Contact Lens Practice Pearls
The Role of MGD in Lens Care
By Gregory J. Nixon, OD, FAAO
Contact lens discomfort is a frequent symptom among lens wearers. While a multitude of factors contribute to lens discomfort, first and foremost the ocular surface must be sound enough to support healthy contact lens wear. Therefore, it is necessary to highlight the recent work of the International Workshop on Meibomian Gland Dysfunction (MGD) in the May 2011 special issue of Investigative Ophthalmology & Vision Science (IOVS). This work was conducted by the Tear Film and Ocular Surface Society (tearfilm.org) under the direction of Kelly Nichols, OD, MPH, PhD, FAAO, Dipl PH, chair of the MGD Workshop Steering Committee.
The workshop conducted an evidence-based, comprehensive review of MGD to provide a contemporary understanding of the condition. The workshop reports represent a global consensus from more than 50 leading experts in the field that provides insight into the etiology and pathophysiology of MGD (Knop et al, 2011) and recommendations on defining and classifying MGD (Nelson et al, 2011). Of most interest to contact lens practitioners are recommendations on diagnostic methods and management guidelines highlighted below.
MGD Diagnosis and Staging
The complexities of differentiating MGD from other ocular surface diseases is highlighted in the diagnosis subcommittee report (Tomlinson et al, 2011). One of the key differentials is to determine whether evaporative dry eye results from aqueous deficiency or is MGD-related.
Clinical dry eye from both etiologies can result in decreased tear film breakup time, altered tear osmolarity, corneal and conjunctival staining, and adverse patient symptoms. Tests that can identify aqueous deficiency are reduced tear meniscus height or a positive Schirmer or phenol red thread test. When those tear volume tests are normal, MGD may be contributing to dry eye.
The most compelling part of the report details the evaluation of meibomian gland function and the staging of the dysfunction. It is recommended to assess meibomian gland expression by applying digital pressure over the central eight glands of the upper and lower lids. A four-level grading system has been established detailing the quantity of expressible glands in this region and the quality of the meibum secretion.
The treatment report (Geerling et al, 2011) details a hierarchy of management options based on the diagnostic grade level. First-line therapy includes eyelid hygiene with warming and gland expression followed by nonpreserved artificial lubricants.
Next, the first recommended pharmacological intervention is topical azithromycin followed by oral tetracyclines. The preferred oral formulations are doxycycline and minocycline due to their lipophilicity to penetrate into lid structures to enhance function.
In advanced stages, consider anti-inflammatory therapy. Topical steroids are recommended only as short-term remedies for exacerbations of acute inflammation. Chronic ocular surface inflammation can be addressed with topical cyclosporine, although there is some debate as to whether this treats MGD itself or concomitant aqueous deficiency.
Aiding Successful Lens Wear
Because dry eye symptoms are a leading contributor to contact lens dropout—and MGD may be a leading cause of dry eye—practitioners need to make a concerted effort to properly assess and manage MGD. Proper ongoing management of MGD can help reduce inflammation, stabilize the tear film and enhance the ability of the ocular surface to allow for successful and comfortable contact lens wear. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #188.
Dr. Nixon is an associate professor of clinical optometry and director of extern programs at The Ohio University College of Optometry. He is also in a group private practice in Westerville, Ohio. He is on the Allergan Academic Advisory Board and the B+L Advisory Board. You can reach him at firstname.lastname@example.org.