Dry Eye - What are the layers of the tear film?

When you blink, a film of tears spreads over the eye, making the surface of the eye smooth and clear. Without this tear film, good vision would not be possible.

Sometimes people don’t produce enough tears or the right quality of tears to keep their eyes healthy and comfortable. This condition is known as dry eye.

The tear film consists of three layers:

  • An oily layer;
  • A watery layer; and,
  • A layer of mucus.

Each layer has its own purpose. The oily layer, produced by the meibomian glands, forms the outermost surface of the tear film. Its main purpose is to smooth the tear surface and reduce evaporation of tears.

The middle watery layer makes up most of what we ordinarily think of as tears. This layer, produced by the lacrimal glands in the eyelids, cleanses the eye and washes away foreign particles or irritants.

The inner layer consists of mucus produced by the conjunctiva. Mucus allows the watery layer to spread evenly over the surface of the eye and helps the eye remain moist. Without mucus, tears would not stick to the eye.

Normally, the eye constantly bathes itself in tears. By producing tears at a slow and steady rate, the eye stays moist and comfortable.

The eye uses two different methods to produce tears. It can make tears at a slow, steady rate to maintain normal eye lubrication. It can also produce a lot of tears in response to eye irritation or emotion. When a foreign body or dryness irritates the eye, or when a person cries, excessive tearing occurs.

It may not sound logical that dry eye would cause excess tearing, but think of it as the eye’s response to discomfort. If the tears responsible for maintaining lubrication do not keep the eye wet enough, the eye becomes irritated. Eye irritation prompts the gland that makes tears (called the lacrimal gland) to release a large volume of tears, overwhelming the tear drainage system. These excess tears then overflow from your eye.

Select Language

English French German Italian Portuguese Russian Spanish

"My experience with Dr. Murphy was very pleasant and professional. She took time to explain the problems and remedies. I had cataracts in both eyes. The lenses were replaced with multi-focal ones. I am extremely happy with the outcome. The staff was courteous, helpful and professional." James H.

"I was always so afraid to have anything done to my eyes, but Dr. Murphy's calm and full explanations took away this fear." Joan K.

"It is so nice to have a doctor responsive to my needs.  Dr. Murphy did both my cataracts and the multifocal lens enables me to read the smallest print.  I highly recommend Dr. Murphy and her staff." Bill S.

Alma Murphy MD PC
Eye Physician & Surgeon
490 N Alvernon Way, Tucson, AZ 85711

(520) 323-1313   eyesaz.com