New Vision of How We Explore Our World

Apr. 4, 2013 — Brain researchers at Barrow Neurological Institute have discovered that we explore the world with our eyes in a different way than previously thought. Their results advance our understanding of how healthy observers and neurological patients interact and glean critical information from the world around them.

The research team was led by Dr. Susana Martinez-Conde, Director of the Laboratory of Visual Neuroscience at Barrow, in collaboration with fellow Barrow Neurological Institute researchers Jorge Otero-Millan, Rachel Langston, and Dr. Stephen Macknik, Director of the Laboratory of Behavioral Neurophysiology. The study, titled "An oculomotor continuum from exploration to fixation," was published in the Proceedings of the National Academy of Sciences.

Previously, scientists thought that we sample visual information from the world in two main different modes: exploration and fixation. "We used to think that we make large eye movements to search for objects of interest, and then fix our gaze to see them with high detail," says Martinez-Conde. "But now we know that's not quite right."

The discovery shows that even during visual fixation, we are actually scanning visual details with small eye movements -- just like we explore visual scenes with big eye movements, but on a smaller scale. This means that exploration and fixation are two ends of the same continuum of oculomotor scanning.

Subjects viewed natural images while the team measured their eye movements with high-speed eye tracking. The images could range in size from the massive, presented on a room-sized video monitor in the Barrow Neurological Institute's Eller Telepresence Room, normally used for Barrow's surgeons to collaborate in brain surgeries with colleagues around the world, to images that are just half the width of your thumb nail.

In all cases, the researchers found that subjects' eyes scanned the scenes with the same general strategy, along a smooth continuum of dynamical changes. "There was no abrupt change in the characteristics of the eye movements, whether the visual scenes were huge or tiny, or even when the subjects were fixing their gaze. That means that the brain controls eye movements in the same way when we explore and when we fixate," said Dr. Martinez-Conde.

Scientists have studied how the brain controls eye movements for over 100 years, and the idea -- challenged here -- that fixation and exploration are fundamentally different behaviors has been central to the field. This new perspective will affect future research and bring focus to the study of neurological diseases that impact oculomotor behavior.

Valentine's Day Ficklets

Study Finds Children’s Headaches Rarely Indicate a Need for Eyeglasses

Often times, when a child has reoccurring headaches, we think it's associated with potential vision problems. A new study from November 2012, provided the first clear evidence that vision or eye problems are rarely the cause of reoccurring headaches in children even when the headaches start while doing school work or at school. 

At the 116th Annual Meeting of the American Academy of Ophthalmology, the "retrospective study, which was conducted at the ophthalmology clinic of Albany Medical Center in New York state, researchers reviewed the medical records of 158 children under age 18 who were seen at the clinic for frequent headaches from 2002-11. All of the children received complete eye exams by the clinic's ophthalmologists.

No significant correlation was found between their frequent headaches and a need for vision correction. The researchers reached this conclusion by comparing the results of the clinic's exams of the children with headaches to the records of their previous eye exams and other relevant medical care. Eye health and vision test results remained unchanged from earlier exams for 75 percent of the children. Also, children who already had eyeglasses were not found to need new prescriptions at the time they were seen at the clinic for headaches. Although about 14 percent of the children reported that their headaches occurred while doing visual tasks like homework, and about nine percent reported visual symptoms associated with their headaches, a need for vision correction did not appear to be the primary cause or a significant factor in any of these cases, according to the study."

Although the study finds that headaches is not a reliable indicator for vision issues, it's a good idea to have your child undergo annual eye exams.

To read the full article, click here.

Kids that Wear Glasses More Likely to Pass Classes

Did you know that kids that wear glasses are more likely to pass classes?  According to optometrist Bruce McNeel, in an effort to get parents to have their children's eyes tested, children's eye exams should be a standard back to school ritual.  Sight is involved in more than 80% of learning which equates to trouble if your child is one of the children having difficulty seeing.  Dr. McNeel furthers his efforts by teaching that children should have an eye exam by age three (unless issues are detected earlier).

Some warning signs that your child might be suffering from vision problems include the following:

Children could be suffering from myopia (short-sightedness) if they:
  • SIT closer than two metres away from the TV
  • Position themselves closer than 40 cm from a computer screen
  • HOLD reading materials very close to their face
  • SQUINT when trying to view distant objects and read a whiteboard

Signs eyes may be fatigued and strained:

  • RUBBING eyes

Children may have vision-related problems if they regularly:

  • SKIP lines when reading
  • LEAVE out or confuse small words when reading
  • TURN or tilt their head to use one eye only
  • ARE often clumsy
Click here to read the rest of the article.