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 – 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 don’t 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 mechanisms. Reprinted From Optometric Management Magazine, February, 2002 Article written by Jeffrey P. Gilbard, M.D., N. Andover, Mass.
WHAT CAUSES CHRONIC EYE IRRITATION?
Patients have crusting irritation at the base of lashes without variation throughout the day– onset is insidious.
Patients complain of burning and irritation without variation throughout the day. Symptoms are equivalent throughout the day because overuse of topical medications promotes damage. You should suspect this condition in all those who use traditional artificial tears more than four times a day. People generally have a history of escalating tear use.
LACRIMAL DRAINAGE OBSTRUCTION
Patients often have symptoms of tearing with actual and demonstrable tear overflow. Patients with meibomian gland dysfunction may feel like their eyes are tearing, but these patients have frank epiphora (overtearing).
The primary symptom for this condition is itchy eyes. Patients’ eyes may also exhibit increased mucus production. Onset of this condition is commonly seasonal, and it may be associated with hay fever, asthma and eczema.
Patients’ eyes may burn upon awakening. Patients frequently have a history of lid surgery or thyroid eye disease.
SUPERIOR LIMBIC KERATOCONJUNCTIVITIS
Symptoms include burning and irritation without daily variation. Abrupt onset and remissions characterize this condition. Patients often have a history of thyroid dysfunction.
SUPERFICIAL PUNCTATE KERATITIS (THYGESON’S)
Patients with this condition experience insidious onset of photophobia, eye irritation and decreased vision. The condition is episodic and recurring.
DRY EYELID SKIN
Patients complain of “dry eyes.” This condition underscores the importance of accurate localization of symptoms.
TARSAL FOREIGN BODY
Patients experience a chronic sensation of having a foreign body in their eye. This sensation results from exogenous material or an exposed meibomian-gland derived conjunctival concretion (calcium deposit just beneath the conjunctiva that acts as a foreign body)
MUCOUS FISHING SYNDROME
Symptoms include chronic eye irritation, redness (particularly inferior) and increased mucus production. Patients who reach into their eye to remove mucus strands caused by conjunctival trauma (eye rubbing) initiate the condition. A vicious cycle can develop.
Patients may complain that their eyes feel “tired.” Careful questioning reveals that patients are experiencing an involuntary closure of the eyes, rather than eye irritation. Driving, reading and exposure to sunlight worsen symptoms.
NON-SPECIFIC OCULAR IRRITATION
Normal eyes, abnormal environment. Eye irritation in response to smoke would be a typical example.
NORMAL EYES WITH HYPOCHONDRIASIS
This condition is uncommon. A careful history that fails to mesh with the examination can provide the first clue to its presence.
An inflammation of the lids attributed to a common mite that inhabits the follicle of the lash, especially in the elderly. It has the potential to destroy the glandular cells, produce granulomas and plug meibomian glands. Symptoms include itching and burning, possible lid margin crusting and loss of lashes, along with the classic lash cuffing.
Reprinted from Optometric Management Magazine, February, 2002
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