One-sided World; Bizarre Brain Injury

May 14, 2008

Imagine half of your world disappearing before your eyes in a split second. You wait for it to come back, but it never does. Everything you see is cut in half! I recently met a man that experienced this odd and rare brain condition.

This senior-aged man arrived in our practice in a wheelchair saying that he couldn’t see to his left. He had recently suffered a stroke in the right half of his brain and had lost complete function of his left arm and leg. After some testing, we discovered that indeed the entire left side of his vision was gone due to the stroke. This made sense since the right brain receives left side vision information.

However, I wasn’t expecting what he said next, “I have to turn my plate around to see the food on the other side.” You see, if just the left side of his vision is missing all he’d have to do is look a little more to his left to see the other side of the plate. I diagnosed him with hemispatial neglect (AKA left side neglect). He’s only aware of the right side of objects!

Patients with this condition will eat only the food on the right side of their plate, notice only the right side of a picture, and only draw the right side of a clock. This is an actual drawing from a hemispatial neglect patient. Some severe cases have even demonstrated the amazing ability to flip the neglect in their mind’s eye. For example, after being shown an upside-down picture of a face, the patient will mentally flip the picture right-side up and neglect the left side of the face!

We learn a lot about brain function by studying the devastating, but fascinating effects of brain damage. From neglect patients we’ve discovered that the right side of the brain is responsible for spatial interpretation. The eyes collect data about our environment, but the brain interprets and organizes it.

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You Too Can Be Legally Blind for $5.99!

March 17, 2008

Well, at least you can experience legal blindness for next to nothing. We’ll get to that in a minute.

The recent news of a legally blind man becoming governor of New York has the world rethinking the capabilities of the blind. To recap the media coverage, Lt. Gov. David A. Paterson took over the office of the morally-blind Eliot Spitzer. Governor Paterson, as reported by the New York Times, is totally blind in his left eye and legally-blind in his right eye. He is reported to have 20/400 vision, which means he can barely see objects from 20 feet away what the average person can see 400 feet away.

All the media coverage is also dispelling myths regarding legal blindness. In this blog post I want to do my professional duty to de-mystify and demonstrate legal blindness.

The United States Congress says that if a person still sees 20/200 vision, or worse, after glasses and/or contacts, then they are legally blind. It also states that if someone has only 20 degrees of peripheral vision, or less, they are also considered legally blind.

The misunderstanding occurs when the average person confuses “total blindness” with “legal blindness.” Let’s give some examples.

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As you can see, someone who is barely legally blind, as depicted above, is not even close to being totally blind. This explains why Gov. Paterson, with 20/400 vision, walks the hallways without assistance and can recognize faces at conversation distance. However, visual details and contrast are dramatically reduced, which limits these individuals in certain activities, such as driving and reading.

If you’ve ever wanted to experience 20/200 vision just visit your local pharmacy. Find a pair of reading glasses labeled with a power of +3.00 and put them on (that’s the $5.99 part), or if you already wear vision correction, put them on over your current glasses or contacts. Now look off in the distance. Instant 20/200 vision!

Want to try 20 degrees of peripheral vision? Fold a sheet of paper in half. Punch a half-hole in the middle of the crease with a standard hole punch so that when you unfold the paper you have a single circular hole. Now hold the paper about one inch away from your eye and look through the hole. Instant legal blindness!

In no way do I wish to diminish the severity of blindness. The achievements of these individuals is astounding, especially in a world that is designed for those of us with 20/20 vision.


We See Only What We Want to See

March 8, 2008

You may remember me talking about brain filtering; how our brain filters out what it doesn’t want to pay attention to. You could call it “selective sight”. For you married individuals out there, this is similar to “selective hearing” that plagues inattentive spouses. (I know I’m guilty of it.) I ran across some fun experiments that illustrate this phenomenon.

Simply put, the brain would get overloaded if it analyzed in detail everything we saw. Therefore, it ignores much of what the eyes see. Here’s a video I think you’ll find interesting.

The next video was shown to me in optometry school a few years ago. Play along and do the experiment yourself while watching the video. You’ll be amazed! Just click on this link. While watching the video, try to count the number of times the basketball is passed. Then watch it again, but this time just watch the video.


Cell Phones and Driving

February 4, 2008

cell-phone-driving_small.jpgOver 55% of the U.S. own cell phones. Given our love of convenience, we love our cell phones. Add that to our attraction to large shiny metal objects, we love our cars. It’s only logical that the average person drives and talks on their cell phone at the same time.

