Tag: Visual Acuity

20/20 Vision

Karen Griffith

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.

Good Vision and Learning

Karen Griffith

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.

 

[heading centered=”yes” margin_bottom=”no”]What is Good Vision?[/heading]

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.