Dry eyes are a serious and growing concern for millions of individuals. The eye must be bathed in a continuous flow of a tear film that consists of several components. A healthy tear film contains lipids, aqueous, and mucin. The outer lipid layer prevents evaporation, keeping the inner layers intact. The aqueous component is a mixture of proteins, mucin and electrolytes. The mucin provides viscosity; enhancing the stability of the tear film. The mucin is in its highest concentration the deeper into the tear film one goes.
In dry eyes, there tends to be a lower concentration of proteins in many cases. The water soluble part of the mucin also tends to be in much lower concentrations as well. These deficiencies tend to promote inflammation, and degrade the stability of the eye. Electrolytes tend to increase in volume as well, which furthers the dry eye problem. Since dry eye symptoms can be varied, the condition is often under diagnosed.
According to the Achives of Ophthalmology 14.4% of Americans report dry eye symptoms, and that increases with age. 8.4% of people under 60 years of age report the discomfort of dry eyes, while 19% of folks older then that do. It is a progressive disease. Individuals that undergo Cataract and Refractive surgery report worsening symptoms, due to decreased corneal sensitivity. In addition, damage to the tear producing Goblet cells cause additional compromise in tear production and quality.
Diagnosis based on symptoms includes discomfort, dry, sandy feelings, burning, light sensitivity, and blurry vision. Important testing to confirm the disorder includes evaluation of the tear film and cornea with Lissamine green and Rose bengel, Fluorescein staining, Schirmer tests, tear meniscus and Corneal staining. The process is simple. Irritation triggers inflammation which is followed by tear deficiency and instability.
Therapeutic goals include increasing tear production, and the quality/components of the tear film. To that end, the first step is the use of artificial tears. They come in a variety of formulations starting with basic low viscosity drops, and extending to thicker Gel drops. The thicker the drop the better it covers the corneal surface. However the down side is that they also will blur the vision as they get thicker. In more severe cases Gels/ ointments are employed to keep the eye covered for a longer period of time. This enables the corneal surface to regenerate and heal.
In worse cases of dry eye, topical steroid drops are used. This reduces inflammation in the tear producing glands such as the Lacrimal Gland. Often they are used for up to 3 weeks in conjunction with the artificial tears. If further therapy is necessary, Restasis is used to increase tear production. This is essentially Cyclosporin which is an anti-autoimmune medication. It is affective, but must be used twice per day for at least 3-6 months, and often longer.
A new development in the treatment of dry eyes is better care of the eye lids. It has now been confirmed that lid inflammation, Blepharitis, reduces tear production and quality. As such, improving this important area has emerged as a focal point of treatment. A new antibiotic called Azasite is now used to kill lid bacteria, and clean out invasive organisms that inflame the lid margin. It is used twice a day for 2 days followed by once a day for a week. Many eye care providers also advise using it once a day for the first day of very month for 6 months. In doing so, it maintains good lid hygiene. Since dry eye is a chronic condition, therapy should be geared for the long haul.
In the most extreme case we now insert Puntal plugs into the lid ducts in an effort to keep all the tears in the lower lid area, increasing the tear meniscus. It has dramatically improved many symptoms, and helped heal the ailing corneas.
In summary, dry eyes are a common, and chronic condition that requires aggressive treatment in order to prevent long term damage to the eye, and improve patient comfort.