Dry eye syndrome (DES) is not a single disease, but encompasses a wide variety of conditions that affect the tissues of the surface of the eye and the tearfilm that covers them. It is estimated that approximately 7 million Americans have detectable and symptomatic DES, but it is difficult to calculate the true scope of this problem due to the lack of a widely accepted method of making this diagnosis.
Let’s start with a brief anatomy lesson. The tearfilm is the dynamic coating of the surface of the eye, which itself consists of the clear cornea and the conjunctiva and is composed of three layers. The outermost layer is composed of a
lipid substance that is secreted by oil glands located at the edge of the eyelid. The next layer of the tearfilm is a watery layer secreted by the lacrimal (tear) glands and its role is to hydrate the eye. The base layer of the tearfilm
is a mucin (sticky) substance that is made by the cells of the surface tissues. Each of these layers must be present for the eye to function normally. DES can affect one or more of the layers of the tearfilm, which increases the
difficulty of diagnosing and treating this family of problems.
Tear production decreases with age, which is the most common risk factor for developing DES.This occurs in both sexes, but the hormonal changes associated with menopause makes DES especially noticeable in women. Prolonged
reading, computer use, or TV viewing results in decreased tear production and a reduction in the blink rate. Disorders which affect the oil glands of the eyelids and face cause tears to evaporate too quickly, as can smoking, living in a dry
climate, outdoor activities, contact lens use, and the use of certain medications, especially “redness relieving” eyedrops.
The most common symptoms that I encounter are burning, a gritty or sandy feeling of “something in the eye”, intermittent blurring, crusting of the eyes upon awakening in the morning, and eyestrain or fatigue, especially towards the end of the day. Another very common symptom is watering. As the tearfilm dries out, this causes the eyelids to drag over the surface of the eye and stimulates the lacrimal glands to produce watery “reflex” tears (the same type of tears that we make when we cry or get something in our eye). These tears don’t stick well to the surface, but tend to spill out of the eyes and create watering. For this reason, DES must be adequately treated and the ocular surface must be healthy and smooth prior to changing a eyeglass prescription.
An eyecare professional can detect DES during a complete medical eye examination. The most common means of diagnosing DES is to place a drop of fluorescent dye into the eye and examine the eye under a blue light. This will
cause the dry areas of the eye surface to stand out as bright green spots on a dark background. It is also important to fully examine the eyes and eyelids for any other ophthalmic conditions that can influence the ocular surface. The newest method of diagnosing DES involves sampling the patient’s tears and measuring the concentration of salt, which is increased in DES.
The mainstay of DES treatment is the use of lubricant eye drops (“artificial tears”). Lubricant eyedrops or eye ointment is available with or without preservatives and can be used as needed throughout the day. Lubricant eye ointment is also available for nighttime use. Both types are available without a prescription. My only word of warning regarding over-thecounter eyedrops concerns antihistamine-based products that claim to “get the red out” or treat allergies. These products are harsh to the ocular surface and create inflammation and dryness, making DES worse. Recent studies have also shown that the use of an over-the-counter oral supplement that is rich in omega-3 fatty acids can be helpful in DES, particularly in patients who have disorders that affect the outer oil layer of the tearfilm.
Another treatment for DES is closure of the entrance to the tear drainage system, or punctum. These are small openings located near the inner edge of the eyelid, one each on both the upper and lower lid. These openings are responsible for draining tears away from the eye. If they are closed, the effect is the same as putting the stopper in a sink or bathtub; the tears stay on the surface of the eye longer and there is less disturbance of the tearfilm, especially in cases where not enough tears are being produced. The simplest and common way of closing the punctum is through the use of a soft silicone plug that fits snugly in this opening, dramatically reducing tear drainage.
The only prescription medication specifically approved by the FDA for the treatment of DES is Restasis ® (cyclosporine), which has been used in the United States for over 10 years. Restasis ® is generally well-tolerated and is often very effective in improving DES, but since it actually changes and remodels the ocular surface tissue, these beneficial results can often take months to occur.
As we have seen, DES is a complex problem with a number of potential solutions. New methods of both diagnosis and treatment are currently in development. I encourage any patient with these symptoms to contact an eyecare professional for a complete, personalized examination.
Andrew Mohammed, MD graduated from Virginia Commonwealth University with a Bachelor of Science in Biology (Summa cum laude). He completed his medical training and received his Medical Doctorate from the historic Medical College of Virginia. After a one year internship, he then went on to complete a three year residency in ophthalmology at the same institution. Dr. Mohammed then completed a year-long fellowship in glaucoma at the University of Pennsylvania’s prestigious Scheie Eye Institute. His area of emphasis is cataract surgery and in the medical and laser treatment of glaucoma. Dr. Mohammed was born and raised in the Washington, DC metropolitan area. He is now proud to call New Mexico his home. He enjoys travel, fine dining, and the study of ancient and military history, swimming, and exploring