How We Recognize What We See

The mechanism that efficiently integrates visual signals in the brain is attention. Confronted by an image that contains multiple objects, movement and colors, the brain experiences difficulty attempting to simultaneously keep track of such a varied perception. So, according to research, the brain quickly draws up a rudimentary map of the image and picks out the more visually interesting aspects of the scene. As soon as the brain determines if the scene includes a particularly familiar object or motion, it begins processing the information by directing its attention towards the more stimulating phenomena that is creating the scene.

Recognizing Gestures

Through vision and perception, we learn to recognize gestures such as waving, extending the hand for the purpose of shaking hands and finger pointing. Since the most commonly used gestures are performed in the same manner (with minor variations), gesturing patterns that appear on the retina consistently and without dramatic alterations are recognized by the brain as a familiar “object” that has previously been perceived and encoded in memory. Consequently, by learning to correlate consecutive movements with the physicality of the object in motion (the hands, in the case of gestures), we learn to associate meanings with gestures regardless of the angle, distance or lighting conditions potentially influencing the perception of the gestures.

Facial Recognition

Gesture recognition differs from facial recognition because neurons in the brain’s temporal lobe “memorize” and respond to the unique features comprising each individual face. This information is further supported by the effects of a disorder called prosopagnosia has on people who experience temporal lobe damage. Although all other cognitive process remains intact, people with prosopagnosia cannot identify the faces of friends or family. Additionally, brain scans have revealed that when someone is shown one face and later, the same face with minor changes (like the addition of a moustache), temporal neurons are not as active as they are when confronted with the original, unchanged face.

Gesture Recognition and Computer Science Technology

Smartphone developers are currently incorporating gesture recognition technology in their devices for the purpose of defining and interpreting gestures through complex mathematical algorithms. Because most gestures are hand and face oriented, the ability to allow users to operate their smartphones by implementing computer vision concepts, special cameras and the vision/brain process template is rapidly becoming a reality. Gesture recognition technology is also helpful for people who are legally blind or physically handicapped. For example, sign language recognition software enables transcription of sign language symbols (gestures) into text.

The Importance of Healthy Eyes and Vision

Without good visual acuity, images that reach the brain do not accurately represent what we think we perceive. Abnormal visual acuity, i.e., when it is less than 20/20, and refractive errors can lead to learning problems, difficulty in judging dimensional space and memory confusion. When the eyes are damaged enough that they feed the brain with indistinct images and movements, misinterpretations often occur that can lead to unnecessary confusion, aggravation and potentially, accidents involving injury.

Spatial Relation Disorder

A spatial relation disorder is a type of visual processing disorder; it deals with difficulties in properly interpreting or understanding information received from the eyes. Individuals who have a spatial relation disorder find it difficult to distinguish objects’ relationships with other objects. This inability drastically interferes with learning subjects where letters and numbers are heavily used; math and reading, of course, would be two of the most common such examples.

The problem lies in a person’s ability to distinguish signs and symbols where the shapes are similar, but not the same. Here is such an example: (b/d) (p/q). To a normal person, the letters are distinguishable, but to a person with a spatial relation disorder, these letters become co-mingled in their processing. The same problem applies to numbers and math symbols, such as =, +, – and /. Additionally, to the average person, the number 14 is seen as a single number, but to a person with a spatial relation disorder number 14 may be seen as two separate numbers: 1 and 4.

Visual Discrimination

Visual discrimination disorders can also be categorized as visual processing disorders, just like spatial relation disorders. Visual discrimination between objects and their unique characteristics can be very confusing for people with this type of visual perception disorder.

Most people identify objects by such characteristics as color, shape, size and pattern, as well as by contrast. Individuals with this type of visual perception disorder, however, are restricted in their ability to recognize and comprehend these differences, making the learning process extremely difficult. After all, memory is a critical component of learning, and if there are inconsistencies in the visual recognition process then learning can become frustrating and difficult for the person involved – especially if the cause is not properly diagnosed.

Irlen Syndrome

Irlen Syndrome is another form of visual perception disorder that can make it difficult for a person to process text. This difficulty in reading text generally comes into play under certain conditions – most commonly when the text is written on a light background and the room in which it is being read is brightly lit. Under these conditions, the text can appear fuzzy and blurred. Many doctors recommend that individuals who suffer from Irlen Syndrome wear colored lenses, which simulate a low-light situation and improve the contrast between the text and background.

Signs and Symptoms

The potential inconvenience of a visual perception disorder is clear. Determining the presence of such a disorder, however, can often be challenging. Common indications that a person might be suffering from a visual perception disorder could include difficulty in spelling, limitations in visual memory, frequent mistakes in copying, a poor sense of direction and challenges with problem solving.

