Thursday, May 27, 2010

Let's Talk About Tears!

Before we get to the topic of how to treat Dry Eye let's take a couple of minutes to learn about tears. We have two kinds of tears lubricating the front of our eyes. We have our reflex, or emotional tears. These tears are created by the lacrimal gland that sits up and above our eyes. The lacrimal gland  makes the tears that we cry when we watch a sad movie, or if something gets in our eye.

It's the tears that lubricate our eyes from minute to minute that we are more interested in when we are talking about dry eye. These tears are made by different types of microscopic glands on the surface of our eyes, as well as deep within our eyelids. These tiny glands can be affected by all kinds of medical problems like arthritis, lupus, and the hormonal changes that come with getting older.

Normal tears consist of three different, separate substances. We  have mucin which is created by the goblet cells on the front surface of our eyes. We also have a salt water or aqueous component created by the glands of moll and zeiss. Lastly, we have an oily substance called meibum which is created by the tiny glands that sit just inside our eyelashes on the upper and lower eyelids. These three substances are mixed together, kind of like Italian salad dressing, to form a lubricating layer between our eye and the air.

Shake up a bottle of salad dressing and let it sit for a minute or two. Notice how there is a little bit more oil on the top surface, a thicker middle layer that is a mixture of everything in the salad dressing, and then a layer on the bottom that is really thick. This is a good way to visualize our tears. We have more mucin close to the eye, a mixture or emulsion of mucin and aqueous in the thicker middle, and then a layer which is mostly oil sitting on the surface and preventing evaporation of our tears.

When our tears are healthy we have just the right amount, and we have just the right proportion of the three different components. We start to have problems with dry eye when we either have too few tears, or when the three components do not mix well. Next, we'll talk about the different types of dry. See you soon!

Tuesday, May 18, 2010

How We Diagnose Dry Eye

So you've come to Skyvision Centers with red, burning or tearing eyes. Your vision gets blurry when you look at a computer. You always feels like there's something in your eyes. How do we know it's from Dry Eye? How do we make the diagnosis?

Well, the very first thing we do is LISTEN to you! We try very hard to hear what it is that's bothering you. After that there are several tests that the technicians and doctors do to evaluate your tears, like examining your tears themselves. Both the doctors and the technicians look at your tears. Do you have a normal amount present just on viewing? Are they clear? Is there any debris, stuff like mucous or clumps of white blood cells present?

Before we put anything into your eyes we will often use a special instrument called an osmometer to check your tear OSMOLARITY, how salty your tears are. This is a very new, fully FDA approved test to evaluate whether you have a normal amount of salt in your tears. Normal is below 300 and abnormal is above 308, with the 300-308 range being relatively non-diagnostic. This test is very helpful in determining whether or not you have the most common type of Dry Eye, especially when other signs are hard to see.

The doctor will then put a vegetable-base dye called FLUORESCEIN into your tears to evaluate their function. How long does it take before they "break up"? Tears should remain smooth over the front of the eye for at least 8-10 seconds. Does any part of the front of the eye become stained by the flourescein? Dye staining is a sign that your tears do not work well enough. Finally, tiny strips of filter paper may be placed just inside your eyelids for a test of your tear production called a SCHIRMER test. This helps us know the volume of tear production.

That's how we do it! Lots of work to make the diagnosis, but're worth it! Tune in for lots of information on how we TREAT Dry Eye, coming soon.

Sunday, May 2, 2010

How Does The Eye Work?

How does the eye Work?

Over on our YouTube channel  we have a new series called "At the Dr. Whiteboard." Check it out! Pretty soon there'll be a video up that explains how our eyes work, and how it is that we actually see. Let's introduce that topic here and do a little review

Vision is kind of like filming a TV show. Our eyes act like the television camera, gathering images. The optic nerve works like the fiber optic cable that carries information from the television camera back to the computers in the production room. Those computers are very much like the back of our brain, the occipital cortex, where vision actually occurs.

So vision is actually a combination of three separate processes: focusing and capturing an image, changing that image into a series of electrical impulses that are then transmitted to the brain, and then processing those electrical impulses to re-create the image that we "see." Historically the majority of eye care has been dedicated to improving focusing, improving our ability to capture images. Cataract surgery, LASIK surgery, even something as simple as a pair of glasses allows us to create a sharp image.

Over time will talk a lot about these and other topics, as well as the exciting new vision processing programs like RevitalVision.