Dear Doctors: I am 72 years old and have started to have problems with dry eyes. It’s not all the time, but at some point each day, my eyes will suddenly get very dry. It’s even hard to blink. What causes that? Those lubricating drops help, but only for a little while.
Dear Reader: You are experiencing what is commonly known as dry eye syndrome, or dry eye disease. The medical term is (deep breath) keratoconjunctivitis sicca. It’s a daunting name for a common condition that affects one-fifth of all adults. An estimated 3 million new cases occur each year. Although dry eye syndrome can happen to anyone and at any age, it becomes more common as people grow older. After age 40, the risk of developing dry eye syndrome increases with each passing decade. The condition is also seen more often in women who have entered menopause.
The exposed surface of the eye is covered by a triple layer of liquid known as the tear film. The components are secreted by various glands and tissues, and each plays a role in lubricating, protecting and nourishing the tissues of the eye. The inner layer, made up of mucus, provides stability and lubrication. Mucus has antibacterial properties, so it also helps protect against infection. The middle layer, known as the aqueous layer, is made up primarily of water. It provides hydration and washes away contaminants. It also contains proteins that nourish the cornea and electrolytes that help manage surface tension. The topmost layer is made up of lipids that act as a seal to prevent evaporation.
If something goes wrong with any of the three layers of tear film, the ability to nourish, hydrate, lubricate and protect the eyeball can be compromised. This can occur due to changes that take place as we age, some autoimmune diseases, a side effect of some medications, and hormonal changes. Environmental factors such as a dry climate, dry air from a heat source, air pollution, wood smoke, allergens and too much screen time can also play a role.
The most common form of dry eye is a deficiency in the lipid layer of tear film. Known as evaporative dry eye, it allows the tears that keep the eyeball moist to dissipate more quickly than they can be replaced. Lubricating drops with lipid-based ingredients, which can thicken the outer layer of tear film, can ease symptoms of evaporative dry eye. When the watery layer of tear film is compromised, it is known as aqueous-deficient dry eye. This is less common than evaporative dry eye. In this case, drops labeled as “hypotonic” can improve tear volume and help restore moisture to the exposed surface of the eye. For more serious cases of dry eye, prescription medications may become necessary.
Redness is common in dry eye, but avoid drops that promise “redness relief.” Most contain vasoconstrictors, which narrow blood vessels and can worsen dry eye symptoms. When the condition is severe, see your doctor. Complications can include chronic inflammation, damage to the surface of the eye, being susceptible to infection, and even vision loss.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