These traits can often be confused with those of a person with attention deficit hyperactivity disorder (ADHD), so you should rely on a qualified medical professional for a proper diagnosis.

Testing

A variety of tests are available to help determine if a person has a visual perception disorder. These tests are generally administered by an occupational therapist or a behavioral optometrist.

The most common varieties include the Test of Visual Perceptual Skills (TVPS),
the Test of Visual-Motor Integration (VMI) and the Motor-Free Visual Perceptual Test (MVPT). Each test can take anywhere from 30 to 60 minutes to complete. Of course, visual perception disorders are not an “all or nothing” issue. There are varying degrees of each disorder; proper testing is simply a way to ascertain to what degree a person is impacted.

Discovering that someone does suffer some type of visual perception disorder does not mean that they will be handicapped in certain areas for their entire life. Depending on the type and severity of the disorder, a variety of therapies and treatments are available to help the person deal with the condition. With proper detection and management, a visual perception disorder could be nothing more than a challenge to overcome.

The Big “E”

While you may think the white chart with the big “E” at the top is comical, it’s scientifically designed to determine your vision as compared to others. The United States has determined that the “average” person can see the chart when standing twenty feet away, hence the term 20/20 vision. This means that when you have 20/40 vision, you can see what the “average” human sees at twenty feet when you stand forty feet from the chart. In the United States, the legal cutoff for blindness is 20/200.

If you’re thinking that there’s no way your chair in the doctor’s office is twenty feet from the white chart, you’re probably correct. Some doctor’s offices use mirrors to simulate the twenty-foot distance, which still allows the test to be done properly.

The chart, also known as the Snellen chart, usually has each row of letters numbered. The top, the big “E” that the chart is known for, reflects 20/200 vision. While the big “E” may seem comically large to you, there are people who can see that letter from the same distance as you, but barely be able to detect it.

Likewise, the fourth line is reflective of 20/20 vision. The lines below that reflect 20/15, 20/10, and 20/5 vision, although humans rarely have 20/10 vision. Animals such as hawks are known for their acute vision—right around 20/5.

Other Options

Not everyone is able to take the Snellen vision test: if you have a disability or a shy child, you may use the “Tumbling E” chart instead. In this modification of the Snellen test, the “E” at the top of the chart is rotated in increments of ninety degrees. The person receiving this test will be instructed to demonstrate the direction the “E” is facing with their fingers by point up, down, right, or left. The size of the “E,” as well as the numbered lines, is modeled after the Snellen test.

If you’re near-sighted, your eye doctor will use the Jaeger eye chart to determine the degree of your near vision. In this test, a small hand-held card with various sizes of text is used, along with a scale ranging from J1 to J11. In this test, J2 type is equivalent to 20/20 vision.

Too Good To Be True?

If you want to test your vision without going to an eye doctor, there are several options for eye tests done at home. The internet hosts many different eye chart simulations which only require you to measure out the proper distance.

Online tests are a good way to get an idea of your vision, although they should not be considered an official exam. While the eye chart is a vital part of an eye exam, this only measures the degree of your vision acuity. This doesn’t test your peripheral vision, depth perception, eye fluid pressure, or how healthy your retinas are.  An eye chart exam primarily functions to determine whether prescription eyeglasses or contact lenses are a viable option to correcting your vision impairment.

But some of the answers to common and confounding questions are actually found within our eyes. For instance, why does your nose run when you cry? Do babies see differently? Why do we blink?

Here are a few of the most puzzling questions, answered:

1. Why do we blink? The human eye, on average, blinks over 4 milliontimes a year. But why? The typical function of blinking is to clean and moisten the eye: every time your eyelids close, they’re pushing salty secretions from your tear glands over the surface of your eyes, which flush away dust particles and lubricate the eye. Blinking is your main defense against developing eyesight problems.
   • On average, we blink every 4 to 6 seconds, but that can vary depending on the environment. If you are standing in a smoke-filled room, for example, your blinking will increase as your eyes attempt to stay clean.
   • Your emotional state matters, too: there’s a reason infants blink about once per minute, compared to the average adults’ ten to fifteen times per minute. When you read interesting material, or when you attempt to process a larger amount of information, you blink less: the eye is busy taking in information, which results in a longer delay between blinks. Likewise, if you’re sleepy, your eyes will try to close: the eyelid will stay closed for a longer duration than normal, and you will blink more.
   • Studies reported by NBC News revealed that during the Watergate hearings, eyes could tell it all: President Nixon’s blink-rate increased dramatically for questions he wasn’t prepared to answer.

