The function of your tears is to nourish, protect and lubricate the cornea of your eye and keep you comfortable. When the tear film becomes deficient in quantity and / or in quality, dry eye symptoms result.
About the Tear Film
The tear film is composed of three layers. The outer one is the oily layer which is produced by the meibomian glands located in the eyelids, it prevents the evaporation of the 2 other tear film layers and keeps the surface smooth. The middle layer is primarily made of water and is produced by the lacrimal gland located within the orbit above the lateral end of the eye, and helps to maintain the eye clean by washing foreign particles away. The inner layer is a mcucus layer produced by goblet cells from the conjunctiva, the clear tissue covering the white of your eye and the inside of your eyelids. This layer helps to spread the watery layer over the surface of the eye and makes tears stick to the eye.
There are two types of tears. Lubricating tears are produced continuously to keep your eyes moist and contain specific enzymes that protect from infection. Reflex tears are produced as a result of irritation from a foreign body or emotion (crying) or, paradoxically, from dryness itself in an attempt to keep your eye moist.
Dry Eye Symptoms
Symptoms include irritation, redness, itching, foreign body or gritty sensation, burning, reflex tearing and/or light sensitivity. Sometimes, you can experience blurry vision. There can be sloughing off of the superficial epithelial corneal cells making the corneal surface raw and this causes pain when the eye comes in contact with the inner aspect of the lid while blinking. You may also have decreased contact lens tolerance. Other associated symptoms include arthritis, seasonal allergies and dry mouth.
Causes of Dry Eye Syndrome
Dry eye is one of the most common eye conditions. The reason it is so common is that there are many causes of tear deficiency or dysfunction.
- Decrease in the tear flow due to aging.
- Hormonal changes in women due to menopause or pregnancy.
- Environmental factors such air conditioning, heat, smoke, pollution, dry climate and reduced blinking from prolonged computer use.
- Certain systemic medical conditions like Sjögren’s Syndrome, rheumatoid arthritis, lupus and thyroid disease.
- Certain eyelid disorders that affect normal eyelid function like Blepharitis, eyelids turning in or out, and Bell’s palsy.
- The use of some medications like diuretics for high blood pressure, beta blockers for high blood pressure and heart problems, antihistamines for allergies, sleeping pills, antidepressants and chemotherapy.
- Prolonged contact lens wear.
- History of Laser Vision Correction.
- The presence of Pinguecula or Pterygium.
- During the performing of tasks that require concentration like watching TV, computer use, driving or reading.
How is Dry Eye Diagnosed?
A slit lamp microscopic examination determines the status of your eyelids, the surface of your eye, the tear film and your blinking characteristics. Special tests can be conducted to determine the quality and the thickness of your tears as well as how quickly you produce tears.
Dry Eye Treatment Options
It is important to address the cause of dry eye whenever possible before considering treatment. Initial measures include the use of artificial tears for the watery layer and mineral oil drops for the oily layer.
Omega-3 fatty acids supplements and eating fatty fish such as salmon and sardines as well as flaxseeds help increase the density of the oily layer of the tear film.
The tears normally drain into the nose, throat and gastrointestinal tract via the tear ducts. The use of punctal plugs to block the tear ducts is a quick, painless, totally reversible and widely performed procedure. It keeps more tears available to your eye. This is effective in some cases.
A medication eye drop to increase the production of tears can also be used to treat dry eyes.