When discussing dry eye, we throw around terms such as meibomian gland dysfunction (MGD), osmolarity, evaporative, and inflammatory on a regular basis. These terms seem to have different meanings to different people. Take MGD, for instance. When we ask practitioners what MGD is, we get a host of answers ranging from plugged glands to goopy discharge.
According to the International Workshop on Meibomian Gland Dysfunction, the definition of MGD is as follows: “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,” (Nelson et al, 2011).
We can get behind that definition. However, clinically, how do we know whether a patient has passed over into dysfunction or not?
Set a New Standard
For us, we look to a 2008 study by Korb and Blackie in which they evaluated patients to find a correlation between meibomian glands yielding liquid secretions (MGYLS) and symptoms. Of significance in their study was that they utilized the Korb Meibomian Gland Evaluator (TearScience), which applies a standardized force of 1.25g/mm2, simulating the pressure of a deliberate forced blink. In the study, they discovered that patients began to notice symptoms when only six glands were functioning. The severity of their symptoms increased with fewer glands functioning.
In a poster presented at the most recent American Academy of Optometry meeting, we discovered that 78% of our dry eye patient base had six or fewer MGYLS (Kading and Young, 2016).
As such, we have started to evaluate all dry eye patients for the number of glands that are flowing. We feel that the diagnosis of MGD is best determined through the use of gland expression. And, as such, the resolution or success of treatment is best accomplished when the number of MGYLS is increased. It is only through the improvement in function that a true dysfunction can be alleviated.
Our protocol is to use a calibrated meibomian gland expressor along the lower lid margin (Figure 1) to express 15 of these glands (five temporal, five central, and five nasal). We count the number of MGYLS. If patients have nine or fewer glands functioning, then they need to be started on some level of treatment. (As stated previously, symptoms usually start at six MGYLS or less.) At our follow-up appointments, we again evaluate the glands to determine whether there has been an increase in the number of MGYLS to ensure that our treatment has been successful.
We have found calibrated meibomian gland expression to be our new normal for determining whether a patient has MGD. If you have not tried this diagnostic tool for dry eye, we encourage you to make it your new normal as well. CLS
For references, please visit www.clspectrum.com/references and click on document #257.