Tuesday, January 25, 2011

Dry eyes make your vision blurry, give your eyes a break!

How many of us wake up in the morning with a sensation of grit in your eyes or eyelids stuck together by mucous discharge?  How many feel like their eyes start watering the minute they sit down in front of their computer or read a book?  How many feel like their eyes burn and are fatigued at the end of the day causing blurry vision?  If you are not experiencing any of the symptoms above, you probably know someone who does!  The common thread here is DRY EYES.

Now, you may ask me "Doctor, why would I have dry eyes if my eyes water all the time?"  Well, the tears are not just a turn on the faucet type mechanism.  In order for our eyes to feel moist they need a balanced lake of elements that covers the exposed surface.  Imagine a nice shear butter lotion covering your hands on a cold windy winter day.  A healthy tear film would provide such a barrier against the elements like air conditionining, heat vents, air blowing in your car, and sunny and windy weather.

A healthy tear film is like a tiered red velvet cake.  The foundation layer is a layer of sugar coating the eye surface cells to make tears stick to the surface.  The middle layer is the liquid aqueous layer that is actually made by your tear gland in the outer corner of the eye and the surface layer is that shear butter layer that provides a moisture trap and prevents evaporative loss of tears.  Many tiny glands inside the lower and upper eyelids called meibomian glands make this top oily layer.  Their production is highly regulated by sex hormones such as estrogen and progesterone, surrounding inflammation due to chronic allergies or other eye diseases and diet. 

This sounds like a simple enough cocktail but as we get older the cells that make the "ingredients" become compromised due to chronic allergies, exposure to the outdoor elements and simple cell aging.  As our eyes sense the lack of protective cover, a signal is sent to the brain to stimulate only one type of tear layer - the aqueous.  The other two layers are not made "on demand" therefore the evaporative loss will lead to lack of tears despite a well functioning tear gland and watering eyes!

So we face the challenge of finding the perfect tear "magic potion”.  So many choices of artificial tears are available to us over the counter!  In the next post, I will review my winners and losers of the over the counter products that are within arm's reach at your local pharmacy's eye care aisle.  Meanwhile you can see your eye doctor to eliminate presence of chronic allergies and meibomian gland dysfunction. Stay tuned!