Contact lens intolerance

Feb 15, 2010

Recognition and treatment of meibomian gland dysfunction and dry eye disease are important in contact lens wearers because these common conditions are a frequent cause of lens intolerance.

Key Points

San Francisco-Recognition and treatment of meibomian gland dysfunction (MGD) and dry eye disease are important in contact lens wearers because these common conditions are a frequent cause of lens intolerance, said Gary N. Foulks, MD, at the annual meeting of the American Academy of Ophthalmology.

MGD and dry eye both affect tear film instability and can lead to ocular surface damage. They share several symptoms in common based on these similarities. Patient complaints with both MGD and dry eye disease include fluctuating vision, especially when reading or using a video display terminal, as well as irritation, foreign body sensation, itching, and burning.

"Whether dry eye begins as an evaporative or aqueous deficiency condition, compensatory mechanisms often result in the appearance of a hybrid phenotype of dry eye," Dr. Foulks said.

The diagnostic evaluation for MGD and dry eye includes tear break-up time measurement with fluorescein to determine tear film instability. An external examination for meibomian gland plugging, lid margin redness, and noting the characteristics of the meibomian gland secretions is the most important aspect of the evaluation for identifying MGD.

"In MGD there may be plugging of the gland orifices or turbid secretions that can advance to turbidity with clumps or the presence of a frank paste-like secretion," Dr. Foulks said. "With chronicity, there may be telangiectasia of the lid margin as well as cicatricial changes in the orifice and even notching or scarring of the lid if inflammation is significant."

Additional testing for diagnosing dry eye includes examination of the tear meniscus at the slit-lamp. Presence of a reduced inferior marginal tear strip is indicative of aqueous-deficient type of dry eye, and the appearance of mucous debris in the tear film represents a marker of inflammation. Tear production should be measured with a Schirmer or cotton thread test.

Staining studies to identify ocular surface damage should be performed whether dry eye or MGD is suspected and should include fluorescein to reveal corneal surface changes and rose bengal or lissamine green to determine conjunctival damage.

Intervention for MGD includes lid hygiene with hot compresses followed by lid massage, although this may not be sufficient as stand-alone treatment. Oral doxycycline may both provide antimicrobial activity and help to control inflammation by inhibiting lipase and matrix metalloproteinase activity. Topical corticosteroids and cyclosporine ophthalmic emulsion 0.05% (Restasis, Allergan) also may be used to control inflammation as needed, although these agents may not change the quality of the meibomian secretions.

Topical azithromycin ophthalmic solution 1% (AzaSite, Inspire Pharmaceuticals) also has emerged as an effective, off-label treatment. This macrolide antibiotic has both antimicrobial and anti-inflammatory effects and has been shown in clinical studies to have benefits for improving signs and symptoms of MGD as well as the abnormal lipid structure and function of the meibomian secretions, he said.

There also has been interest in oral essential fatty acids because of their anti-inflammatory effects. In a study by Pinna et al., oral therapy with linoleic and gamma-linoleic acid combined with lid hygiene was more effective in improving symptoms and reducing eyelid margin inflammation compared with either intervention alone. Macsai reported the results of a controlled study showing treatment with oral flaxseed oil improved signs and symptoms of MGD and had positive changes in the lipid content in red blood cells and meibum.

Ocular lubricants are a mainstay in the management of dry eye and there are a variety of products to choose from within the categories of hypo-osmotic, osmoprotective, surface protective, and lipid stabilizing agents. Anti-inflammatory treatment with cyclosporine A has been a valuable addition to the management of dry eye disease.

Preventive strategies are aimed at early recognition and disease control to prevent progression. These rely on counseling to make patients aware of environmental and other factors that may contribute to tear instability, and for those with MGD, reinforcing the importance of routine lid hygiene and massage.

FYI

Gary N. Foulks, MD
E-mail: gnfoul01@louisville.edu

Dr. Foulks is a paid consultant to Inspire Pharmaceuticals.