Meibomian Gland Dysfunction (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. It may result in alteration of the tear film, symptoms of eye irritation, clinically apparent inflammation, and ocular surface disease.18
Due to recent advances, eye care professionals can now use diagnostic meibomian gland expression to evaluate meibomian gland function and detect nonobvious MGD.19,20,21,22 It is currently understood that meibomian gland function cannot be evaluated without standardized diagnostic expression and that the evaluation of meibomian glands in a thorough eye examination is essential.
Due to its pathophysiology, MGD is chronic and progressive.23,24,25 As is typical of most treatable diseases, the earlier it is detected, the better to prevent further loss of function and sequelae.26,27 The concept that MGD leads to tear film compromise and its sequalae has been known since 1977.28 However, what we know now is that MGD has the potential to affect all of us and not just a particular subgroup of patients.29,30 Recent studies show that a multitude of factors place a patient at risk for MGD.31 Most recently we have learned that evaporative stress itself, for example working in an air-conditioned room, can lead to the development of MGD. Further, any activity that inhibits the blink mechanism, for example working on a computer or reading an iPhone can have an impact. The primary mechanism of action is initiated by any activity that creates conditions to decrease the frequency and efficacy of the blink and to increase evaporative stress.32,33 The translation of this research to eye care practice is that everyone is at risk for MGD.
As MGD becomes better understood, the new paradigm shift of Non-Obvious MGD (NOMGD) increases in awareness. It is believed that NOMGD is the precursor to obvious MGD.34 NOMGD introduces into ophthalmic care the recognition that MGD may be present with or without inflammation. This thinking introduces a best practice of assessing the glands of all patients during a routine slit lamp examination.
Multiple studies demonstrate the effects of MGD on gland function and structure.35,36,37,38,39 Although they are related, function cannot be inferred from structure until advanced stages of the disease.40,41 Gland function can be identified by means of diagnostic gland expression by digital or standardized expression. Gland structure can be identified by means of Transillumination and gland imaging.42,43,44,45,46,47,48,49,50
Treatments must facilitate the evacuation of gland contents to restore normal gland function. While adjunctive therapies may be necessary to treat other sequelae of MGD and dry eye, the primary treatment should be to treat the root cause, obstruction.
Given the chronic and progressive nature of MGD, it must monitored and managed for the life of the patient.51,52,53,54 Ideally, all patients should be screened for MGD by assessing gland function and structure at all routine examinations because all patients are at risk for MGD. Office treatments should be offered when appropriate and on a recurring basis.55