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Visual Field

The visual field test is designed to see how well you see outside of the center part of your vision (peripheral vision).

When we test your vision on the basic eye chart it is only testing how well you see right in the center and gives us no idea if you can see out away from the center. Your peripheral vision is very important because it gives you the ability to move around your environment without running into things.

There are several diseases that can severely impact your peripheral vision while leaving central vision unaffected. Some people can have perfectly normal 20/20 central visual acuity and have almost complete loss of their peripheral vision.

The main culprits that can have a big impact on your peripheral vision long before your central vision are glaucoma, some retinal diseases such as retinal detachments or retinitis pigmentosa, and some neurological problems like brain tumors, strokes, pseudotumor cerebri and multiple sclerosis.  

Most visual field tests are now done on an automated machine that flashes lights in your peripheral vision while you stare straight ahead. The lights continue to get dimmer until you can no longer detect that they are there. The machine is trying to find the dimmest light you can see at each point in your peripheral vision that it is testing for.

Many patients get anxious when they take this test because everyone wants to do well on it. That sometimes results in people not staring straight ahead but trying to look around to find the lights in an effort to do better.

That just makes the test come out worse. The machine also makes some noise as it changes location of the test light. Some people start pressing the buzzer whenever they hear a noise. They think there must be a light they missed but the machine, several times during the test, makes noise and then doesn’t put a light on to specifically see if you are trying to cheat by hitting the buzzer on the noise rather that seeing the light. Don’t do those things - you are only cheating yourself and making it more difficult to figure out your problem.

Ocular Coherence Tomography (OCT)

The OCT really took hold in eye doctors' offices at the beginning of this century. It was the first time we were able to see anatomy and pathology inside the eye on a microscopic level without the use of any radiation.

It has been a great addition to our examination techniques and allowed us to see many causes of vision loss at a level of detail we could never have before.

The two biggest uses for OCT in optical health are diagnosing diseases of the retina, particularly the area of central vision called the macula, and for diseases of the optic nerve, the most common of which is glaucoma.

For retinal disease it has been extremely helpful in macular problems such as macular degeneration, the leading cause of blindness in the U.S., diabetic retinopathy, retinal vascular occlusions and retinal swelling from inflammation.

The OCT allows us to see the individual cellular levels of the retina and helps in diagnosing the exact level where the pathology is occurring. If you look into the eye at the retina and see some bleeding in the macula it is difficult to judge where that blood exists. Is it superficial in the retina and coming from the retinal circulation or is it deep in and coming from the choroidal circulation under the retina?

The difference between those two locations can have a significant impact on what disease is causing the problem and what the proper treatment is. The OCT is also very helpful in following the effect of treatment. If you are treating a bleeding or swelling problem in the retina, the OCT can track the degree of improvement with a level of detail that could never be matched by the human eye.

For glaucoma and other problems with the optic nerve, the OCT can very precisely measure the thickness of the nerve tissue as it passes through the optic nerve. The hallmark of glaucoma is progressive loss of nerve fibers in the optic nerve.  Being able to measure the nerve thickness down to the micron level is very helpful in both diagnosing and watching for progression of any optic nerve disease.

Fundus Photography

A picture is worth 1,000 words...

Fundus photography is just that, a regular picture of the inside of your eye. The pictures highlight the appearance of the macula and the optic nerve and record it for prosperity.

As eye doctors we make notes in the medical record of what we see when we look in the eye. The wording of anything that looks abnormal with the retina or optic nerve does vary somewhat from doctor to doctor. One of things we record is something called the cup to disk ratio (C:D) of the optic nerve. We express that ratio as a percentage. Normal is about 30% or .3. The range of normal is very wide and some “normal” eyes have a .1 cup and others can have a .7.

In glaucoma those percentages get larger over time as the person loses nerve tissue. So, if you were born with a .3 cup but in your 60’s you were found to have a .5 cup that would be a strong indicator that you might have glaucoma.  However, if you were born with a .5 cup and at 60 you still have a .5 cup then you don’t have glaucoma.  When you look at someone at 60 with a .5 cup it’s hard to be sure if this is normal for that person or did they progress from a .3 cup to a .5 cup.  If only I had a picture …  

Pictures of the back of the eye really do tell the story better than words. I can describe what the C:D looks like to me but a different doctor may describe it differently. Doctors are usually fairly consistent in their estimate of the C:D when it is the same doctor watching that C:D over time. When a different doctor estimates the C:D that consistency is just not there. My .4 C:D may be my partner’s .5. But you can’t argue with the picture.  

