What are Dry Eyes?
Do your eyes feel gritty or sandy, are they red and watery? You may be suffering from Dry Eyes. Dry Eyes occur when the eyes do not produce enough tears or when the quality of the tears is deficient, meaning the tears evaporate too quickly.
A normal tear film is comprised of three layers.
- An oily layer
- A watery layer
- A mucous layer
The oily layer is the outermost layer of our tears and is produced by meibomian glands which are located along the eyelid margins. The oily layer is essential in order to prevent the watery layer from evaporating too quickly. These meibomian glands can get blocked and the opening covered in oil. This leads to redness of the lid margins, irritation and can result in yellow spots forming on the lid margins. In response to the lack of oil, the remaining tears evaporate out of the eye more quickly, the eye surface starts to dry and the lacrimal gland (the gland responsible for producing the watery part of your tears) is stimulated to produce more and more tears. This often leads to an eye which “runs water”.
These watery tears have a higher salt content, which irritates/ inflames the surface of the eye. This irritation causes the eye to water more and the inflammatory cycle continues.
The watery layer is produced by lacrimal glands in the eyelid and makes up the main part of our tear layer. This part of our tears cleanses the eyes and washes away foreign bodies. If the lacrimal gland does not produce sufficient quantity of tears, this will result in a dry eye.
The mucous layer is the innermost layer of our tears and allows the tears to bind to the cornea and spread evenly over it throughout a blink. A deficiency in the mucin will result in the inability of our tears to adhere to the surface of the eyes.
A good quality tear film is essential for clear, crisp vision.