Technological advances mean meibography may be used to diagnose MGD
Meibomian gland dysfunction (MGD) is one of the most common causes of an abnormality of the tear film lipid layer and evaporative dry eye.1–5 Numerous risk factors of MGD are reported (Table 1).6 Its prevalence varies between countries from 20% to 60%, with the highest rate in Japan.6 MGD is a chronic, diffuse abnormality of the meibomian glands, commonly characterized by terminal duct obstruction and/or qualitative/quantitative changes in the glandular secretion.7 This may result in alteration of the tear film, symptoms of eye irritation, clinically apparent inflammation and ocular surface disease.7
Meibography is the only clinically in vivo technique to visualize the morphology of the meibomian glands. When using this method, the structure of the meibomian glands, including the ducts and acini, can be observed.8–16 Meibography provides photographic documentation of the meibomian gland under specialized illumination techniques.17 This article is aimed to summarize recent development and investigation in meibography and its clinical relevance.
There are two principles in meibography. One is the transillumination of the everted lid11,18,19 the other is direct illumination, named the non-contact meibography.15,20–22 In the transillumination technique, the eyelid is everted over a light source.11,13,23 The most basic version uses white light, for example from a Finoff transilluminator. This is applied to the cutaneous side of the everted eyelid and allows observation from the palpebral conjunctival surface. Tapie24 was probably first describing evaluation of meibomian glands by transilluminating lids in 1977. He also captured the meibomian glands using infrared film (IR). Jester et al.16 adapted the biosmicroscopic and photographic techniques to improve upon Tapie's technique.16 Subsequently many other groups have used the transillumination IR techniques in meibomian gland observation.11,18,19,25