2. Why am I tearing up? It’s common knowledge that your eyes, nose, and throat are all inter-connected; that explains a lot of what happens when you cry. Crying is typically an emotional response: happy, sad, angry, awe-struck… whatever the emotion, you cry it out. Most instances of crying may have you thinking of newborns, and rightly so. But did you know they don’t’ actually produce tears until six to eight weeks old? That’s also why there’s no messy snot to clean up from their tears: your nose runs because the tear ducts are draining into your nasal cavity, pushing whatever is in your nose out. However, no studies have ever proven that crying brings relief: it’s still a purely biological and sociological act.

3. Do men and women really see the world differently? Several studies by Brooklyn and Hunter colleges have revealed that your eyes may be different, based solely on your gender. These differences can be tracked to specific sets of thalamic neurons in the brain’s primary visual cortex.  For instance, male eyes are more sensitive to small details and moving objects—perhaps due to their hunters’ instincts. Female eyes are more perceptive to changes in color, which lines up with research that they are more sensitive to sounds and smells as well. So there is a reason she’s telling you the baby’s room is eggplant and not purple: her eyes actually detect a difference.

• But that’s not all: focus is also slightly different across genders. Studies at the University of Southern California reveal that men will focus on a person’s mouth during conversation, and are more likely to be distracted by their surroundings, while women shift their focus between a person’s eyes and body during conversation, and may be distracted by other people as opposed to any movement.

4. Why can’t I tell blue from green? You may have heard of 50 Shades of Grey, but what about 500? That’s how many different shades your eye can distinguish between, on average. Rod cells, one of two types of photoreceptors in your brain, are completely colorblind but allow you to see at night. The next time you’re up on a moonlit night, look around: your rod cells are letting you see shapes, but colors are more difficult to detect. Being color blind is attributed to your second set of photoreceptors, cone cells, lacking their color-sensitive pigments. Color blindness, while more common in men than women, is universal at birth. That’s right, Fido isn’t the only one that can’t see color: infants can’t distinguish between colors until around 2 months old. Color blindness in adults, a common eyesight problem, is genetic and present from birth: if you can’t tell red from orange, it’s all from mom and dad.

While there is still so much to eye care that remains a mystery, what we do know is allowing us to make leaps and bounds in our everyday lives. The next time you’re out and about, consider how a tiny hole in your eye, your pupil, is converting white light into colors and shapes. It’s amazing, isn’t it?

How UV Light Affects your Vision

UV rays aren’t visible to the eye, so you don’t know when you’re being exposed. Suffice it to say that if you’re outdoors, you’re being exposed to some degree of UV light, even during the winter. UV light is more intense at higher altitudes and during the middle of the day, from around 10:00 a.m. to 2:00 p.m. Some medications, including diuretics, tetracycline and sulfa drugs, can increase your sensitivity to UV rays.

Protect your peepers even on cloudy, cold days.

UV light can be divided into three parts:

• UV-C Rays — These, the highest-energy UV rays, are mostly filtered out by the earth’s ozone layer before they reach the earth’s surface.
• UV-B Rays — These rays have a longer wave length than UV-A rays and are responsible for sun tans (and sun burns.) UV-B rays are also linked to skin cancer, wrinkles and premature aging.
• UV-A Rays — Though they have lower energy than UV-C and UV-B rays, UV-A rays can pass through the cornea of the eye and reach the retina and lens, where they can do damage. Overexposure to UV-A rays has been linked to some forms of cataracts.

Long-term exposure to UV rays can lead not only to cataracts, but macular degeneration, skin cancer around the eyes and other eye disorders, so it’s important to protect your eyes each and every time you spend time outdoors.

Protecting your Eyes from the Sun

The EPA recommends protecting your eyes from UV rays by using a combination of a wide-brimmed hat and sunglasses that block between 99 and 100 percent of UV-A and UV-B rays. Those who wear contacts should wear UV-blocking contact lenses. For extra protection, choose wrap-around glasses that also offer peripheral coverage.

Not all sunglasses are created equally. Many are simply stylish, but don’t offer UV protection. That’s why it’s important to read the labels carefully or consult your optometrist about which sunglasses to wear. Protective sunglasses don’t have to be expensive. They just need to be designed to filter UV rays.

Don’t leave your eyes unprotected from the sun this winter. Ask your OKC optometrist to fit you for sunglasses that keep the sun’s damaging rays from reaching your eyes.

There are many external and internal factors that can impact your eyes. Temperature and weather, in particular, can play a tremendous role in your vision. For that reason, the harsh winter weather so common in Oklahoma can often be partially or entirely responsible for the condition known as dry eyes or dry eye syndrome.

What is Dry Eye Syndrome?

Some five million people age 50 and above suffer from dry eye syndrome, with millions more individuals of other ages suffering as well. Women are more susceptible to having dry eyes, but men can suffer from the condition too. When climate and temperature changes occur, the number of sufferers can spike dramatically.

