Human Eye Movements for Vision Are Remarkably Adaptable

Posted on November 16, 2013 by Dawn Kaplan

Our eyes are constantly on the move, darting this way and that four to five times per second. Our eyes have the ability to change direction and focus at an incredible speed.

A new study published in the Cell Press journal Current Biology on August 15, states that researchers have found that the precise manner of those eye movements can change within a matter of hours. This discovery might lead to a way to help those with macular degeneration better cope with vision loss.

“The system that controls how the eyes move is far more malleable than the literature has suggested,” says Bosco Tjan of the University of Southern California. “We showed that people with normal vision can quickly adjust to a temporary occlusion of their foveal vision by adapting a consistent point in their peripheral vision as their new point of gaze.”

The fovea is the small, center-most portion of the retina, which is responsible for our Eye Chart high-resolution vision. In other words, it is the “pointer” we use to direct our eyes to different parts of a scene, building an image of our world. For those with age-related macular degeneration, increasing loss of foveal vision leads to visual impairment and blindness.

The researchers simulated a loss of foveal vision in six normally sighted young adults by blocking part of a visual scene with a gray disc that followed the individuals’ eye gaze. Once the disc was in place, the individuals were asked to complete demanding object-following and visual-search tasks. The researchers found that within three hours of working on those tasks, all six participants showed a remarkably fast and spontaneous adjustment of eye movements. Once the visual adjustment had been made by the participants, the change in their “point of gaze” was retained for a period of weeks and was reengaged whenever their foveal vision was blocked.

Tjan and the other two researchers stated they were surprised by the rate of this adjustment. They note that patients with macular degeneration frequently do adapt their point of gaze, but in a process that takes months, not days or hours. They suggest that practice with a visible gray disc like the one used in the study might help speed that process of visual rehabilitation along. The discovery also reveals that the oculomotor (eye movement) system prefers control simplicity over optimality. Tjan states “Gaze control by the oculomotor system, although highly automatic, is malleable in the same sense that motor control of the limbs is malleable.”

The result of this study is potentially very good news for people who experience loss of their foveal vision due to macular diseases. This study shows that it may be possible to create the right conditions for the oculomotor system to quickly adjust.

To read the original article, visit: https://www.sciencedaily.com/releases/2013/08/130815133447.htm

A Spoonful of Vegetable Oil Helps You See Better Longer?

Posted on November 9, 2013 by Dawn Kaplan

Can vegetable oil help combat blindness? Turns out it can!

The Research Center on Aging at the Health and Social Services Centre — University Institute of Geriatrics of Sherbrooke (CSSS-IUGS), England is the home of scientists who have been studying strategies for protecting retinal pigment epithelium (RPE) cells. There is a dysfunction of the RPE cells that is found in retinopathy and age-related macular degeneration, both of which are the leading causes of blindness in elderly people in developed countries.

Findings published in the Canadian Journal of Physiology and Pharmacology suggest that incubating retinal cells with vegetable oils induces biochemical and biophysical changes in the cell membrane, which may have a beneficial effect in preventing or slowing the development of retinopathy.

The research was centered around the fluidity of the membrane in the eye. The better the fluid in and around the membrane the smoother the eye operates. When there is not enough membrane fluidity the rotation and diffusion of proteins are affected. However, an increase in the membrane fluidity enables the membrane to be more flexible and eases the transmission of light through the eye.

The researchers discovered that the fatty acids present in vegetable oil integrate in retina cells and increase the plasma membrane fluidity.

So what does all this mean? The researchers concluded that a diet low in trans-unsaturated fats and rich in omega-3 fatty acids and olive oil may reduce the risk of retinopathy. Additionally, the research suggests that replacing the neutral oil found in eye drops with oil that possesses valuable biological properties for the eye could also contribute to the prevention of retina diseases.

This adds to the already established research that what you eat has a direct impact on your health and wellness.

To read the original article, visit: https://www.sciencedaily.com/releases/2013/08/130815113644.htm

Can Your Eyes Be a Window to Your Stroke Risk?

Posted on October 18, 2013 by Dawn Kaplan

Your eyes may be a window to your soul, but could they also be a window to your stroke risk?

In a recent study detailed in the American Heart Association journal Hypertension, researchers state that retinal imaging may someday help assess if a person is more likely to develop a stroke. This could be an invaluable diagnostic discovery – strokes Eyes and Strokes are the nation’s No. 4 killer and a leading cause of disability.

“The retina provides information on the status of blood vessels in the brain,” said Mohammad Kamran Ikram, M.D., Ph.D., lead author of the study and assistant professor in the Singapore Eye Research Institute, the Department of Ophthalmology and Memory Aging & Cognition Centre, at the National University of Singapore. “Retinal imaging is a non-invasive and cheap way of examining the blood vessels of the retina.”

Globally, high blood pressure is the single most important risk factor for stroke. However, until now there has not been a reliable way to predict which high blood pressure patients are more likely to develop a stroke.

