Tear Film

What is the Tear Film?

Upon blinking, a thin layer of tears (the tear film) should spread evenly over the eye. The tear film is actually composed of three separate layers:

1. The oily layer.

2. The watery layer.

3. The mucus layer.

Each layer is critical for a stable tear film and disruption of even one of the layers can lead to symptoms and dry eye. The oily layer is produced by the meibomian glands and helps prevent premature evaprotion of the tear film. The largest layer, the watery layer, is made up of what we typically think of as tears, which are produced by the lacrimal glands. The innermost layer, which is directly in contact with the cornea, is the mucus layer. This layer help the tear film adhere to the eye and helps the eye remain moist.

What are the symptoms of dry eye?

The usual symptoms of Dry Eye include:

1. Itching

2. Burning

3. Foreign body sensation or sandiness

4. Mucus discharge

5. Tearing

6. Difficulty wearing contact lenses

Patients often wonder how tearing can be a sign of dry eye. When the eye is irritated, it reflexively produces tears as a response to discomfort causing them to run over the cheek. These reflexive tears are not the same consistency as basal tears and as a result, do not remain in the eye as well.

What causes dry eye?

Tear production normally decreases as we age. Although it affects both sexes, dry eye is typically more prevalent in women, particularly after menopause. Sometimes medications may cause dry eye. Therefore, it is important to disclose all of the medications you are taking to your ophthalmologist.

How is dry eye diagnosed?

A thorough history reviewing all ocular and systemic symptoms, as well as an eye exam, will be adequate to diagnose dry eyes. During your exam, your ophthalmologist will place a variety of dyes in the eye to determine dry eye and its severity. Another test, known as the Schirmer’s Test, involves placing filter-paper strips under the lower eye lids to measure the rate of tear production.

How is dry eye treated?

Treatment of dry eye depends on its severity. Mild dry eye symptoms can be managed with over-the-counter artificial tears, which help lubricate the eyes and maintain their moisture. Not all artificial tears are the same, so it is important to discuss with your ophthalmologist the best type for you.

To help conserve more of your tears, your tear ducts, or puncta, may be closed off, temporarily or permanently. Puncta are the pathways of the tears’ drainage sytem. They are located on the inner edge of both eyelids. Using a material like collagen or silicone, a simple in-office procedure can be performed to plug these openings, conserving more of your natural tears. In some cases, an approach using cautery can be used to seal off your puncta permanently.

Mild inflammation of the eye is believed to play a role in either causing or worsening dry eye. Prescription medications, such as low-dose immunomodulators, may be used to treat this aspect of dry eye. For more severe cases of dry eye, topical hormone drops may be prescribed. Serum, the clear substance found in blood, can be drawn and also used to treat severe cases of dry eye.

Since tears evaporate like water, taking steps to prevent this evaporation is prudent. Use of a humidifier and wrap-around glasses can reduce the effect of evaporation. Take note of your environment, particularly where you work. For example, if your desk is immediately below a cooling vent or forced air duct, it may be wise to move your workspace so that it is not in the air’s direct path.

Certain supplements, such as omega-3 fatty acids, may aid in the production of the tear film and regulate dry eye symptoms. It is important to discuss with your ophthalmologist if this is appropriate alternative, along with what dose and at what frequency to take the medication.

Dry eyes are a common problem affecting many people. Fortunately, they are generally more of a nuisance than an indication of a more serious condition. While dry eye typically cannot be cured, there are a multitude of treatment options your ophthlamologist can prescribe to help alleviate your symptoms and improve your visual functioning.