Chronic Dry Eye | HealthInfi

Overview

Chronic dry eye is an inflammatory disorder of tears and the surface of the eye, also called the ocular surface. It encompasses a group of disorders, which typically cause symptoms of dryness and overall eye discomfort. It may also cause stinging, burning, a gritty feeling or episodes of blurred vision.

The condition affects an estimated 5 percent to 30 percent of the population age 50 and older in the United States. In addition, tens of millions of Americans experience less severe symptoms of the disorder.

Chronic dry eye is one of the most common reasons people visit an eye health professional. It occurs most often in the elderly.

The exact cause of chronic dry eye is unknown. External factors may aggravate dry eye symptoms, including conditions common in many workplaces such as prolonged computer use and exposure to air conditioning, heating, dust and allergens.

But chronic dry eye should not be confused with eye allergies, an even more pervasive problem. Eye allergies are reactions to substances in the environment that can result in some of the same types of discomforts associated with eye dryness.

There are two major types of chronic dry eye: aqueous tear-deficient and evaporative. Both can cause your eyes to sting or burn, feel scratchy, become irritated and tear excessively.

Chronic dry eye most commonly occurs in both eyes but may affect one eye more than the other. People with dry eyes have difficulty wearing contact lenses. They also may develop mucus in or around their eyes. There can be pain and redness in the eye, a feeling of heavy eyelids or blurred, changing or decreased vision. People with more severe cases of dry eye often are also sensitive to light.

Although eye infections are more common in people with chronic dry eye, irreversible vision is rare. More commonly, people with dry eye have fluctuating vision and experience problems with tasks requiring visual concentration such as reading, using a computer and driving. Most people with dry eye find the condition to be an uncomfortable nuisance, with many characteristics of other “chronic pain” types of syndromes.

Understanding the Role of Tear Film

The tear film on your eyes actually consists of the following three major components:

• Lipid. The outer layer of the tear film is covered by an oily layer produced by meibomian glands in the lower and upper eyelids. This layer smoothes the eye’s surface and keeps tears from evaporating too fast and helps them stay on the eye.
• Aqueous. The aqueous component is a watery layer that is produced by the lacrimal glands. This layer makes up most of what we normally consider tears. It nourishes the cornea (the clear tissue of the outer protective layer of the eye that transmits light) and the conjunctiva (a thin, clear layer of tissue that covers the white outer surface of the eye). This tear layer also cleanses the eye and washes away foreign particles or irritants that are wrapped up by the other major component—mucin.
• Mucin. The goblet cells of the conjunctiva, as well as the surface cells of the cornea and the conjunctiva, produce this protective lubricant of tears. It helps spread the watery layer of tears across the eye to keep the eye wet, and it traps and wraps up foreign pathogens and debris so they do not damage the ocular surface.Read More