Managing Meibomian Gland Dysfunction

BY WILLIAM TOWNSEND, O.D.
JULY 1997

Between 20 and 40 percent of patients undergoing routine eye examination have some degree of MGD, according to Pepose et al. (1996). The etiology of this condition and many of its accompanying symptoms differ from classic dry eye and can create problems for our patients, particularly contact lens wearers.

MEET THE MEIBOMIANS

The meibomian glands produce lipids that reduce aqueous layer evaporation and facilitate spreading of the ocular tear film. Normally, the oils produced by these glands are clear and flow freely from orifices located just anterior to the mucocutaneous junction.

Gilbard et al. (1989) showed that occlusion of meibomian gland orifices in rabbits resulted in a fourfold increase in tear film evaporation. Studies show that in humans, increased tear film evaporation increases tear osmolarity, which adversely affects corneal metabolism and healing. Increased tear film osmolarity also leads to increased desquamation of corneal epithelial cells, creating a potential site for bacterial invasion.

MGD RISK FACTORS

MGD is commonly linked with acne rosacea and blepharitis, as well as hordeolum and chalazion formation. The condition occurs most often in individuals between 40 and 60 years of age, but there is no gender preference. It is more prevalent in individuals of northern European descent. I've also noticed a high prevalence among smokers.

PROFILE OF AN MGD PATIENT

Patients with MGD may be asymptomatic, or they may complain of burning, irritation and foreign body sensation. These symptoms are most noticeable upon awakening and lessen as the day progresses. This is best explained by the gradual reduction in tear osmolarity with increased lacrimation throughout the day. Patients can have both MGD and classic dry eye, whereby symptoms are severe upon wakening as well as at the end of the day.

Patients with MGD show a reduction in the normal "piano key" pattern of meibomian glands seen through the tarsal conjunctiva. Slit lamp examination reveals thickening of the lids, especially at the margins. Hyperkeratinization of the lid margins with superficial neovascularization is also common. In more severe cases, the lid margins may be altered with retroplacement of the gland orifices. Expression of the glands may produce thickened, inspissated oil that may resemble toothpaste in more advanced cases.

Untreated MGD can result in total occlusion of the orifice and loss of function of individual glands, which can atrophy until they are no longer visible. Capping of the orifice with a thin layer of epithelium is another telltale sign of MGD.

THE MGD TREATMENT PLAN

When blepharitis is present, lid scrubs and topical antibiotics are the treatment of choice. Although some practitioners advocate baby shampoo and other agents for lid scrubs, I've found that patients are more compliant and have a better outcome when they use commercial preparations such as Eye Scrubs (CIBA Vision). Instruct the patient to scrub the lids and lid margins. This helps to remove keratinized epithelium that surrounds the orifices and probably contributes to the disease process. Prescribe antibiotics, such as bacitracin and Polysporin, that are active against gram positive organisms. Antibiotic ointments applied to the lid margins are preferable due to longer contact time.

Heat increases blood flow to the lid margins and melts the thickened meibomian secretions. Instruct patients to place a folded, moistened washcloth in a plastic bag and heat it in a microwave oven until the compress is as warm as possible without causing discomfort or burning (about 15 to 20 seconds). By eliminating evaporation, the bag keeps the compress hotter longer. Instruct patients to express their meibomian glands after applying heat to remove the contaminated lipids, beginning at the base of the glands and expressing them toward the orifice.

Oral tetracycline has been shown to alter the esterification of lipids, thus reducing their viscosity and reducing the occurrence of plugging. The initial dosage is 250mg four times a day for one week, reduced to a maintenance dosage of 250-500mg per day. In individuals who cannot tolerate tetracycline, doxycycline 100mg per day is an excellent alternative. Remember to avoid tetracycline in children younger than 13 years of age or in pregnant or nursing women. CLS