What is dry eye syndrome?


Dry eye syndrome (or dry eyes) is a chronic reduction in the normal amount or quality of tears, causing insufficient lubrication of the eye.  It can cause mild to severe discomfort and damage to the tissues of the surface of the eye—the cornea and conjunctiva.

What are the symptoms of dry eye syndrome?

Symptoms of dry eye syndrome include:

  • Eye irritation and redness
  • A gritty or burning sensation to the eyes
  • A foreign body sensation – the feeling that something is in your eye
  • Blurred vision (that may clear with repeated blinking)
  • Sensitivity to light
  • Contact lens discomfort or intolerance

What causes dry eye syndrome?

The normal tear film of the eye has three components:


Most of our tear film is composed of a watery substance secreted by the lacrimal glands, located above and behind our upper eyelids.  This watery (or aqueous) component of our tears nourishes and cleans the cornea and other tissues on the front of the eye.


Oils secreted from meibomian glands (located at the margins of our eyelids) help keep our tears from evaporating too quickly.


Mucin is a mucous-like substance that is produced by cells in the conjunctiva and outer surface of the eye.  It helps tears spread more easily across the cornea.

A deficiency in the quantity or quality of any of these three components of the tear film can cause dry eye syndrome.

The most common cause of dry eye is a deficiency in the watery component of tears, also called aqueous tear deficiency (ATD).  Keratoconjunctivitis sicca (KCS) is the medical term used to describe dry eye syndrome resulting from ATD.

Who is at risk of dry eye syndrome?

Risk factors for dry eye syndrome include:

  • Age: Our tear glands produce fewer tears as we get older.  Many people begin to notice dry eye symptoms after age 40.
  • Gender: Women are more likely to have dry eyes than men due to hormonal changes that accompany menstruation, pregnancy, and menopause.
  • Contact lens wear: Soft contact lenses in particular can cause tears to evaporate more quickly.
  • Computer use: We blink our eyes less frequently when using a computer.  This increases tear evaporation.
  • Dehydration: Failure to drink enough fluids can lead to general dehydration and dry eye symptoms.
  • Alcohol and caffeine consumption: Both can lead to dehydration and dry eyes.
  • Environmental conditions: Exposure to smoke, wind, air pollution, air conditioning, and dry climates can cause eye irritation and dryness.  The partially recirculated air in airplane cabins is especially dry and irritating.
  • Medications: Many medications, including antihistamines, decongestants, oral contraceptives, blood pressure and ulcer medications, and antidepressants, can cause dry eye symptoms.
  • Health conditions: health problems that affect the body’s ability to produce tears include arthritis, diabetes, thyroid disease, asthma, and lupus.
  • Sleeping with eyes partially open:  Some people sleep with their eyes partially open, causing the eyes to be chronically dry.  

How common is dry eye syndrome?

Dry eye is a very common disorder that affects a significant percentage of the population, especially people over the age of 40.  Studies vary in their estimations of this percentage, but at least one survey suggests that approximately 20 percent of people in the United States suffer from dry eye syndrome.1 Some researchers believe 75 percent of the population over the age of 65 experiences dry eye symptoms.

How is dry eye syndrome diagnosed?

If you suspect you have dry eyes, you should make an appointment to see your eye doctor.  He or she will ask you a number of questions about your symptoms and health history and perform one or more diagnostic tests to determine if you have dry eye syndrome.

One common diagnostic test is called the Schirmer test. It is performed by placing a thin strip of filter paper under your lower eyelid. An anesthetic eye drop may or may not be used prior to positioning the paper strip. You will then be asked to keep your eyes closed for five minutes.  The amount of wetting of the paperstrip is then measured to determine how well your lacrimal glands can produce the aqueous component of your tears. 

Another common diagnostic test for dry eye is called the Tear Break-Up Test (TBUT). It is performed by placing a small amount of a fluorescent dye in your tear film. Your eye doctor will then examine your eyes with a blue light. The dye mixes with your tears and causes the tear film on your eyes to glow under the examination light. You will be asked to blink several times and then keep your eyes open as long as you can without blinking. Your doctor will measure how long it takes for dark spots to appear on your cornea, indicating that the tear film has broken up and the surface ofyour eye has become dry at those spots. A tear break-up time of less than 10 seconds suggests an unstable tear film and dry eyes.

Your eye doctor may perform other tests in place of (or in addition to) the Schirmer test and/or Tear Break-Up Time test to determine whether or not you have dry eye syndrome.


Dry eye syndrome is a chronic condition resulting from inadequate tear production or quality, causing discomfort and vision issues. Symptoms include eye irritation, redness, blurred vision, and more. Factors like age, gender, contact lens use, and medical conditions can increase the risk. It’s a common problem, especially in individuals over 40.

To diagnose dry eye syndrome, consult an eye doctor who can perform tests like the Schirmer and Tear Break-Up Tests. Early diagnosis and treatment are vital for managing this condition effectively.