LASIK

The cornea is the front surface of the eye. Similar to windshield wipers eyelids spread tears across the cornea to yield a polished optical surface and hence better vision.

The Waterworld of the Eye:
Like a tap pumping out water, the tears are secreted by the lacrimal glands and accessory lacrimal glands. Luckily there is no bill to pay. The eye lids act as windshield wipers which spread the tears evenly across the cornea polishing the optical surface. Finally the tears go down the drain thru puncti (small openings in the lid margin) to the nasolacrimal duct and into the nose. That is why when you put drops in the eyes sometimes you get a funny taste in the mouth.

Importance of Tears:

The tears are a combination of aqueous, lipid and Meibomian gland secretions each of which must be in proper ratio and volume. The natural tears are also an important source of minerals enzymes and antimicrobial substances like the lysozymes. These various substances are important to protect the eye from infection by killing microbes on the surface of the eye. Natural tears also provide nourishment to the top layers of the cornea. When the body is not able to make enough tears to protect the surface of the eye, cells on the front part of the cornea become sick or even die leading to a variety of symptoms that affect both comfort and vision. Prolonged reading or computer work can often cause evaporation of the tear film. Dry eyes can also be caused by hormone changes, allergies, auto-immune disease, eye surgery, contact lens wear, eye infections and drugs such as oral antihistamines, anti-depressants or hormone replacement therapy. Environmental factors such as exposure to cigarette smoke or other chemicals can also lead to problems.