Dry eye syndrome, or keratoconjunctivitis sicca, affects approximately one out every five adults. This very common disorder is due to the improper quality or quantityof tear production by the eyes. In order for the eyes to see clearly, the surface of the eye must remain moist at all times. The surface of the eye is the only place in the entire body that requires this extreme level of lubrication, made necessary because it is exposed to the elements all day every day. Consequently, proper and healthy tear production is crucial to good vision and comfortable eyes.
The symptoms of dry eye syndrome include burning and stinging of the eyes. In severe instances dry eyes can cause significant pain. Redness, watering and even decreased vision can be due to dry eye syndrome as well.
In order to better understand dry eye syndrome, one must understand a little about normal tear production. Normal tears are not comprised of just water. They are made up of three components, each produced by a different part of the eyelid and the surrounding structures. The first component of tears is a watery and salty liquid called the aqueous layer. This component contains electrolytes and chemicals that nourish the eye. The second component is an oily layer called the lipid layer. The last component of tears is a mucous layer. All three components must exist in the right quality and quantity for the surface of the eye to remain healthy.
Dry Eye Syndrome
With dry eye syndrome, there is either decreased tear production of any or all of the three layers, or there is an increase in the evaporation of the tears, because the tear is not made up of the right combination of the three components. There are many reasons why the tear layer on the surface of the eye may become abnormal. However, by far the most common cause is due to a decrease in the oily component of the tears. The lipid layer is produced by tiny glands called meibomian glands located right on the edge of the eyelid, very close to the lashes. When these meibomian glands do not produce the right quality or quantity of lipid, it results in the most common form of dry eye syndrome. An abnormal quality or quantity of lipid production by these glands is caused by a variety of reasons: age, diet, stress, hormones, medications, skin type and genetics.
The oily lipid layer is responsible for preventing the watery aqueous layer and mucous layer from evaporating. This lipid layer acts as sort of a cover over the other two layers, allowing them to remain on the surface of the eye longer, before evaporating. When there is not enough lipid in the tear it evaporates too quickly. The lipid layer also moisturizes the eye, just like oily lip balm lubricates chapped lips. Placing water on chapped lips is not very helpful in moisturizing the surface of the lips. In the same way, water alone on the surface of the eye is not helpful unless it also contains the oily lipid layer.
When this very important lipid layer is not produced in the right quantity or quality, the eye becomes dry and the patient begins to experience the symptoms of dry eye syndrome.
The body then begins to overcompensate for this deficit of lipid by over producing watery aqueous.
This results in a state where the tears are extremely watery and may pour from the patient’s eyes.
This seems like a paradox- the eyes are dry yet they are overflowing with tears. Unfortunately, the tears that are being produced in this state are not of good quality, containing too much aqueous and very little lipid. This cycle continues to worsen unless treatment occurs.
There are many treatment options for dry eye syndrome, including: lid hygiene techniques, doxycycline, Restasis, prescription steroid eye drops, artificial tear products such as Refresh or Optive, punctual plugs and vitamin supplements such as omega fatty acids, vitamin E, and flaxseed oil. Your doctors at the Texas Vision & Laser Center will review with you which treatments will work best for you.