency, the outcomes of a consensus process within the European Vision Institute (and of a workshop at the University of Cologne) are outlined. Various technologies are presented and analyzed for their potential clinical use also in defining new end points in clinical trials. The disease areas which are discussed comprise dry eye and ocular surface inflammation, imaging, and corneal neovascularization and corneal grafting/stem cell and cell transplantation. The unmet needs in the abovementioned disease areas are discussed, and realistically achievable new technologies for better diagnosis and use in clinical trials are outlined. To sum up, it can be said that there are several new technologies that can improve current diagnostics in the field of ophthalmology in the near future and will have impact on clinical trial end point design.

The role of meibography in ocular surface diagnostics: A review

The meibomian glands are lipid-secreting glands located in the tarsal plates, whose secretory products cover the tear film, thereby reducing evaporation as well as ensuring lubrication of the ocular surface. The meibomian glands can be visualized at different levels of magnification by infrared meibography, laser confocal microscopy, and optical coherence tomography. These imaging modalities have been subject to much research and progress in clinical practice and have shaped our current understanding of meibomian glands in health and disease. In this review, we explore the evolution of meibography over the past decades, the major contributions of various meibographic modalities, and discuss their clinical significance.

[In vivo Meibomian gland imaging techniques: A review of the literature (French translation of the article)]

Meibomian gland dysfunction (MGD) encompasses a group of complex pathologies of the ocular surface. They represent one of the main etiologies of dry eye but also one of the leading causes of consultation in ophthalmology. Conventional clinical tests (dry eye symptoms, tear film rupture time, glandular expressiveness assessment, or Schirmer's test) allow only an indirect assessment of Meibomian gland function and physiology. Various in vivo investigation methods have therefore been developed to image the meibomian glands such as meibography, optical coherence tomography, ultrasound or in vivo confocal microscopy. Some are accessible in clinical practice, while others remain in the field of clinical research. All these techniques aim to develop a direct structural analysis of the Meibomian glands to help in the diagnosis of DGM but also to better understand the pathophysiology of Meibomian glands. This review of the literature aims to provide an overview of existing imaging modalities and their interest in the evaluation of Meibomian glands and MGD.

In vivo Meibomian gland imaging techniques: A review of the literature

Meibomian gland dysfunction (MGD) includes a group of complex disorders of the ocular surface. It represents one of the main etiologies of dry eye as well as one of the main reasons for patient visits to the ophthalmologist. Classic clinical tests (dry eye symptoms, tear film break-up time, evaluation of gland expressibility or Schirmer's testing) only provide an indirect assessment of the function of the Meibomian glands and the meibum. Various in vivo testing methods have therefore been developed to image the Meibomian glands, such as Meibography, optical coherence tomography, ultrasound, or even in vivo confocal microscopy. Some are accessible in clinical practice, while others are limited to the realm of clinical research. All of these techniques aim to develop a direct structural analysis of the Meibomian glands so as to assist in the diagnosis of MGD as well as to better understand the pathophysiology of the Meibomian glands. This review of the literature hopes to provide an overview of the current imaging modalities and their role in the evaluation of the Meibomian glands and MGD.

Side effects of retinoid therapy on the quality of vision

Retinoids are compounds chemically related to vitamin A, which are frequently used in dermatological practice (1). They are characterized by numerous mechanisms of action leading to normalization of keratinocyte proliferation and maturation. They have anti-seborrhoeic, immunomodulatory and anti-inflammatory effects (1, 2). A number of side effects to retinoid treatment have been recorded; one group of such side effects relates to eyes and vision. Dry eye syndrome and blepharoconjunctivitis are the most common side effects, appearing in 20-50 % of patients treated with retinoids. They often contribute to the occurrence of other side-effects such as eye discomfort and contact lens intolerance. Due to the widespread use in clinical practice, the adverse effects, including ocular side effects, should be studied. To confirm the variety of adverse effects of retinoids, several case reports of rare side-effects are presented.

[A new classification for meibomian gland diseases with in vivo confocal microscopy]

INTRODUCTION

Meibomian gland dysfunction (MGD) is a frequent disorder often associated with dry eye disease. Slit-lamp examination with digital expression of the tarsal Meibomian glands allows examination of the contents of the distal Meibomian gland and the meatus. However, the Meibomian epithelium, interglandular space and proximal secretions cannot be clinically assessed. In vivo confocal microscopy (IVCM) is a rapid and non-invasive imaging technique that provides high-resolution images of the ocular surface and eyelids. The primary objective of the present study was to establish a classification of MGD with IVCM. Secondary objectives were to evaluate this scoring system by analyzing the correlation with OSDI, infrared (IR) meibography and Demodex infestation.

MATERIAL AND METHODS

Forty-six dry eye patients (Ocular Surface Disease Index [OSDI] >13) associated with MGD were enrolled. Ten healthy subjects without dry eye disease or blepharitis were also included as controls. An OSDI questionnaire, clinical examination, IVCM and infrared meibography of the lower lid were performed in all subjects by the same examiner.

RESULTS

A new MGD score was established based on IVCM findings: the first stage was Meibomian obstruction with a clear epithelium, the second stage was an inflammatory state with Meibomian gland obstruction, epithelial and interglandular inflammation, and the last stage was glandular fibrosis. This score was significantly correlated with the meiboscore obtained with infrared meibography (correlation coefficient 0.47, CI95% [0.22-0.66]).

CONCLUSION

IVCM of the Meibomian gland complex complements the clinical examination by determining the stage of dysfunction and may help clinicians evaluate and treat MGD.

Degree of polarization (uniformity) and depolarization index: unambiguous depolarization contrast for optical coherence tomography

The degree of polarization (uniformity) has attracted increased interest as a functional contrast in optical coherence tomography (OCT). However, its computation from a single polarization state suggests an ambiguity that is strongly dependent on a sample's orientation. We here propose an improved metric to present depolarization with respect to the optical system rather than the propagating field. Using numerical simulations and optical frequency domain imaging, we evaluate the conventional DOP(U) for different polarization states and compare its performance with the unambiguous depolarization index.

Dry eye disease: A review of diagnostic approaches and treatments

Dry eye (DE) is a common ocular disease that results in eye discomfort, visual disturbance and substantially affects the quality of life. It has a multifactorial etiology involving tear film instability, increased osmolarity of the tear film and inflammation of the ocular surface with potential damage to the ocular surface. This review discusses the classification, diagnostic approaches and treatments of DE.