If I have dry eye syndrome, how come my eyes are wet? What’s going on?
There is a great deal of misunderstanding about Dry Eye Syndrome. In fact, Dry Eye Syndrome (Keratoconjunctivitis sicca) can be caused by several different conditions but the most common cause is Meibomian Gland Dysfunction (MGD), a chronic abnormality of the meibomian glands. These are tiny glands in the eyelids that produce natural oils to stabilize the tear film. MGD may cause eye discomfort and tear film abnormalities leading to poorer visual function, faster tear evaporation, and damage to the surface of the eye.
Typical symptoms of Dry Eye Syndrome (DES) are dryness, itching, pain, redness, pressure, burning, and a sandy-gritty eye irritation that gets worse as the day goes on. It may feel like a speck of dirt is in the eye. The resultant damage to the eye’s surface increases discomfort and sensitivity to bright light. Both eyes are generally affected to varying degrees. Certain external conditions can aggravate dry eye symptoms, including pollen and allergies, dry air or wind, fans, dust or smoke, sitting too long at the computer, incomplete or insufficient blinking, and wearing contact lenses.
DES is a very common disorder of the tear film. Although the disease can be completely asymptomatic, Dry Eye sufferers often experience watering of the eyes, which is in fact a response to irritation caused by the tear film abnormality. Unlike naturally lubricating tears, these reflex tears will not necessarily make the eyes feel better. This is because they are the watery type of tears that are produced in response to injury, irritation, or emotion.
The tear film coating the eye, known as the precorneal film, has three distinct layers. The outer layer is the lipid layer that contains oils secreted by the meibomian glands from the eyelids. These lipids coat the other layers and provides a hydrophobic (not water permeable) barrier that envelops the inner two layers of tears and prevents evaporation. The middle layer, the aqueous layer, is mostly water with electrolytes and other nutrients and antibodies. The innermost layer is the mucous layer which coats the cornea.
A lack of meibomian gland oily secretion can mean the tears are not enveloped in the hydrophobic film coat, leading to tears evaporating and becoming unstable. Since the lipid oil coating is not protecting the integrity of the tear film, this leads to excessive evaporation of the tears and is considered to be the primary cause or a contributing factor of most cases of dry eye.
Not protected by their normal tears, your eyes become irritated and produce excessive reflex tears. However, because these are reflex tears that are the watery type designed to wash out irritants and have minimal and short term lubricating qualities, they do not help with the problem. Thus, dry eye syndrome often results in episodes of excessively wet eyes.
If the condition is left untreated or becomes severe, it can produce complications that may damage the front surface of your eyes, resulting in risk of infection and decreased and blurred vision. However, thanks to new technological development, living with DES and treating your dry eyes has become easy and enjoyable.