Binocular Vision

23
Aug

What does a Baby See?

An infant’s vision improves significantly during his first 6 months. Basic visual function develops rapidly during the first year.

Newborns focus on objects that are 8-10 inches away and will wince and blink in response to bright light, but only for a brief amount of time. At birth approximate visual acuity is 20/800. Infants will stare intently at high contrast images such as the edges of faces. Newborn eyes may cross or wander for the first 4 months.
By two to three months, babies have an approximate visual acuity of 20/400. At this age, they will track movement as well as smile at objects that are about a foot away. Reaching for objects around 3 months is expected.
At 6 months the vision has improved to at least 20/100. A 6 month old infant will open his mouth to a spoon and will recognize his own face in the mirror. Both eyes should focus equally. Depth perception is developing.
A twelve month old child will have visual acuities of 20/60 and can judge distances fairly well, throw things with precision and pick up small objects with the fingers and thumb.

A comprehensive visual assessment between 9-12 months is recommended, earlier if the infant is at risk for eye or vision disorders. Early intervention is critical to successful vision and treatment.

Acuity Testing Infants

Preferential Looking Test

1
Sep

Vision Screening Vs. Vision Exam

The department of motor vehicles, the school nurse and the pediatrician use vision screening to identify vision problems. Screening usually involves standing a given distance from a lettered chart, covering one eye and reading down the chart to the smallest letter possible.

SNELLEN

A vision screening is intended to help identify children with eye or vision problems that threaten sight or impair their ability to develop and learn normally. However, vision screenings are a limited process and cannot be used to diagnose an eye or vision problem, but rather to indicate a potential need for further evaluation.

Screenings are typically designed to detect problems with distance vision, and that is important for children socially and physically, but myopia represents the least risk for reading and learning. A myopic child is more likely to notice that the board is blurry and move to the front of the classroom. Hyperopia on the other hand, makes it more difficult to see things close up and astigmatism effects vision at all distances. Children with uncorrected hyperopia and astigmatism will have more difficulty reading and writing and may not even be aware that the difficulty is due to his or her vision. These are the children that may complain of headaches, avoid reading and school related tasks.
A vision screening test identifies some vision problems, but can miss disorders that have a profound effect on a child’s ability to succeed in school.

During a comprehensive eye examination an optometrist can identify, diagnose and prescribe treatment.

23
Aug

Back to School – Vision Problems Could Equal Behavioral Issues

This article was recently released by the California Optometric Association.
The back-to-school season is the time to make sure your child is fully prepared and ready to take on the challenges of school. Perhaps the most overlooked, yet immensely important part of that preparation is the all-important vision examination. There is a very strong relationship between vision and learning, as well as vision and behavior in the classroom.

Back to school Children who do not have the necessary visual-motor and visual-perceptual skills to compete in the class room with their classmates, may act out, be easily distracted or not be able to pay enough attention to perform to their potential. A 15 year long study at the San Bernardino Juvenile Hall revealed that a much higher percentage of juvenile delinquents have vision problems than in the average population. According to the study by optometrists Stan Kaseno and Kristy Remick, poor visual skills can contribute to poor self-esteem, which can lead to poor attitudes and behavior in school. After a program that addressed the inmates problems, including vision and victim’s awareness classes, the repeat offender rate decreased from 90% to 15%.

All students should have their vision and visual skills checked yearly by an optometrist before going back to school to make sure they have the learning readiness skills that are so important to academic and athletic performance.

Here are some signs to look out for that could indicate that your child has a possible vision problem:

Behavioral Signs:

  • Poor attention in the classroom
  • Not performing to potential
  • Doesn’t like, or refuses to do homework
  • Doesn’t like sports
  • Slow reader
  • Difficulty completing timed exams

Signs of Difficulty with Visually-Related Tasks:

  • Loses place frequently while reading
  • Headaches or eyestrain associated with reading or computer use
  • Words go in and out of focus
  • Words appear to “move” on the page
  • Double vision (constant or intermittent)
  • Having to re-read over and over for comprehension
  • Difficulty recalling what was read
  • Poor handwriting

If your child has any of the above problems, and is not performing to his or her potential in school and sports, schedule an eye examination. It is important to detect and treat any underlying vision problems that may be interfering with school performance.

 

16
Sep

20/20 Vision

During an eye examination, I always use the eyechart to measure the distance vision, usually with the most current glasses or contact lenses. This gives me a place to begin and tells me what sort of vision a person has and a quantity to compare. snellen chart
The classic example of an eye chart is the Snellen eye chart, developed by Dutch eye doctor Hermann Snellen in the 1860’s. There are many variations of the Snellen eye chart, but in general it has 11 rows of capital letters. The top row contains one letter (usually an E). the other rows contain letters that are progressively smaller.

In the United States, the standard placement of the eye chart is on a wall that’s 20 feet away from your eyes. Since most of our exam rooms are shorter than 20 feet we use mirrors to simulated the 20 foot distance. 20/20 vision is considered “normal vision”, meaning you can read at 20 feet a letter that most human beings should be able to read at 20 feet.

