Dry eye syndrome is a condition where your eyes either don’t produce enough tears or don’t produce a sufficient quality of tears.
Three layers of liquid make up your tears. If any of the layers is lacking, your tears won’t keep your eyes moist and clean, leading to dry eye symptoms.
The outermost layer contains an oil, which keeps your tears smooth and prevents them from evaporating too quickly. The middle, and largest, layer of your tears is made up of water, which rinses your eyes and keeps them clean. The inner layer has mucus, which spreads the tears over your eyes and helps your tears stick to your eyes, keeping them moist.