What is Dry Eye?

Woman using an eyedropper to drop eye drops into her eye

Dry eye is a very common problem that affects millions every day.  It occurs when the eye does not produce tears properly, or when the tears are not of the correct consistency and evaporate too quickly.

Primary forms of Dry Eye

The tear film is made up of three properties: oil, water and mucus. If there is an imbalance in these properties, then dry eye symptoms can occur. There are two primary forms of dry eye: aqueous deficient and evaporative.


In this type of dry eye, there is an insufficient amount of aqueous, or the water component of the tears; therefore, there are not enough tears to bathe the front surface. This type of dry eye can be a result of underlying systemic disease.


The oil, or lipid layer, of the tears helps to keep the water portion from evaporating. In those who suffer from this type of dry eye, their tears are evaporating at a faster rate than normal, leading to their dry eye symptoms. This type of dry eye is a result of a condition called Meibomian gland dysfunction, or MGD. There are small glands that line the upper and lower eyelids that are responsible for producing the oil and mucus layer of the tears. When we blink these glands release a small amount of oil and mucus into the tear film. Over time, the glands can become clogged and those materials do not reach the front surface of the eye and mix with the tear film. When this occurs, symptoms result.

Dry Eye Contributing Factors

Dry Eye can have multiple contributors such as:

  • Medications such as: antihistamines, nasal decongestants, tranquilizers, blood pressure medicines, birth control pills and antidepressants
  • Diseases of the glands in the eyelids, such as Meibomian Gland Dysfunction
  • Pregnancy or hormone replacement therapy (women)
  • Following refractive surgery such as LASIK
  • Allergies
  • Infrequent blinking, associated with staring at a computer or video screens
  • Immune system disorders such as Sjogren’s Syndrome, Lupus and Rheumatoid Arthritis
  • Thyroid disease when the eye protrudes forward, or after cosmetic surgery if the eyes are opened too widely