Andrew Hogan of Optometry Australia sees a lot of children in his practice in Hobart, often when parents or teachers notice one of those symptoms.
"Kids won't complain about blurry vision," he told Helen Shield on ABC Radio Hobart.
"Kids who aren't paying attention [in class], sometimes it's simply because they can't see and they don't realise that everyone else can see, because they've got nothing to compare it to."
Mr Hogan said long-sightedness was quite common in children, making it hard for them to focus on things up close.
"[A] long-sighted kid will get really close to the television, even though that technically makes it harder for them to see, but it makes it bigger," he said.
"Kids' behaviour is often the opposite of what you'd see in an adult with a similar problem."
Tests before school starts?
Mr Hogan said he preferred to see children for an eye test a few weeks after school had started, as problems can often only become apparent as kids' school work gets harder.
"[As they go up a grade in school] they're going to be writing more, they're going to be reading more, they're going to be using their eyes more," Mr Hogan said.
"Often a problem that hasn't caused any symptoms up until now can suddenly start, so those first few weeks of school is often when we see parents bringing kids in."
While parents may have bad memories of ugly reading glasses when they were kids, Mr Hogan said most of the children he sees want to wear glasses.
Along with keeping a watchful eye on your child's eyesight and associated behaviour, protecting their eyes from UV exposure was also recommended.
"There's literally nothing bad about sunglasses," Mr Hogan said.
"We know that of all the controllable factors the one thing you can do to protect your eyes is block out UV light. And that's what sunglasses do.
"Most people see more comfortably on a bright day if they're wearing sunglasses and kids are no different."
Mr Hogan said there was no need to go with expensive brands of sunglasses for kids as novelty-looking ones can perform just fine.
"There are plenty of sunglasses for kids that do not have to be expensive," he said.
"Because a valid argument is, 'they're going to break them or lose them'.
"My son loses jumpers at a rate that you wouldn't believe, but he's never lost his Batman sunglasses."