welcome to disease section for dry eyes 

Tear film chemistry
Tear film chemistry

A tear film consists of outer lipid layer, intermediated aqueous layer and inner mucus layer. The outermost lipid layer contains low polarity lipid (wax, cholesterol esters) and high polarity lipid (triglycerides, phospholipids). It restricts overflow of tears and prevents evaporation. The middle layer constitutes the main portion of the tear film. This layer provides oxygen to corneal epithelium and washes the debris. The inner most mucus layer plays an essential role in stability of the tear film. It lubricates the ocular surface and protects against irritants. Dry eye syndrome is a condition when the quality of a normal tear film deteriorates by excessive tear evaporation which causes damage to the cornea.

Eye Anatomy
Eye Anatomy

The eye is our organ of sight. The eye includes cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous. Some common problems associated with eye vision are strain in eyes, red eyes, uveitis, anisocoria, blurry vision, night blindness, dry eyes, cataract, glaucoma, conjunctivitis, eyelid problems, corneal diseases, etc.

Tear film of the eyes
Tear film of the eyes

Our tear film is made up of three layers – an oil (lipid) layer, a water (aqueous) layer and a mucin layer. These three layers together help maintain the health of our eyes and prevent infection. When a person blinks, a film of tears spreads over the eye, making the surface of the eye smooth and clear. Without this tear film, good vision would not be possible. The function of the tear film is to protect and lubricate the eyes, reduce the risk of eye infection and wash away foreign particles.

A healthy eye vs a dry eye
A healthy eye vs a dry eye

Dry eye occurs when tears aren't able to provide adequate moisture. Symptoms include stinging or burning, episodes of excess tearing that follow periods of dryness, discharge, pain, and redness in eyes.

Lacrimal glands
Lacrimal glands

Lacrimal glands are almond-shaped glands, one for each eye, that secrete the aqueous layer of your tear film. They are situated in the upper lateral region of each orbit. In dry eyes syndrome, the lacrimal glands produce less of the lacrimal fluid.

Tear gland tissue
Tear gland tissue

The image illustrates tear gland tissue under the microscope 100x.