In the US a person is considered “legally blind” if his best-corrected visual acuity with glasses or contact lenses is 20/200 or worse. To get a driver’s license in California a person must have at least 20/40 best corrected acuity.

An eye chart is a measure of visual acuity only. It is an aid to prescribing glasses and contact lenses. But eye charts don’t measure peripheral vision, depth perception, or color perception. They also don’t determine the ocular health.

The visual acuity measurements done with the Snellen eyechart are simply a starting place for any eye examination, a method to quantify it.

31
Aug

Good Vision and Learning

Vision is a dominant process in the growth, development and daily performance of children. Many children with undetected vision problems struggle in the classroom. Some symptoms of learning related vision problems are:

  • Trouble finishing written assignments
  • Losing ones place when reading
  • Having a short attention span when doing close work
  • Skipping words when reading
  • Making errors when copying from a classroom board
  • Having greater potential than grades may indicate (under-performing)

Vision problems can affect comprehension performance in reading and manifest as social, eye-hand coordination, discipline, or emotional problems. From there, such vision problems can impact the rest of your child’s life and ability to succeed.

 

What is Good Vision?

Back to school Visual Acuity: It’s important to realize that good vision is more than 20/20 eyesight, Invented in the 1860’s, the term 20/20 indicates if you can see letters 3/8″ high at 20 feet. This does not take into account the eyes’ ability to see books or view the computer screen.

Eye Health: Eye disease can impair vision or lead to vision loss if not diagnosed and treated.

Visual Integration: The ability to process and integrate visual information, which includes and coordinates input from our other senses and previous experiences so that we can understand what we see.

Eye Teaming: The ability of the eyes to work properly together.

Eye Focusing: The ability of the eyes to focus and shift focus to near and distant points easily and effortlessly.

Eye Motility or Tracking: The ability of the eyes to move together across a page of print, to directly view an object, to move from one viewing area to another, or follow a ball.

The good news if that with early diagnosis and appropriate, comprehensive intervention, the prognosis is good in a majority of cases. Schedule your child’s eye examination to make the most of the new school year.

20
Aug

Back to School with Technology

Today’s gadgets and devices are placing demands on young eyes. The benefits of technology have a downside, especially when it comes to the eyes. Stress on the accommodative system (focusing) causes eye fatigue.

This can cause headaches, blurred vision and other related chronic discomforts.
Nearly 1 in 4 children are on digital devices 3 or more hours per day.
School text books are rapidly moving to tablets
40% of young adults spend at least 9 hours per day on digital devices.

Computer lab

10 things you should know about digital eyestrain:

  • BLURRED VISION Think about how you look at your phone, then your computer screen, back to your phone then at the TV. Like any muscle that is holding in one position for a length of time it contracts and then has a hard time relaxing. Same goes for your eye muscles. You have been looking at near objects, the muscles have contracted, then you quickly look up and the muscles have locked up and can’t relax and your vision becomes blurred.
  • TIRED EYES. Any muscle that is fatigued is going to be sore and tired.
  • HEADACHES. When your eyes are tired you will get headaches. This type of headache tends to occur around the eyes.
  • BODY FATIGUE. At the end of the day patients are finding they are just too tired and need to close their eyes. When the eyes are closed there is nothing for them to foccus on and the muscles can relax.
  • DRY EYES. Your blink rate goes down when the eye is focusing. Every time you blink the eye needs to readjust and that is work for your eye so the blink rate drops when you focus at near work. It can drop to 10 times a minute for computer work and 4 to 6 times a minute when looking at a smart phone or tablet. Not blinking allows the eyes to dry.
  • LIGHT SENSITIVITY. Eye muscles are extremely tired when working all day. When light comes into your eye it constricts the pupil which is right next to the ciliary body. the muscles that focus the eye. So when light comes into the eye it is a similar feeling to focusing. It is similar to lifting weights all day then someone comes along and punches you in the arm. That muscle is sore and tender.
  • EYE RUBBING. What tired muscle doesn’t feel good when you rub it?
  • POOR NIGHT VISION. Our eyes do not know how to focus on light. If you are staring at a light in the distance you wouldn’t be able to tell how far away it really is.
  • REDUCED CONCENTRATION. Any time a muscle is over used, such as the eye focusing on light all day, it becomes more difficult for the eye muscles to continue to hold that position.
  • DOUBLE VISION. Diplopia or double vision is caused when the eyes do not work together. Staring at near objects such as a computer, phone or tablet require persistant converging and diverging all day. The muscles become so tired they lose the ability to hold a position and we see double.

It is difficult to avoid the use of computers and tablets, but you can take steps to reduce digital eyestrain. Wearing the correct prescription and taking advantage of blue light blocking coatings are 2 ways to make your eyes more comfortable. Make an appointment.

