My eye doctor prescribed spending time outside

We have all heard about how much time kids spend inside watching TV, studying, and playing video games. My seven-year-old son is addicted to rainbow looms, and could loom all day if I let him. New studies have indicated that the amount of time children spend outside may decrease the risk of developing myopia.

What is myopia?

Myopia, or nearsightedness, is a vision condition in which close objects are seen clearly but far objects appear blurred. Nearsightedness is a very common vision condition, affecting nearly 30 percent of the US population, and up to 90 percent of developed East and Southeast Asian countries such as Singapore, Taiwan, China, Japan and Korea. Myopia typically presents in school age children. Because the eye continues to grow as children grow, myopia may progress until approximately age 21.

Photo Courtesy of Shirley Binn

Photo Courtesy of Shirley Binn

Recent studies have indicated that more time spent on near work, less time spent outdoors, higher educational level and parental history of nearsightedness are risk factors for developing nearsightedness. Spending time outdoors plays a crucial role in myopia development and can slow its progression.

A recent study presented at the Association for Research in Vision and Ophthalmology (ARVO) 2014 Annual Meeting demonstrated the importance of time spent outdoors in order to control nearsightedness. The study evaluated visual acuity (vision) and axial length (length of the eye) of 6690 multiethnic children at 6 years of age. Axial length was significantly longer in children who spent less than one hour per day outdoors than in those who spent more than 2 hours outdoors.
Jan Roelof Polling, at the University of Applied Sciences Utrecht, lead investigator of the study recommended “Children with an increased risk of near-sightedness, such as those from a near-sighted family, should be prompted to spend at least 15 hours a week outside and should avoid spending long hours doing near work, even when they are very young.”

Photo Courtesy of RavEytan

Photo Courtesy of RavEytan

How does spending time outdoors help with myopia progression?

The protective effect of being outdoors is not well understood. Researchers suspect that bright outdoor light helps children’s developing eyes maintain the correct distance between the lens and the retina, keeping vision in focus. The intensity and / or specific spectral distribution of outdoor lighting may be beneficial. Indoor lighting that is dim does not provide the same kind of feedback. Therefore, when children spend too many hours inside, their eyes fail to grow correctly and the distance between the lens and retina becomes too long, causing far-away objects to look blurry. Hormonal changes associated with outdoor activities may also be beneficial.

Encouraging children to spend more time outdoors can be a simple and cost-effective way to improve their vision and general health. Head outside and enjoy the summer! Just remember to keep spending time outside when school resumes.

Melissa Barnett, OD, FAAO

California Optometric Association

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Why 20/20 isn’t perfect-What is visual acuity?

Courtesy of riekhavoc (caughtup?) on Flickr

Courtesy of riekhavoc (caughtup?) on Flickr

Measuring normal vision

When patients come to see me, I need to have a way to compare how they see in relation to someone with normal vision.  So, like most eye doctors, I use a number system called Snellen visual acuity.  This measure of the clarity of vision uses black letters on a white background.  If you have ever had an eye examination, it is when the doctor asks you to read the letters on the chart that starts with a big “E”.  The letters are called optotypes and they have a very specific design that takes into account the size of the lines and the space between them.  While there are other types of visual acuity measurements, this is the most common.

20/20 isn’t perfect

The measure most people want to achieve with Snellen visual acuity is 20/20 vision.  While 20/20 is pretty darn good vision, in reality, 20/20 is not exceptional vision so much as it is more like the lowest possible visual acuity a person can have and be considered normal.  In fact, many people have the potential to see somewhere between 20/16 and 20/12 which means that they see even better than 20/20!

Paul B. (Halifax)

Paul B. (Halifax)

What do the numbers mean?

People also ask me to explain what the numbers mean.  As an example, take a person with 20/40 vision.  A person with 20/40 is at a disadvantage compared to a person with normal, 20/20 vision.  In fact, a person with 20/40 vision would have to stand 20 feet away from something that a person with normal vision can stand 40 feet away from and still see.

A number of factors like eye disease, the eye’s length and curvature, and the quality of connection between the eye and the processing centers in the brain come together to determine visual acuity.  Some factors, like nearsightedness, come with easy solutions like glasses.  Others, like macular degeneration, are much more complex and simple solutions like glasses only offer minimal improvement.  If a patient has very poor visual acuity, they may need magnifiers and telescopic lenses to help.

So,  the next time you go to the optometrist, give the 20/15 line a shot.  Good luck!

~David Ardaya, OD
California Optometric Association
http://eyehelp.org
http://www.coavision.org

What did my doctor just say? Common terms your eye doctor will use and what they mean

Courtesy of riekhavoc (caughtup?) on Flickr

Courtesy of riekhavoc (caughtup?) on Flickr

Have you ever felt like you were not quite sure what just happened at your optometrist’s office? It is difficult enough to answer the “which is better, one or two?” questions and then at the end of the exam to try and understand the doctor’s explanations with difficult optometry terms without secretly worrying that you might have said something wrong!

Hopefully this blog will help you better understand some of the more common terms we use in our examinations.

1) First of all, most comprehensive exams will include a detailed case history. The doctor will want to know your family medical and ocular (eye) history. Some terms you may hear include the most common eye diseases – cataracts, glaucoma and macular degeneration.

  • Cataract is the term used when the natural lens of your eye becomes cloudy, causing blurred and distorted vision.
  • Glaucoma is the eye disease that causes your eye to have excessively high pressure, which can lead to long-term damage of the nerve in the eye.
  • Macular degeneration is a disease that affects your central or straight ahead vision.

Not only will the optometrist ask you about a family history of any of these conditions, they will also assess your eye health and your possible risk for developing any of them.

2) Next, the optometrist will perform a refraction to get you the best possible glasses or contacts that will correct your vision.

  • A refraction is just the process of determining for each individual what are the best lenses to give you maximum visual clarity and comfort at both distance and near.
  • Myopia – nearsightedness or the ability to see better at near than at far.
  • Hyperopia or farsightedness, really means that it is more difficult to focus at near and at far distances.
  • Astigmatism: this refers to the shape of the front surface of the eye being more football shaped rather than basketball shaped.

3) There are a few terms you might hear specifically in an child’s exam.

  • Pursuits: slow, smooth eye tracking.
  • Saccades: fast reading eye tracking.
  • Accommodation: focusing.
  • Binocularity: the ability of the eyes to work together as a team.

4) Finally, there are some terms regarding glasses that it might help to define.

  • Progressive lenses are the kind of “no line bifocal” that you might hear about on TV. But, unlike a bifocal, where there are two areas of vision, near and far, progressives have an unlimited amount of areas as you look from distance to near in the lens.
  • Transition lenses are the kind that change to dark outside. They undergo an anti-reflective treatment, which eliminates all glare and allows for crisper vision, especially at night.

Hopefully, this quick explanation helps with some of the confusing terms in an eye exam. As for any others, always ask your optometrist to explain something that does not make sense.

~Lisa Weiss, OD, MEd, FCOVD
California Optometric Association
http://www.coavision.org