Dry Eyes
Posted on May 31, 2008
Filed Under Dry Eyes | 1 Comment
Dry eye is a common ailment that can occur after refractive surgery. Everyone knows that tears run from our eyes when we cry or when our eyes are irritated. But tears have a much more important everyday function. A film of tears, spread over the eye by a blink, makes the surface of the eye smooth and optically clear. Without our tear film, good vision would not be possible.
1. The Outer Oily Layer
There are three layers in the thin film of tears which coat the surface of the eye, an oily layer, a watery layer, and a layer of mucus. The outermost layer of the tear film is produced by small gland at the edge of the eyelid, called meibomian glands. The main purpose of this oily layer is to smooth the tear surface and reduce evaporation of tears.
2. The Middle Watery Layer
The middle layer, and largest of the three, makes up most of what we ordinarily think of as tears. This watery layer is produced by small glands scattered through the conjunctiva, which is the delicate membrane lining the inside of the eyelid and covering the eyeball, and by the major tear gland called the large lacrimal gland. This layer cleanses the eye and washes away foreign particles or irritants.
3. The Inner Mucus Layer
The innermost layer consists of mucus produced by other cells in the conjunctiva. This layer allows the watery layer to spread evenly over the surface of the eye and helps the eye to remain we. Without mucus, tears would not adhere to the eye.
What are the Different Kinds of Tears?
There are at least two kinds of tear: those that lubricate the eye and those that are produced as a “reaction” to irritation or emotion. Tears, which lubricate the eye, are produced around the clock. Excessive tears occur when a foreign body irritates the eye or when a person experiences extremes of emotion, as in crying.
What is Dry Eye?
Dry eye occurs when the eye can not produce enough tears to keep the eye wet and comfortable. Stinging, burning, scratchiness, stringy mucus, and excess irritation from smoke are usual symptoms. Problem with contact lenses can be cause by dry eyes and make it impossible to wear contact lenses at all. Surprisingly, increased tearing may be a symptom of dry eyes. If the basic tear secretion is below normal, excess tears are produced by the lacrimal gland in response to irritation. Even though the eye is basically dry, overflow tearing can occur, masking the dryness, which caused them in the first place.
What Causes Dry Eye?
Normally, tear production decreases with age. Dry eyes are more common in women, especially after the age of menopause, but can occur at any age in both men and women. Dry eye can also be associated with arthritis. In addition, the inside of the mouth may become dry due to inadequate production of saliva. Swallowing or eating food then becomes difficult. Patient with dry eyes, dry mouth, and arthritis are said to have Sjogren’s syndrome.
Drugs and medication can also cause dry eyes by reducing tear secretion. Since these medications are often necessary, the dry eye condition may have to be tolerated or treated with “artificial tears.” For a listing of drugs that can cause dry eyes, please refer to the last section of this brochure.
How is Dry Eye Diagnosed?
Often an eye care professional is able to diagnose dry eyes by simply examining the eyes. Sometimes tests, which measure tear production, may be necessary. One widely used test involves the placement of filter paper strips under the lower eyelids to measure the rate of tear production under various conditions.
What is the Treatment for Dry Eye?
Replacement with artificial tears is the basis of treatment. Artificial tears are available without a prescription and are used as eye drops to lubricate the eyes and replace the missing moisture. There are many brands of artificial tears on the market, may be used as often as necessary, only once or twice a day, or as often as several times an hour. Solid inserts that gradually release lubricants during the day are also beneficial to some patients.
Conserving the tears, which are naturally produced, is another approach to keeping the eye moist. Tears leave the eye through tear ducts in both eyelids and go down into the nose. These channels may be closed by your eye care professional to create a blockage which will keep the eyes moist for longer periods of time.
Preventing the evaporation of tears can also prove helpful. In winter, when the heat is turned on, a humidifier or a pan of water on the radiator may help add moisture to the air. Wrap-around glasses (illegal to wear while driving in some states) may cut down evaporation of eye moisture due to wind.
Anything that adds to dryness such as an overly warm room, hair dryers, windy days, or anything that adds an irritant to he air will make a person with dry eyes more uncomfortable. Smoking is especially bothersome.
Scratchiness that is bothersome on first opening the eyes in the morning can be treated by using an ointment at bedtime. This can cause temporary blurring of vision, so many people use the least amount necessary to provide relief. Ointments containing Vitamin A are currently under investigation as treatment for dry eye, and early results are encouraging.
Who Can Treat Dry Eye?
A person suffering from dry eye may only need over-the-counter artificial tears, but since extreme dryness can cause serious damage to the eye, an examination and diagnosis by your eye care professional is suggested.
What Drugs Can Cause Dry Eye?
The following drugs may cause dry eye. Brand names may be different from the generic or clinical names listed below:
| Acetophenazine | Diethazine | Methyldopa | Propranolol |
| Amitriptyline | Dimethendene | Methylthiouracil | Protriptyline |
| Antazoline | Diphenhydramine | Metoprolol | Pyrilamine |
| Atropine | Diphenylpyraline | Morphine | Scopolamine |
| Azatadine | Doxylamine | NitrousOxide | Tetrahydrocannabinol |
| Belladonna | Ether | Nortriptyline | THC |
| BetaBlockers | Ethopropazine | Opium | Thiethylperazine |
| Bromphreniramine | Fluphenazine | Oxprenolol | Thioproperazine |
| Carbinoxamine | Hashish | Perazine | Thiordazine |
| Carphenazine | Hexamethonium | Periciazizne | Thirporpazate |
| Chlorisondamine | Homatropine | Perphenazine | Trichloroethylene |
| Chlorpheniramine | Imipramine | Pheniramine | Trifluoperazine |
| Chlorpromazine | Isoretinoin | Piperacetazine | Trifupromazine |
| Clemastine | Marijuana | Practolol | Trimeprazine |
| Cyroheptadine | Mesoridazine | Prochlorperazine | Tripelennamine |
| Desipramine | Methdilazine | Promazine | Triprolidine |
| Dexbrompheniramine | Methotrimeprazine | Promethazine | |
| Dexchlorpheniramine | Metscopolamine | Propiomazine |
If you suffer from dry eye consult your ophthalmologist or your family physician to discuss treatment.
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