THE DRY EYE SYNDROME:

DIAGNOSIS AND TREATMENT

by Frank J. Holly, Ph.D

 If your eyes itch, especially as the day wears on, if you have excess mucus discharge upon awakening, or if you suffer from burning, chronic redness, or foreign body sensation (as if you had invisible sand in your eyes), the chances are that you are one of the ten million Americans who suffer from some form of the dry eye syndrome. If we count those who exhibit only marginal symptoms, the number of people afflicted may surpass thirty million. The majority of these patients are middle aged or elderly women but the disease is not limited to them as men and youngsters are also seen in the clinic with such a condition. The causes can be multitudinous but the clinical signs are often the same.

The most common symptom seen in such cases is a varying degree of damage to the ocular surface, both the conjunctival and corneal surface. Especially in the past, the symptoms were often diagnosed as allergy or infection and, as a result, mistreated. Even today, many ophthalmologists and optometrists are unfamiliar with this condition that can be quite debilitating at its severe stages. The open eye is covered by a very thin layer of tears merely as deep as the diameter of a red blood cell. This tear layer is coated with a hundred-fold thinner lipid layer to protect the tear film. For good visual acuity and for the health of the supporting tissue this fluid film has to be stable and remain continuous between blinks. If the tear film ruptures prior to the next blink repeatedly or if the blink is incomplete, the sensitive surface of the cornea (the window and the most powerful refractive surface of the eye) becomes exposed to the atmosphere and eventually will be damaged. A poorly formed, unstable tear film could be due to insufficient tears, but, more often than not, the cause is poor wetting of the eye surface by the tears.

DIAGNOSIS

The common clinical sign for the various dry eye conditions is the vital staining of the ocular surface that often forms specific patterns. Traditionally, the vital dye employed for the diagnosis of keratoconjunctivitis sicca is Rose Bengal even though the dye is quite irritating, especially to dry, delicate eyes. Recently, another vital dye Lissamine green has become available that forms identical staining patterns on the eye surface but is not irritating and the staining can be distinguished better in red, inflamed eyes. Slit-lamp examination, assessment of tear meniscus, Schirmer test of lacrimation, the concentration of certain tear gland proteins such as lysozyme or lactoferrin, and tear film break-up time are other diagnostic methods that can be used to confirm the diagnosis of dry eye states.

TREATMENT

The mainstay of treatment of dry eye conditions is the instillation of a tear substitute in the eye several times a day. There are many such formulations (ophthalmic demulcents) on the market. These formulations bring some relief but few of them wet the affected eye surface completely and their oncotic pressure (due to their minimal colloid content) is too low to assist effectively in the healing of the damaged ocular surface. There are some proprietary ophthalmic demulcents that will be available in the Fall of 2001 that will do more than diminish temporarily the ocular discomfort associated with dry eye states. Dwelle® and Dakrina® are clinically shown by diminished vital staining to heal ocular surface damage. These two eye drops are similar in biophysical properties except Dakrina® also contains solubilized vitamin A palmitate as an antioxidant (see Vitamins and Polymers.... )

There is even a healthy alternative to popular ocular decongestant solutions that merely improve the appearance of an eye by constricting the surface blood vessels. That eye drop is called NutraTear® and, in addition to wetting polymers, it also contains vitamin B12 as an antioxidant (see also Vitamins and Polymers.... ) .

For more information on the dry eye syndrome,  read the original article by Dr. Holly:  Diagnosis and Treatment, an Update .

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