What is Dry Eye?
Dry eye is a chronic and progressive disease of the ocular surface that causes a wide variety of signs and symptoms. In the past, it was thought that dry eye was primarily due to a lack of watery tears produced by the lacrimal gland above the eye. In the last few years, the complexity of the tear film and ocular surface has become increasingly apparent.
Dry eye is now categorized into two distinct groups:
- Aqueous deficiency dry eye (keratoconjunctivitis sicca)
- Evaporative dry eye (Meibomian gland dysfunction)
Over 85% of dry eye is thought to be mainly evaporative in nature due to meibomian gland dysfunction (lipid producing glands in the lids). Meibomian gland dysfunction also occurs in conjunction with many cases of aqueous deficiency dry eye. Any imbalance can lead to dysfunction of the tear film.
Because the tears are so complex and structured, all tear components need to be in balance. Part of the balance and function is neurological control. Sensory inputs to the brain create a complex feedback loop that controls the production of all tear components and functions. Damage caused by infection (such as herpes infection of the eye) or surgery (such as LASIK) can lead to dry eye, in some cases severe.
As dry eye worsens, inflammation becomes a greater part of the disease profile. While many cases of dry eye are relatively mild, some may progress to cause severe damage to the ocular surface and loss of vision.
Symptoms of dry eye include:
- Blurry and/or fluctuating vision
- Excessive tearing
- Burning or stinging of the eyes
- Tired or fatigued eyes
- Gritty or foreign body sensation
- Watering and sensitivity while driving and participating in outdoor activities
- Irritation or pain
- Contact lens intolerance or reduced wearing time
- Reduced reading or near working time