 

19
Nov

BOOK REVIEW: The Mind’s Eye

The author of The Mind’s Eye., Oliver Sacks, is a neurologist who has written books on the various senses, brain function and dysfunction and perception. He makes challenging, vague Vintage-Minds-Eye-2011-194x300topics more obtainable to the layperson.
The Mind’s Eye is about different visual perception related conditions ranging from agnosia (inability to recognize and name objects), stereopsis, and peripheral vision.
Of the seven different topics/chapters my favorites were “Stereo Sue” and “Persistence of Vision.” Susan Barry is a neuroscientist who had been cross-eyed since infancy. Susan had strabismic surgery as a child to straighten her eyes but lacked fusion, the 2 eyes didn’t work together.She grew up viewing a flat world until she finally met an optometrist who created a vision training program for her. Due to her motivation and interest in perception she succeeded in obtaining stereo vision. Her two-dimensional world became three-dimensional. She has written a book about her journey into three dimensions – Fixing My Gaze. If you are interested in stereopsis, have a strabismic child or lack depth perception yourself I strongly recommend her book.

“Persistence of Vision”  is a journal of Oliver Sacks’ own experience slowly losing vision  in one eye due to a tumor. He scolds himself for missing his annual eye exams which would have detected the tumor earlier. Losing his vision in one eye caused the loss of stereovision and peripheral vision. As a neurologist, Sacks analyzes not only the loss of peripheral vision but the loss of awareness in the visual field. He had to learn to deal with moving around without awareness of objects to his right, this resulted in a lot of bruises on the right side of his body.

In the first pages of the book, Sacks describes the human variation in visual imagery, peoples ability to visualize something without actually seeing it. At the end of the book he gives examples of individuals who have profound enhancement of the remaining senses when one is lost and other individuals who don’t gain sensitivity. The one consistent factor of the brain and human perception is that it isn’t consistent.

My one complaint of the book is the footnotes on nearly every page. By the end of the book I was annoyed to the point where I had to ignore the footnotes to finish reading the text.

19
Aug

Electronics and Kids Eyes

This is my last back-to-school  post for the year, but I feel  very strongly about providing children with good vision. A vision screening performed in the pediatrician’s hallway or the vision test done at school are no substitute for a comprehensive eye examination.

Eye chart - kids exams

My focus today is the use of technology: phones, games, computers and tablets. Summer vacation probably wasn’t much of a break from electronic devices for most children. The integration of technology into the classroom is more reason for children to have an eye examination.

  • Kids are digitally connected longer than parents think. According to a survey done by the American Optometric Association (AOA), 83%of children report using an electronic device more than 3 hours daily while only 40% of of parents think their kids exceed that mark; furthermore, 42% of kids report 5 hours of use or more.
  • All that time can cause eye problems. 80% of children report their eyes have burned, itched, felt tired or had blurry vision after using an electronic device.
  • Kids aren’t taking appropriate breaks. Students should follow the 20-20-20 rule. This simple rule advises that after 20 minutes of computer, tablet or other device work, the user take 20 seconds to look in the distance at least 20 feet away.
  • Most learning happens visually. An estimated 80% of all classroom learning happens through visual pathways – nearly all tasks a child performs depend on good vision.
  • Get children eye exams early. I recommend a child’s first eye exam happen at 6-12 months of age.

Get your kids off to a good start this school year. Schedule a back-to-school  eye examination.

5
Aug

Back-to School

Back to school

I know it’s tough to think about school starting in a few weeks. While you are scheduling immunizations, sports physicals and dental appointments, don’t forget the most important sense used in school – VISION.
Nearly 80% of learning is done through a child’s eyes. Reading, computer usage and whiteboard work are all visual tasks students perform everyday. A child’s eyes are always in use in the classroom. Therefore, when a child’s vision is not working properly learning and class participation will suffer.

Children with undetected vision problems are sometimes inaccurately diagnosed with attention deficit disorder (ADD) or attention deficit hyperactivity disorder (ADHD). When vision is difficult, it requires greater effort than normal causing the child to avoid close work.
Many children with undetected vision problems struggle in the classroom. Listed here are some of the behaviors associated with vision problems:

  • Trouble finishing written assignments
  • Losing his place when reading
  • A short attention span when doing close work
  • Skipping words when reading
  • Having greater potential than grades may indicate

Start the school year off right, schedule a comprehensive eye exam for your child.

22
May

Screen Time

Small Screen Digital devices are getting smaller and smaller. This is great for portability, but not so great for the eyes.
Smaller devices mean smaller screens and that means the print is pretty tiny. The tendency is to hold the device closer to try to see the smaller text, but this requires greater effort to focus and keep the eyes aligned.
Also, depending on the screen resolution, holding the screen closer to the eyes can cause pixilation of characters, which blurs the text and contributes to eyestrain.
To reduce the risk of eyestrain from smaller screens, adjust the print to a larger size, increase the brightness of the screen to match your surroundings and take frequent breaks when reading long passages of text.
For sustained reading, use a tablet or notebook device and hold it farther from your eyes for greater viewing comfort. Or better yet, go outside and take a walk.