Meibomian gland imaging: A review

The meibomian glands of the upper and lower eyelids play a valuable role in secreting the lipid layer of the tear film. Disturbances in meibomian gland function may result in altered secretion and variations in tear composition which may lead to meibomian gland dysfunction and evaporative dry eye, leading to ocular discomfort. To diagnose and monitor the structural and functional changes occurring within the glands of the eyelids, various imaging techniques are available. Some of the methods used to evaluate the tears and therefore the meibum within the tears include evaporimetry, interferometry, tear osmolarity and meibometry. With these techniques, changes in the lipid layer of the tear film can be quantified and alterations in meibomian gland function assessed. Meibography is an additional method that can be used; it has the unique feature of allowing the assessment of meibomian gland morphology during ocular surface disease processes. The aim of this review is to create an improved understanding of the meibomian glands and the ways that they may be investigated in order to expand on the treatment methods available.