Predisposing factors for Dry Eye

What makes a person’s eye dry? Are we destined to suffer from dry eyes or does modern technological society with rampant pollution induce it? Did our grandmothers suffer from it? Lets ponder on these frequently asked questions.

 Aging: As we revolve around the yellow sun we seem to loose all our strength and powers. Maybe if we were on krypton we would become stronger. On earth, every year production of fluids decrease. so we have aching joints and drier eyes

 Menopause : Need we say more? Hormones decrease affecting the functioning of the tear glands

 Allergy Response

 Environmental Stresses

 Contact Lens Wear: Is it sane to put foreign bodies in your eyes?

 Wind and Air Pollution: The megapolis with remnants of the industrial revolution, and craze for cars.

 Sunlight

 Ocular Surgery such as LASIK or Corneal Transplant. They transect the corneal nerves affecting reflex tear pathways.

 Medications / Topical Medications

 Preservatives in Artificial Tears

 Systemic Medicines- Antihypertensive, Antiandrogen, Anticholinergic, Antidepressant, Cardiac Antiarrhythmic drugs, Anti Parkinson’s

disease agents, Antihistamines

Figure 11.2 Dry Eye Disease: Predisposing Factors

Tears Definition of dry eyes

It is a mismatch between tear production and drainage. Either the drainage is excessive or the production is deficient. Usually the blame lies on inadequate production.

Tears are composed of three components – Lipid or oils, Aqueous or water and Mucin. Oil normally floats on water. Mucin layer helps keep the oily layer mixed with watery layer. There are also minerals, lysozymes and antibodies. Minerals are important for the nutrition of the cornea. Lysozymes and antibodies are the natural defense mechanism. The proportion and interaction of these three components is as important as the total volume.

Each layer of tear is produced by a different part of the eye. The water is secreted by the main lacrimal and accessory lacrimal glands. The former is located behind the outer part of the upper lid. The helper lacrimal glands are smaller and are in the lids. The meibomian glands produce the oily layer. They are present near the root of eyelashes and they pour their oil out from openings just behind the eye lashes. Numerous small goblet cells are embedded on the membrane lining the inner surface of the lids adding to the tear film.

The tears are spread across the front surface of the eye by the blinking action of the lids. The eyelids blink around 16 times per minute. The upper lid acts as a windshield wiper. With each blink it mixes the tears and coats the cornea with this thin protective layer. In a few seconds this film breaks up, to be restored with the next blink.