Alamo Optometry Blog

September 1, 2008

Vision Screenings vs. Vision Examinations…What is the Difference?

Filed under: Educational — Tags: — admin @ 11:14 pm

(As appeared in Alamo Today Sept 2008 edition, pg.27)

This question comes up often in practice as parents are questioning whether or not a screening at school or their child’s pediatrician is sufficient to ensure good vision and eye health. Obviously, each parent must make their own decision; however, here are some of the glaring differences between a screening and a comprehensive examination.

Vision screenings conducted at school or in a doctor’s office test for distance vision only. Since distance vision is defined at 20 feet, a child might pass this without any difficulty, but gives no information whether a child can read a book and use the eyes well as a team up close. If the screening is done at school, a rough determination of prescription and eye alignment is attempted without the use of any machines. This information is then used to either pass or fail the child. However, the standards for pass/fail are arbitrary and can differ from clinic to clinic and child to child. The last thing to consider about a screening is who is conducting the test. Most of the time it is a doctor’s assistant or nurse at the pediatrician’s office, and at schools, an optometrist or school nurse conducts the screening. However, in both circumstances, the ability for the child to focus on the tasks at hand and for the tester to get accurate results are often compromised due to the noise and distractions of other children and students waiting to be tested.

Comprehensive eye examinations should be conducted by an eye care professional. Optometrists have the necessary training and experience to make a diagnosis of vision, binocular vision, and health status and to recommend treatment if needed. Often, the necessary equipment and tests to fully evaluate the status of the eyes are not available at a vision screening. Here are just some of the highlights of a pediatric exam at our office.

Visual acuity at distance and near is determined. Since a child needs to be able to see and function at many distances, simply testing distance only is not sufficient. In addition, the focusing ability is also assessed. Your child needs to focus on the board or overhead and then to their notes or book and back all day long. The ability for sustained focusing also allows your child to attend to reading and writing for a period of time.

The exact prescription for good comfortable vision is determined. Amblyopia, or “lazy eye”, occurs in about 8% of the pediatric population, and is when one or both eyes cannot be corrected to 20/20 vision. The need to correct this is important early in life to help both eyes develop and see well. Sometimes glasses or contact lenses are needed and sometimes they are not; however, knowing the exact status of the eyes is paramount.

Binocular vision, color vision, eye movements, and depth perception are all tested. If your child cannot move his/her eyes well to track objects, or to differentiate colors well, activities such as reading, sports, and copying information from the white board will be affected. Good eye alignment allows the muscles in the eye to converge (come together) and diverge (move apart) depending on the task. This allows for good depth perception and a precise eye alignment so the brain can fuse what it sees from each eye into a single, clear image.

Finally, the health of both the front and back (retina) part of the eyes is determined by examining all structures through the use of a microscope and lenses. We will also measure of the pressure in the eyes, and use drops if needed to make the health assessment process easier.
Even though most screenings figure out which children need to be evaluated further, it is based on decreased distance visual acuity alone. As stated above, many things aid or are a detriment to good and comfortable vision, and are usually not evaluated at a screening. My recommendation is to have your child’s eyes examination early (preschool age or by kindergarten), and if a recommendation for a vision evaluation is given, we would be more than happy to examine your child and give you an honest recommendation based on the findings of the exam.

Dr. K. at Alamo Optometry is your hometown eye doctor for outstanding service, vision care, and designer eyewear. He can be reached at 925-820-6622 or visit his office at 3201 Danville Blvd., Suite 165 in Alamo.

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