THE STUDY:

Researchers tracked stroke occurrence for an average 13 years in 2,907 patients with high blood pressure who had not previously experienced a stroke. At the baseline, each patient had photographs taken of the retina, the light-sensitive layer of cells at the back of the eyeball. Damage to the retinal blood vessels attributed to hypertension — called hypertensive retinopathy — evident on the patient photographs was scored as one of four ways: none, mild, moderate, or severe.

THE FINDINGS:

During the follow-up, 161 participants experienced a stroke: 146 caused by a blood clot and 15 by bleeding in the brain.

After adjusting for several stroke risk factors such as age, sex, race, cholesterol levels, blood sugar, body mass index, smoking and blood pressure readings, researchers found the risk of stroke was 35 percent higher in those with mild hypertensive retinopathy and 137 percent higher in those with moderate or severe hypertensive retinopathy. The researchers determined that even in patients whose blood pressure was successfully controlled by medication, the risk of a blood clot was 96 percent higher in those with mild hypertensive retinopathy and 198 percent higher in those with moderate or severe hypertensive retinopathy.

While this research opens the door for early risk detection in patients with hypertension, Ikram states “It is too early to recommend changes in clinical practice, other studies need to confirm our findings and examine whether retinal imaging can be useful in providing additional information about stroke risk in people with high blood pressure.”

More research is being done on the benefits of retinal imaging. But one thing is for sure: retinal imaging would be an inexpensive and non-invasive way to assess risk.

To read the original article, visit: https://www.sciencedaily.com/releases/2013/08/130812170207.htm

Eyeball licking can be dangerous…you’re kidding!

Posted on July 11, 2013 by Dawn Kaplan

Eyeball-licking fetishism, also known as “oculolinctus” or “worming”, is gaining popularity as a way of expressing affection or inciting sexual arousal in Japan. With the increase of this activity, doctors are warning that there is a linkage to serious risk of virus conjunctivitis, other eye infections, and even blindness.

The oculolinctus craze in the country among young lovers has resulted in a significant increase in eye-infection cases. When the tongue makes contact with the eye, the eye is exposed to all kinds of infections and eye damage.

The trend of eyeball-licking was first documented when a Japanese school noticed that children were coming into class wearing eye patches. Apparently, one third of all the twelve-year-old children at the school had engaged in oculolinctus. This questionable trend was inspired by a Japanese emo band called “Born” in one of their music videos.

When interviewed by the Huffington Post on this phenomenon, ophthalmologist David Granet said “Nothing good can come of this. There are ridges on the tongue that can cause a corneal abrasion. And if a person hasn’t washed out their mouth, they might put acid from citrus products or spices into the eye.”

There is a very real risk of transmitting viruses. If the one who does the licking has herpes and/or a cold sore, there is a risk of human transmission via oculolinctus. If the licker suffers from halitosis (bad breath), they are more likely to have massive amounts of harmful bacteria in their mouth and on their tongue. Allowing such an individual to lick your eyeball (which has an absorbing membrane) puts you at risk of developing an infection.

Dr. Phillip Rizzuto, a spokesman for the American Academy of Ophthalmology said there is even a risk of eventual blindness. “The bacteria in the mouth are nothing like the bacteria in the eyeball, which is why we no longer recommend people lick contact lenses to moisten them.”

Animals use their tongues for personal hygiene (watch any pet cleaning itself). And in some cases, humans do the same (licking your thumb to remove a spot from your body). However, the tongue and mouth are designed to deal with a wide variety of pathogens that our eyeballs are not designed to deal with. There are many practices in the animal world that do not translate well to the human world. I think I can safely say that we all prefer our traditional handshake to the traditional method of introduction in the dog world.

If you want to show someone affection, hold their hand, give them a kiss or a hug. But PLEASE don’t lick their eyeball!

To read the original article click here: https://www.medicalnewstoday.com/articles/262012.php

This Just In

Posted on June 27, 2013 by Dawn Kaplan

New Layer In Human Eye Discovered

I just read an article dated June 16, 2013 about a new layer of the Human eye being discovered. This is great news for those people who need to have corneal graft or transplant.

The new layer, located in the front layer of the eye, is being called the “Dua Layer”, so named after the researcher (Professor Harminder Dua) who led the study in which the discovery was made. Dua explained the significance of the discovery in this way:

“Having identified this new and distinct layer deep in the tissue of the cornea, we can now exploit its presence to make operations much safer and simpler for patients.”

He went on to add:

“From a clinical perspective, there are many diseases that affect the back of the cornea, which clinicians across the world are already beginning to relate to the presence, absence, or tear in this layer.”

With over 65,000 penetrating corneal graft procedures being carried out worldwide each year, surgeons will benefit considerably by understanding more about the new Dua’s layer, which will improve outcomes for patients undergoing corneal grafts and transplants.

This discovery will alter the way these surgeries are preformed and therefore chances of tearing during surgery will be significantly reduced.

On a side note, this discovery means that ophthalmology and anatomy textbooks will literally have to be re-written. Not a bad price to pay for the advancements this discovery will yield.

Click here to read the original article: New Layer in the Human Eye Discovered