Mr Miller said one-in-five children he saw in his clinic had these issues.
"In the low socio-economic areas it can be as high as 50 per cent or more."
He said undiagnosed eye problems could lead to misdiagnosis of other issues.
"If they can't read they play the fool and muck about and get labelled with ADHD, are learning disabled, dyslexic and sometimes it is as simple as getting their eyesight right.
"We have a lot of people coming in who have been told they had a learning problem when it is actually an eye problem," Mr Miller said.
One of the the biggest issues with testing children's eyes in schools was that youngsters were told to look at a letter chart on the wall six metres away.
That had no relevance to how eyes focussed, pointed and co-ordinated at something about 15cm to 30cm away, he said.
Langford Callard Optometrists in Tauranga director and optometrist Celia Cutfield said the results of the study did not surprise her.
"We see some of them," she said.
"They have a screening programme early on. It catches a lot of them but not all of them."
Ms Cutfield said ideally children would get an eye check when they started school and every two years after that but she was realistic: "that's probably not going to happen in some of those low-decile areas".
Ms Cutfield said many parents did not know a community-services card enabled children to get a free eye test every year and funding towards glasses.
Long-sightedness and trouble with tracking were two of the issues that often went undetected, she said.
Tracking meant often skipping lines or not following the path of objects and glasses would not fix that but training could, Ms Cutfield said.
Problems with tracking could delay reading levels and make completing tasks slower, which could frustrate children and cause them to give up, she said.
More in-depth screenings when children started school could help solve such problems but that was a matter of funding, Ms Cutfield said.
No more tilting for Hope
Hope Edwards-Poad, 12, has had eye control problems since she was a baby.
Mother Carys Edwards said she knew something was wrong with her little girl when she was about three years old.
"I didn't realise it was her eyes, I thought it was her ears. When she would watch [a] DVD she would tilt her head sideways, I thought she was tilting her ear forward because she wasn't hearing properly."
Ms Edwards had Hope's ears tested but no problems were found.
By age 4, Hope was squinting in the sun and her mother was scared she had a tumour.
Two years later, it was discovered Hope's eyes were not working properly.
"I realised she had been seeing double vision the whole time ...
"They were two independent telescopes, imagine holding two telescopes [one to each eye] and not having them match up."
Hope learned to compensate by tilting her head. Hope's eyes also meant she could not track moving objects, or read a book without seeing double.
Hope's eyes were corrected with low strength glasses but vision training was needed to correct her vision long-term, which she now does with Visque Greerton.
