A Schirmer test is a simple procedure your eye doctor uses to help diagnose dry eye syndrome. It’s a painless test using specially calibrated blotter paper inserted into the lower eyelid. It’s left in place for several minutes and then removed for measurement.
By examining the paper, an eye care professional can determine if the eye’s tear content and flow are normal or not.
German ophthalmologist Dr. Otto Schirmer was intensely interested in lacrimation or tear flow and how it worked to maintain the health of the eye. A talented surgeon and physician who liked to think outside the box, Dr. Schirmer developed the Schirmer tear test, or STT just before the turn of the 20th century.
Before learning more about the Schirmer test, it’s important to first understand the function of tears in the human eye.
What do Tears Do?
The eye’s tears serve several important functions:
The eye has no blood vessels on its surface, so tears bring oxygen and nutrients to the cells there.
Tears moisturize the eye and wash out irritants and particles.
Lysozyme, an antibacterial compound found in tears, fights infection and prevents invasion by pathogens.
Tears contain a healing substance to promote eye health.
Did you know that tears even help us to see better? Yes, by creating a smooth surface, tears help to refract or direct light correctly, helping to form a clear image. Tears also have what is called tear stability, which refers to the amount of time they remain active on the surface of the eye.
The Composition of Tears
Tears may look simple, but they are not. They actually have two layers: A lipid layer and an aqueous one. Lipid means fat or oil-based; aqueous means water-based.
If you look closely at a few tears on your finger under a strong light, for example, you may actually be able to see a very thin, oily film on the top of the tears. This is the lipid part. It only makes up about 5 percent of the total tear composition, and the lipids’ main function is to give tears more stability and allow them to stay on the eye’s surface considerably longer than they would if they were just aqueous.
Tear lipids also give tears more thickness and lubricating ability than water alone would have. The lipid and the aqueous layers come from two different places in the eye and don’t mix together until they are secreted onto the eye’s surface.
The edges of the eyelids have what are called Melbomian glands. These provide the lipid tear layer. A major cause of dry eye occurs when these glands malfunction and produce a lipid that’s too thick.
This thick secretion turns waxy and blocks the glands, resulting in tears with way too little lipid content. This problem goes back to the concept of tear stability.
Without lipids, tears will lack stability and disappear way too fast. The aqueous layer alone cannot create enough stability, so the person experiences the symptoms of dry eye:
A gritty sensation of something in the eye, especially like sand
Sensitivity to light
Inability to tolerate contact lenses
Melbomian gland dysfunction is more common in older people.
Aqueous tears come from the underside of the upper eyelid and contain a substance called mucus mucin, a protein that helps with tear stability. Mucus mucin also helps to stabilize tears by allowing them to flow evenly and freely across the surface of the eye.
Mucin is a substance found throughout the body, where it typically plays a protective role in various organ systems. It forms part of and refers to the medical term mucus.
How is the Schirmer Test Performed?
The Schirmer test is only one of a number of dry eye evaluation techniques, but it gives a good amount of useful information, especially for such a simple test. To take the test, you only have to sit quietly and follow easy directions.
Schirmer test strips are made of a medical grade type of filter paper. They are designed for use in the eye, with measuring marks and rounded tips. Your doctor will place the strip into your eye on the lower lid so that part of the strip is in your eye and part of it hangs outside it.
The measuring marks are in millimeters. These marks will tell the doctor how much liquid the paper has absorbed. This information is converted into a figure that reveals whether your tear production is normal or not.
As your doctor inserts the strip, he or she will be careful to keep any skin oils off the strip because these could interfere with the test’s accuracy. The strip will remain in your lower lid for 5 minutes. After that, it’s removed and your tear output is measured.
What Does a Low Schirmer Test Mean?
Any result of 10 millimeters or more of tears showing on the strip after 5 minutes is considered normal. Anything less is indicative of a possible dry eye disorder. Both eyes will typically show similar results. Although the Schirmer test is not painful, your doctor will likely instill numbing drops into your eyes beforehand to minimize tearing due to irritation from the paper and to increase your comfort level.
A low Schirmer measurement means that your doctor will strongly suspect some sort of dry eye problem and take steps to further diagnose the exact cause and begin appropriate treatment.
Severe dry eye can be serious, causing abrasions to the cornea which are extremely painful and can potentially compromise your vision.
Autoimmune Dry Eye Disease
Some forms of dry eye are autoimmune. This means that the body has a problem with parts of the immune system that have become overactive and are attacking the body’s own normal tissue.
There are many forms of autoimmune disease that can affect many different parts of the body and not just the eye. Type 1 diabetes, SLE and rheumatoid arthritis are three examples of this.
If dry eye is caused by an autoimmune attack, the condition often responds very well to a drug called cyclosporine. Typically used to prevent organ rejection in transplant patients, cyclosporine helps to stop autoimmune dry eye at its source by modulating the inflammatory immune system response causing the problem.
When used for dry eye, cyclosporine is administered in special eye drops that aren’t absorbed into the main body systems and carry very little risk of the serious side effects that cyclosporine can otherwise cause.
At Top Eye Doctors Near Me Directory, your eye health is our top priority. Our members see many cases of dry eye and diagnose and treat the condition on a regular basis. If you’re concerned about dry eye or any other kind of eye or vision problem schedule an exam with one of our local providers. We warmly welcome all new patients.