Chronic dry eye is a disease of the surface of the eye that can happen when your eye does not make enough tears or there is an issue with the tears that are made. Dry eye disease leads to symptoms that can make you feel miserable. Itchy, gritty, burning, and painful eyes are common in dry eye disease.
However, what may seem strange is that dry eyes do not necessarily mean little or no tears. Why is this the case? The answer lies in how the tears are made, what they are made up of, and the normal response to dry eyes.
The importance of the tear film
The reason the surface of your eye – the cornea – allows you to see is because of the tear film. The tear film is the perfect mix of oil on water, held onto the surface of the eye by mucus. Our tears are constantly washed over the eye with every blink. Without the moisturizing effect of tears on the eye surface, the cornea is not a polished lens. Instead, the cornea becomes rough and gritty like sandpaper.1
For someone with normal eye moisture, the corneal surface stays moist between blinks. This allows for easy, smooth blinking. In dry eye disease, the eye surface becomes dry between blinks. The rough corneal surface leads to blurry vision and the scratchy feeling that occurs with dry eyes. Blinking also happens less often in dry eye disease, making the condition worse.1
Increased tear production
In dry eye disease, the cornea does not have the moisture it needs. Blinking causes increased friction, which leads to irritation. The irritation triggers the eye’s lacrimal gland to produce more tears as a protective response to the dry, rough surface.2
The problem with this increased tear reflex is that the eyelids can only hold a certain amount of tears. The excess tears overflow out of the eye, causing tears to drain onto your face. Additionally, the lacrimal gland (tear gland) only produces the watery layer of the tear film and does not replace the oil and mucus layers that are also important parts of tears. So, even though your eyes are dry, the tear production and response is dysfunctional and does not solve your dry eye problem.2
Problems with the tear system
Any problem with the way tears are made can lead to dry eye disease or extra watering of the eyes. This may include problems with:3
- The glands that make the tears
- The openings where the tears flow out
- The ducts, or passageways, that the tears drain through
Are my watery eyes caused by chronic dry eye?
Watery eyes are not always due to dry eye disease. Many things can cause watery eyes. Any irritation of the eye surface can cause the eye to respond by producing extra tears.
Only a doctor can recommend the right treatment for your watery eyes. You may need special tests or exams, eye drops, or other treatments. Talk to your doctor about all the signs you have to make sure you get the right treatment for your symptoms.