Histological characteristics of the posterior lid margin

Purpose The structure of the lid margin is insufficiently understood and defined although it is of obvious importance for ocular surface integrity. In particular the histological structure of the tissues of the normal lid margin and their zonal differentiation is partly unclear. Methods The structure and function of the different zones at the posterior lid margin are explained with a focus on dry eye disease, based on the available literature on the lid margin together with own findings on the histology of normal and pathological tissues from the human lid margin. Results The Meibomian glands (MG) that are of particular significance for the integrity of the ocular surface open still within the cornified epidermis. Their obstructive dysfunction (MGD) is a main cause for dry eye disease. The orifice is followed by the mucocutaneous junction (MCJ) that extends from the abrupt termination of the epidermis to the crest of the inner lid border. The physiological vital stainable line of Marx represents its surface and can be used as a diagnostic tool for the location and functionality of the MG orifices and lacrimal puncta. The marginal conjunctiva starts at the crest of the inner lid border and forms a thickened epithelial cushion. This is the point in closest apposition to the globe, represents the zone that wipes the bulbar surface and distributes the thin pre‐ocular tear film. It is hence termed as the lid wiper and pathological alterations that result in a vital staining are a sensitive early indicator of dry eye disease. Conclusion The margin of the eyelid is an important but yet underestimated structure for the maintenance of the pre‐ocular tear film and of utmost importance for the preservation of ocular surface integrity and for development of dry eye disease. Support DFG KN317/11