The same thing occurs with retinal bleeding. Rating the amount of bleeding as mild, moderate or severe is somewhat helpful but there is a broad range of “mild” or “moderate”. When comparing two pictures taken at two different points of time it is much easier to decide if something is really getting better or worse.

We also use fundus photography to keep an eye on small tumors that can develop in the eye called choroidal nevi. These are increased areas of pigmentation under the retina in an area called the choroid. Most eye doctors explain these pigmented spots a “freckles in the eye”.  Most choroidal nevi are small and fairly flat. They can, however, sometimes grow larger and rarely turn into a melanoma in the eye. Serial photographs are very helpful in watching the lesions for growth.

These three tests - visual field, OCT and fundus photography - make up the core of our testing. There are many other tests that can be performed along with your eye exam but these three we described here probably make up about 80% of the tests you may encounter, depending on your individual problem.

Article contributed by Dr. Brian Wnorowski, M.D.

Your Eyes Are A Precious Gift--Protect Them During The Holidays

“I want an official Red Ryder, carbine action, two-hundred shot range model air rifle!”

“No, you'll shoot your eye out.”

This line from “A Christmas Story” is one of the most memorable Christmas movie quotes ever. Funny in the movie, but the holiday season does present a real eye injury threat.

For those who celebrate Christmas, that risk begins even before the actual day.

Some of the most frequent holiday-related eye injuries come from the Christmas tree itself.

Holiday eye safety begins with the acquisition of the tree. If you are cutting down your own tree, please wear eye protection when doing the cutting--especially if you are going to be using a mechanical saw such as a chain saw or sawzall. You need to also be careful of your eyes when loading a tree on top of the car. It is easy to get poked in the eye when heaving the tree up over your head.

Once back at home, take care to make sure no one else is standing close to the tree if you had it wrapped and now need to cut the netting off. The tree branches often spring out suddenly once the netting is released.

Other injuries occur in the mounting and decorating phase. Sharp needles, pointy lights, and glass ornaments all pose significant eye injury risk. If you are spraying anything like artificial tree snow on the branches be sure to keep those chemicals out of your eyes.

Having now successfully trimmed the tree without injury, let’s move our holiday eye safety talk to the toys.

We want to spend the holiday happily exchanging gifts in front of a warm fire, drinking some eggnog, and snacking on cookies--not going to the emergency room with an injury.

The Consumer Product Safety Commission reported there were 254,200 toy-related emergency room visits in 2015, with 45% of those being injuries to the head and face--including the eyes.

In general, here are the recommendations from the American Academy of Ophthalmology in choosing eye-safe toys for gifts:

• “Avoid purchasing toys with sharp, protruding or projectile parts."
• “Make sure children have appropriate supervision when playing with potentially hazardous toys or games that could cause an eye injury."
• “Ensure that laser product labels include a statement that the device complies with 21 CFR (the Code of Federal Regulations) Subchapter J."
• “Along with sports equipment, give children the appropriate protective eyewear with polycarbonate lenses. Check with your eye doctor to learn about protective gear recommended for your child's sport."
• “Check labels for age recommendations and be sure to select gifts that are appropriate for a child's age and maturity."
• “Keep toys that are made for older children away from younger children."
• “If your child experiences an eye injury from a toy, seek immediate medical attention.”

More specifically, there is a yearly list of the most dangerous toys of the season put out by the people at W.A.T.C.H. (world against toys causing harm).

Here are their 10 worst toy nominees for 2018, with four on the list that are specifically there for potential eye injury risk.

Here are other toys to avoid:

• Guns that shoot ANY type of projectile. This includes toy guns that shoot lightweight, cushy darts.
• Water balloon launchers and water guns. Water balloons fired from a launcher can easily hit the eye with enough force to cause a serious eye injury. Water guns that generate a forceful stream of water can also cause significant injury, especially when shot from close range.
• Aerosol string. If it hits the eye it can cause chemical conjunctivitis, a painful irritation of the eye.
• Toy fishing poles. It is easy to poke the eyes of nearby children.
• Laser pointers and bright flashlights. The laser or other bright lights, if shined in the eyes for a long enough time, can cause permanent retinal damage.

There are plenty of great toys and games out there that pose much lower risk of injury so choose wisely, practice good Christmas eye safety, and have a great holiday season!

Article contributed by Dr. Brian Wnorowski, M.D.

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