Understanding Dry Eye Syndrome

The eye has many parts that must work perfectly for it to function smoothly. Apart from their close association with emotions, tears play the crucial role of constantly wetting the eyes.

This constant wetting nourishes the cornea, lubricates the eye's surface, and improves the quality of vision. Dry eye syndrome is a condition that impacts the function of the tears to perform this role, causing various symptoms.

What Is Dry Eye Syndrome?

Dry eye syndrome is a condition that affects the eye's ability to stay lubricated and can become quite uncomfortable. The tears in the eye comprise a film with three main layers, each critical to the entire film's function. To understand dry eye syndrome, you must understand the different roles of the tear film layers.

Base Layer

This lowermost layer that covers the eye surface helps ensure the entire tear film spreads evenly. It is a mucus layer produced by the white part of the eye and is usually very thin, providing anti-adhesive properties to the eye surface.

Middle Layer

This is the most voluminous of all the layers, and it is the one you see when you cry and what many people know as tears. The lacrimal glands produce it, mainly water, which contains nutrients that nourish the cornea. The watery or aqueous layer is also responsible for cleaning the eye surface when a foreign object gets in.

Top Layer

This is the protective layer of the tear film. It keeps the tear film from evaporating under the sun's heat. It is a lipid layer of the oil called meibum produced in the meibomian glands.

Types of Dry Eye Syndrome

Dry eye syndrome can occur in two primary forms, one being much more prevalent than the other. The two forms are unstable tears dry eye syndrome and insufficient tears dry eye syndrome. The main difference between the two forms lies in the root cause.

Unstable Tears Dry Eye Syndrome

This condition occurs when the tear film is poorly constituted, leading to faster evaporation and dry eye symptoms. This is why it is also known as evaporative dry eye, commonly a result of meibomian gland dysfunction. When the lipid layer is not of good quality or absent entirely, the issue usually lies in the meibomian glands.

Insufficient Tears Dry Eye Syndrome

This is the less prevalent form of the condition, and it occurs due to the lack of enough tears, which dissipate quickly. Also known as decreased tear dry eye syndrome, this condition occurs when the eyes do not produce enough watery layer. Without enough middle layer, the other two layers cannot sustain enough moisture for lubrication, leading to dry eye symptoms.