The important back to school vision test

It is estimated 80-percent of learning for a child is done through their eyes. So if something is wrong with their vision, they will likely have trouble in school.

A routine vision test is good, but it's not enough to catch all problems early when they can be treated quickly.

Laptops, tablets, smartphones and yes, even books. Children are using their eyes now more than ever.

And optometrist Dr. Robin Sapossnek says screenings in school can miss vision problems, so a full exam is a must.

"You can have 20/20 eyesight and still have focusing and aiming problems," Dr. Sapossnek explains.

Not being able to easily follow objects is a sign of those problems.

Last year, Sam Hopkins needed therapy when a concussion left her with eyes that didn't work together. She also had severe light sensitivity.

Chronic redness, tearing, headaches or rubbing the eyes are other signs of trouble. Parents should look for those, because kids probably won't speak up

Dr. Sapossnek says, "Why would they? They think that's how everybody sees."

Eye doctors are also concerned about electronic devices, which can stress even healthy eyes.

Dan Hopkins, Sam's dad, knows his daughter gets a lot of screen time. In fact, a new survey says three out of four kids get three hours or more a day.

Dr. Sapossnek says everyone - young or old - who uses electronics or reads a lot should follow the 20-20-20 rule. That means, every 20 minutes you should look in the distance at something at least 20 feet away for 20 seconds.

A few other tell-tale signs of vision problems include:

-Covering one eye

-Tilting the head to one side

-Losing place often when reading

-Holding a book super close to the face

Again, all kids should have a comprehensive eye exam before heading back to the classroom.

They can see an optometrist or an ophthalmologist.