Eyes need moisture in order to function properly. The eyes receive moisture in two ways: through the tear ducts and through humidity in the air. Tear ducts generally produce enough moisture to maintain the amount of fluid necessary to clean and lubricate the eye. When the amount of tears being produced diminishes, the eyes soon become dry.

What Causes Dry Eye Syndrome?

Humidity simply refers to the amount of moisture in the air. It is affected by such factors as climate and weather. Humidity levels tend to drop in the winter, making it more difficult for the eyes to stay properly moisturized. Because of this, many people who do not normally have any such eye problems will find that in the winter months they are suddenly faced with difficulty seeing or focusing.

Oklahoma’s winters play a large role in seasonal dry eye syndrome in this area, especially during the months of December, January and February when the lows can get down to the mid-20’s or below and the days are often hard-pressed to find their way out of the 30’s. As a result, we see plenty of patients who are suffering from a sudden loss of clear vision or persistent irritation of their eyes. When this occurs, we look at several factors to determine whether or not what they may be experiencing is, in fact, dry eye syndrome.

What are the Characteristics of Dry Eye Syndrome?

The most common symptoms indicating the presence of this syndrome can include:

• Inflammation and redness of the eyes
• A burning sensation in the eyes
• Itchiness in the eyes
• A sensation of having a foreign object in one or both eyes, but nothing is visible upon examination
• Blurriness and difficulty focusing

How to Treat Dry Eye Syndrome

The good news is that dry eyes can be easily treated in several different ways. One would be to use some type of prescription or over-the-counter lubricating eye drop. These medications can be administered directly to the eyes to relieve irritation and discomfort and provide needed moisture.

Taking certain natural supplements can also help your eyes stay hydrated, especially in a dry climate. Flax seed oil or fish oil supplements can be beneficial, as can drinking plenty of water.

Finally, if you tend to struggle with dry eyes regularly, you should consider running a humidifier in your home or office. This can help add moisture to the air around you, relieving the strain on your eyes.

Even if you believe your condition to be a simple case of dry eyes from winter weather, it is important that you contact us for a proper diagnosis and advice on the right form of treatment for you, just in case there is actually something more serious going on. As your local OKC optometrist, we can provide you with the best care possible to help you find the right solution for restored vision and comfort.

Of course, contact lenses have their own unique disadvantages. Like a pair of glasses, your contacts can accumulate dust and dirt, and even bacteria. Contacts can also cause some serious dry eye symptoms.

Recent technological innovations are making contacts more clean, comfortable, and long-lasting, though. At Dr. Guthrie’s office, we are now offering AIR OPTIX Aqua contact lenses. They’re the latest in silicone hydrogel (SiHy) lenses, and they can make your life a lot easier.

Because of their unique composition, SiHy lenses allow more oxygen to pass through the lenses to your eyes. That means your eyes will be whiter and healthier-looking, and that there’s less potential for bacterial binding to the corneal epithelial cells. It also means you won’t be able to “feel” the lenses as much. Some SiHy contacts even incorporate internal wetting agents to improve dry eye symptoms.

If you’re not always regular with taking out your contacts every night, the increased breathability of AIR OPTIX Aqua lenses is a big plus. (College students and night owls, we’re talking to you!) Some brands of SiHy lenses can be worn 24 hours a day for up to 30 days and nights, and there are plenty of options in between. Of course, contact lenses should be cleaned regularly – that hasn’t changed!

If you have astigmatism, ask Dr. Guthrie or our staff what SiHy options are available for you.

Although SiHy lenses are not necessarily as cheap as one pair of glasses (which, again, are prone to falling off of your face or getting stepped on), they’re definitely more affordable than replacing your HEMA contacts every week.

Plus, there are usually rebates available to make SiHy lenses more affordable: right now, you can buy an annual supply of AIR OPTIX Aqua lenses for less than the cost of an annual supply of Acuvue 2, the leading HEMA lenses. And most contact lenses are eligible for flexible spending account disbursements. It’s true that you get what you pay for – but with the Aqua lenses, you get a whole lot more.

Call us today at (405) 595-0423 or use our contact form to ask about switching over to SiHy lenses – your eyes will thank you! You can try them on at your appointment and even take home a trial pair the same day.

Interesting to discover that 87% of contact lens wearers are women!  And most are worn by the under 40s.  Contacts have become so comfortable now that this surprises me.  They’re not just for looks, many people find them more comfortable and convenient.

Here’s to hoping that more men and more of the over 40s get turned on to contract lenses.

History of the Contact Lens Optometry Infographic

We’re also planning to make blogging a regular part of what we do.  So stay tuned for more from our office.