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So far eidauk has created 23 blog entries.

One-sided World; Bizarre Brain Injury

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. (more…)

By |2018-12-19T17:20:46-07:00May 14th, 2008|Makes you go hmm, Physiology|0 Comments

Ancient Illusions; It’s All Greek To Me

I recently watched a well-done documentary on the architectural marvel, the Parthenon. Feel free to watch the whole program on PBS’s website. If you do, you can skip this post, because I’ll paraphrase just a part of the documentary here that deals with illusions.

As you can see from a close look at this picture, the columns are made up of multiple stacked “drums.” Recently, while the Acropolis Restoration Project was attempting to rebuild the 46 columns, it was discovered that the drums had very slightly different diameters. This finding suggested that the columns were not straight, but were curved (wider at the bottom). In fact, very few of the parts of the temple had a straight line to it, even the foundation was “bowed.” (more…)

By |2018-12-19T17:20:46-07:00April 24th, 2008|Illusions|0 Comments

Visual Auto-Completion

Have you ever had the annoyance of typing away on your word processor and had it automatically “correct” something you knew was already correct? My favorite is when I type “i.e.” and it thinks I meant to type “I.e.” Your computer thinks it’s smarter than you are. I’d like to think I’m smarter than it.

Your brain also has a built-in auto-completion or auto-correction function. And just like your word processor it often auto-corrects correctly and sometimes not. Here’s an example when it guesses incorrectly.


By |2018-12-19T17:20:46-07:00April 7th, 2008|Illusions, Physiology|0 Comments

You Too Can Be Legally Blind for $5.99!

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.


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.

By |2018-12-19T17:20:46-07:00March 17th, 2008|Makes you go hmm|0 Comments

We See Only What We Want to See

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.

By |2018-12-19T17:20:46-07:00March 8th, 2008|Illusions, Makes you go hmm|0 Comments

Cell Phones and Driving

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.

By |2018-12-19T17:20:47-07:00February 4th, 2008|Makes you go hmm|0 Comments

Ordering Cheap Contact Lenses; Hazardous To Health

contacts.jpgMore than 30 million people wear contact lenses. Many of those wearers purchase their lenses through low-cost outlets, like online retailers (i.e. 1-800 Contacts) or discount brick and mortar clubs (i.e. Costco). However, a recent study indicates that bargain shopping may effect your eye health.

The medical journal Optometry: Journal of the American Optometric Association (JAOA) reports “The findings indicated that online and store purchasers . . . are less likely to adhere to healthy eye care practices, as recommended by their eye doctors.” “Those who bought contact lenses at their doctor’s office followed a number of FDA recommendations more so than those who bought contact lenses elsewhere.”

Other interesting findings were:

  • 86 percent of individuals who purchased their lenses from an eye doctor received a yearly comprehensive eye exam. But, only 76.5 percent of those individuals who purchased their lenses via the Internet saw an eye doctor on a routine basis.
  • 35 percent of online purchasers did not check that the prescription was correct.
  • Fifty-seven percent of individuals who purchased their lenses from an eye doctor went in for a follow-up appointment; as compared to only 29 percent of online purchasers.
  • The majority of consumers feel more confident purchasing their contact lenses from a familiar and reliable place such as their eye doctor or store rather than through the Internet.
  • 89 percent and 91 percent of respondents respectively said they felt confident purchasing contact lenses from their familiar, reliable eye doctor or store. That number decreased to 77 percent when surveying individuals who made a purchase via the Internet.

“Although buying contacts online can be more cost-effective and convenient, we strongly urge patients to understand that there are risks involved to wearing contact lenses,” said Dr. Sclafani, one of the researchers. “Because of this, it’s necessary that patients visit their eye doctor on a regular basis and communicate any recent visual changes and discomfort experienced as a result of contact lens wear.”

By |2015-08-27T09:52:13-06:00January 31st, 2008|Eye health|0 Comments

Why Do Women Have More Eye Diseases?

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.

By |2015-08-27T09:52:34-06:00January 10th, 2008|Eye health, Makes you go hmm|0 Comments

What’s Up With My Eyebrows?

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.
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: 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.


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.

By |2015-08-27T09:53:01-06:00December 28th, 2007|Makes you go hmm, Physiology|0 Comments
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