Differentiating Meibomitis (Meibomian Dysfunction) from Dry Eye Syndrome
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Patients with dry eye, either from decreased tear production or increased evaporation of tears, most frequently complain of chronic sandy-gritty irritation in their eyes. Also, patients with dry eye typically note that their symptoms get worse as the day goes on. This is because eye closure during sleep forms a watertight seal over the tear film and gives the ocular surface a chance to recover. When the eyes open, evaporation begins, which increases tear-film osmolarity as the day goes on. If a person has these symptoms for more than 3 months and if the onset was gradual, the patient has dry eye unless the physician proves otherwise.
People with Meibomitis (known also as Posterior Blepharitis) also complain of chronic sandy-gritty eye irritation. But in these people, the irritation is worse upon awakening because the inflammation is in the eyelids. During sleep, tear production decreases, eye closure brings the inflamed lids right up against the eye, and the released inflammatory mediators act on the cornea all night, creating a symptom peak upon eye opening. When these people awake, tear flow increases, the lids pull away from the cornea, and their symptoms improve as the day goes on.
Eventually the chronic meibomian gland inflammation leads to meibomian gland dysfunction. When that happens, these patients develop a second peak in symptoms from dryness toward the end of the day. Finally, when the meibomian gland inflammation and secondary healing obliterate the meibomian glands, the morning symptoms resolve and patients are left with symptoms from dryness alone, with sandy-gritty irritation that gets worse as the day goes on.
Treatment of Meibomitis (Meibomian Dysfunction) and Dry Eye Syndrome
Many years ago, demulcents (polymers) were added to artificial tear solutions to improve their lubricant properties and change their viscosity. In 1975, a classic study demonstrated that demulcent solutions (all containing a preservative at the time) transiently increased tear-film stability in normal subjects. These solutions, whether of high or low viscosities, act by temporarily mimicking cell-surface glycoproteins, which are lost late in the disease. Solutions of higher viscosity remain in the eye longer. The effectiveness of preserved demulcent solutions hinges on their ability to temporarily stabilize the cornea-tear interface.
The next treatment advance Ã± preservative-free demulcent solutions- occurred about 15 years ago, shortly after researchers recognized that preservatives increase corneal desquamation. A recent study showed that traditional preservative-free demulcent solutions improve but donÃt normalize corneal barrier function in dry-eye patients. Improved corneal barrier function reflects decreased corneal epithelial desquamation and improved corneal cell junctions. Treatment with a preserved demulcent solution, while briefly increasing tear-film stability, actually diminished corneal barrier function. Preservative-free solutions established a new benchmark in artificial tear solution treatment.
Knowing what we know now about the mechanism and natural history of dry eye, we can anticipate that the next advance in treatment would address decreased conjunctival goblet cells, decreased corneal glycogen and elevated tear film osmolarity. Thera tears is the first eye drop shown in preclinical studies to restore conjunctival goblet-cell density and corneal glycogen with four-times-a-day dosing for 12 weeks. A preservative-free demulcent solution the product accomplishes this effect through two mechanismsReprinted From Optometric Management Magazine, February, 2002 Article written by Jeffrey P. Gilbard, M.D., N. Andover, Mass.