by COVD Director Mary Beck, OD, FCOVD

Not all vision screenings are created equal!

Many people are familiar with the “eye chart test” used in typical vision screenings and the score it gives–the phrase “20/20” is usually thought to mean the same thing as “perfect vision.” However, most vision screenings provided at school or at the pediatrician only check for “distance visual acuity” (the ability to tell apart letters from far away), and are unable to test functional vision. This can miss over half of the visual problems that can hold kids back in the classroom, sports, and life!



Did you know that 25% of children in the U.S. have a vision problem significant enough to affect their performance in school? In learning disabled populations, it can impact as many as 3 out of 4 individuals! But because of the limits of the eye chart, most of these children can still pass a traditional vision screening and even score 20/20 or better, and because they don’t know the aren’t seeing the world like everyone else is, they don’t know to ask for help.

Vision problems are not outgrown and continue to impact performance into adulthood, and concussions or other brain injuries can also significantly impact your ability to see clearly. Many of these problems can cause significant, lasting difficulty in school and work, but are missed entirely by an “eye chart test.”

So, what’s the alternative to the eye chart?

A comprehensive vision exam!

In addition to testing for eye health and acuity, comprehensive vision exams also test your eyes’ abilities to function together as a team with particular skills. While acuity is based on eye shape (that’s why you need glasses to fix it,)  visual skills are not present when we’re born and we have to learn them as we develop. Here are some functional skills that a comprehensive vision exam checks:

Distance Visual Acuity

Even though a distance visual acuity test (the eye chart) only tests eye sight, or clarity, it is still an important test!  It checks for myopia (nearsightedness), astigmatism, and amblyopia (lazy eye). Amblyopia is the most common cause of vision loss in children and not many people know that it can be prevented or reversed!
Symptoms of a possible problem with this skill: Blurry vision, headaches, squinting, rubbing eyes.

Near Visual Acuity

Individuals who have hyperopia (farsighted) have more trouble seeing up close than far away and use their focusing system harder to zoom in and make and keep objects clear. Most will pass a traditional visual acuity screening test, since they often see great far away and can focus harder for short period of time up close to pass a near test. Even if blur is not reported, hyperopes have to work harder to sustain their visual focus up close. 23% of all school age children are moderately to severely farsighted, but this more than doubles to 54% in children with reading disabilities!
Symptoms of a possible problem with this skill: Intermittent or constant blurry vision, difficulty with attention on task, fatigue, daydreaming, transposing words, re-reading, headaches.

Oculomotor – Eye Movement Control (Tracking)

Often referred to as tracking, this is the ability to hold visual attention, move our eyes across a line of text, maintain eye contact, track a moving target and rapidly shift eyes from target to target. Poor eye movement control often impacts reading.
Symptoms of a possible problem with this skill: Loss of place, difficulty copying from board, re-reading, skipping small words, difficulty hitting/catching a ball.

Accommodation – Eye Focusing

This is the ability to change focus between near and far distances and sustain target clarity at all distances. A focusing problem can occur even without being nearsighted or farsighted, so you can struggle with one but still have 20/20 eyesight!
Symptoms of a possible problem with this skill: Short attention span, reduced reading comprehension, task avoidance, excessive time completing assignments, daydreaming, fatigue, headaches, blurred print.

Vergence/Binocularity – Eye Posture & Teaming

The motor ability to align eyes accurately on a target and help to combine (fuse) images from both eyes into one image to help us to localize where the target is and achieve depth perception.
Symptoms of a possible problem with this skill: Words moving on the page, transposing words, headaches, fatigue, poor handwriting, motion sickness, closing or covering an eye, inattention, clumsiness, difficulty with ball sports and eye-hand coordination.

COVD Quality of Life Visual Symptom Checklist (QOL)

COVD has developed standardized visual symptom checklist used in several studies that assesses signs and symptoms related to visual inefficiencies. If you or your child scores higher than 25, there is a much greater risk for having functional visual difficulties. Click below to use the online QOL!

Health matters, but that’s not all

Possibly the most important part of a comprehensive vision exam that an eye chart can’t replace is the testing of your eye and visual pathway health. Illnesses or problems in these areas which do not impact sight are often symptom-free, but can be a sign of serious health concerns or even lead to vision loss. Annual vision exams are an important part of monitoring your health and essential in detecting problems before it is too late.

Did you know that, as an important part of prevention and wellness, the American Optometric Association recommends an eye health exam at 6 months, 3 years, 5 years of age, and annually thereafter? However, even these types of exams typically do not test for visual function in all the way expressed above. Just as most individuals that have vision-related learning difficulties can still score 20/20, they can also be declared to have healthy eyes.

See the whole picture

Good vision is measured by much more than the 20/20 of an eye chart, and takes more than a clean bill of health to know you’re seeing at your best. To ensure that you are including function in your pursuit of perfect vision, Locate a Doctor in your area who specializes in comprehensive vision exams!