Ever pull up beside someone who’s using their cell phone in the next lane and wonder if you’re in danger? Apparently, some optometrists felt that way and did some research. In a recent article in Optometry: Journal of the American Optometric Association the question was asked, “Does cell phone conversation significantly affect the user’s peripheral vision?” I’ll save you from the long, boring story of how they setup the research and just give you the result. The article reports,

“Our research showed that the cognitive task involved in processing a conversation on a cell phone is reflected in a significantly reduced visual field area.”

Translation? Cell phone conversation detracts attention from the visual system. This means objects in a person’s peripheral vision are not noticed as readily. As you can imagine this is a major concern. The researchers even minimized the effects of dialing and holding the phone. So conversation in and of itself is the culprit. That means even hands-free devices won’t likely improve the peripheral vision issue.

In defense of those of us who do drive and talk at the same time, the researchers said, “More experienced drivers have an advantage, because driving becomes more of a subconscious task with increased driving experience.” For those of you who may be wondering, they also reported no significant difference between male and female peripheral vision decrease.


Why Do Women Have More Eye Diseases?

January 10, 2008

Within the past 20 years there has been a surge of research into women’s health issues. This movement was spurred by studies showing that women suffer from significantly more illnesses than men. Relating to the eye, women comprise more than two-thirds of the nation’s cases of blindness or visual impairment! Why does sickness favor women? Many doctors and researchers blame it on hormones. This is especially suspected with eye diseases. However, science still is uncertain how or why hormones influence women’s health.

woman-with-flower_small.jpgIt is well known that women suffer from dry eye problems much more than men. A very common cause of dry eye is inflammation in the eye tissues, and who do you think suffer more with inflammatory diseases? You guessed it, women. Lupus, rheumatoid arthritis, fibromyalgia, polymyalgia, and thyroid dysfunction are just a few diseases that cause inflammation in the body and result in eye dryness. Are hormones and inflammatory diseases related? The fact that the risk of dry eye (an inflammatory disease) skyrockets at post-menopausal age (marked by extreme hormone level changes in the body) makes me wonder.

Determining for sure if women have more eye illnesses is a difficult task for one main reason, women are more likely to seek medical attention. So do more women get cataract surgery because they are more prone to cataract formation or just because they go to the doctor more often? In my experience, men hold off as long as possible to seek professional help. Similar to not asking for directions until they are lovingly (or not) encouraged by their female counterpart.

Visit a wonderful website created by the Women’s Eye Health Task Force for more information.

EDIT (added March 26, 2008): Health News Digest has a very good article with statistics.


What’s Up With My Eyebrows?

December 28, 2007

The other day my four-year-old asked me out of the blue, “Dad, why do we have eyebrows?” I was baffled for two reasons: 1) that my son was so pensive and 2) that despite being an eye doctor, I didn’t have an immediate, scientific response. I replied how any baffled parent would and shot the ball to his court, “Why do you think we have eyebrows?” He replied after a brief pause, “So we don’t look funny.”

Reason #1

Eyebrows are one of those things that we take for granted until we have to do without them for a while. After doing some searching, I found many stories from individuals who, for one reason or another, had their eyebrows removed. Many said that liquids like sweat or rain would run right into their eyes. So that’s reason #1 for the existence of those furry things on our face. The arching shape and sideways hair growth direct liquids and debris away from the eyes.
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Reason #2

A less critical, but important social function is to aid in facial expression. Communication of emotions such as surprise, fear, and displeasure is executed with the eyebrows. If you’re interested in facial muscle anatomy and the expressions of each muscle, visit artnatomia.com to play with a simulator. The picture shows all superficial muscles that control facial and scalp movement. (Courtesy: http://www.medicalook.com)

EDIT (June 2, 2008): A recent U.S. study from the journal Plastic and Reconstructive Surgery indicates that eyebrow shape was deemed to be the greatest indicator of mood, drooping of the eyelids was considered the biggest indicator of tiredness, and raising the lower eyelid and the presence of crow’s feet were associated with happiness.

Unibrows

Those individuals with the fortune (or misfortune, depending on your perspective) of having one long, continuous eyebrow perhaps have the best eye protection. So think twice before you wax that unibrow into two brows. By the way, the fancy-schmancy scientific term for unibrow is synophrys.


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