What is Dry Eye? Causes and Symptoms
Tearing is one of the most common symptoms of dry eye.
Dry eye syndrome, or keratoconjunctivits sicca, is extremely common and affects upwards of 300 million people worldwide. It is also the most common reason for a visit to your eye doctor.
There are many causes of dry eye and can affect both young and older patients, but the likelihood of developing this condition increases with age.
Symptoms of Dry Eye
With every blink, tears are spread across your eye. Your tears help fight infection, but also keep your cornea hydrated (moist), smooth and clear. If you have ever scratched your eye, you know that the cornea is very sensitive. It has lots of nerve endings making it one of the most sensitive tissues in the body.
Your cornea is also responsible for about ⅔ of the focusing power of your eye (this explains why laser vision correction is so effective).
This explains some of the more common symptoms: redness, blurry vision, sensitivity and pain.
Here is a list of the more common symptoms;
- Dry sensation
- Blurry vision
- Tired/Achy eyes
Normal Tear Film
Your tears actually form a 3 layered film across the surface of your eye. The 3 layers are;
Mucous (mucin) Layer – this layer allows the tears to spread evenly across your eye
Water (aqueous layer) – this is the middle layer, the actual “tear”
Oily Layer – the outermost or most superficial layer, prevents evaporation
The bottom layer, the mucin layer, is produced by special cells located in the conjunctiva, the clear outside coating of the eye. The mucin allows even spreading of the tears and also fights infection.
The lacrimal glands produce the actual tears. There is one lacrimal gland for each eye.
The oily layer is produced by the Meibomian glands. These are tiny glands found on the edge of your upper and lower eyelids. The oily secretions prevent tears from evaporating too fast.
What Causes Dry Eye
There are dozens of “causes” of this condition, but actually they all cause dry eye by only one of two mechanisms. Dry eye is caused by;
- Insufficient tear production
- Rapid evaporation
Think you have dry eye? Call us to make an appointment or email us!
We look forward to seeing you.
Gregory Scimeca, M.D.
Burlington County Eye Physicians
Eye Professionals, LLC
Eye Physicians and Surgeons of Bucks County