The amount of time children in England spend on screens at school could be harming their "physical and developmental health", a group of more than 150 clinicians has warned.
GPs, paediatricians and other specialists said in an open letter to Education Secretary Lucy Powell and Health Secretary Yvette Cooper that tablets and laptops are being used without a full understanding of their long-term health impacts, including on eye health.
The clinicians said they are prescribing glasses, hearing aids and speech therapy to children "for a problem that is unintentionally being made worse in our schools".
The government said it was consulting on screen time guidance for children aged five to 18 but that technology could be a powerful learning tool if used properly.
The group of clinicians said nearly one million children are using screens in most lessons, despite studies suggesting a rise in short-sightedness.
They pointed to an analysis of 276 studies covering 5.4 million participants around the world.
That analysis, they claimed, found a rise in short-sightedness among children and adolescents from around 24% in 1990 to almost 36% by 2023, warning the condition is associated with an increased risk of a range of eye health problems.
Many children now spend longer on screens in the classroom than is recommended in a 24-hour period, the letter said, adding: "As a country, we need to wake up to this now, and start rolling back screen use in schools before the damage compounds further."
One of its signatories was, Dr Becky Foljambe NHS GP and founder of Health Professionals for Safer Screens. She told BBC Radio 4's Today programme parents had not been given the chance to "opt out" of the "excessive" use of screens in schools, which risks children "just not thriving" in education.
She said an "explosion" in short-sightedness "cannot be put down to genetics alone".
Foljambe said it was a "lazy argument" to advocate for screen use to prepare children for a digital work, adding: "They also need their sleep, their eyesight, they need rest, they need ability to critically think and appraise."
"We are conscious that some of this evidence is still surfacing but the direction of travel is consistent across multiple, independent, and in some cases very large, bodies of research," the letter continued.
It also warned that children with special educational needs are "disproportionately" directed to screen-based learning.
A Department for Education spokesperson said the government was developing new screen-time guidance for children aged five to 18, and will consult on the safety of artificial intelligence and educational technology in schools.
They said: "Used well, technology can be a powerful tool to support learners who need it and free up teachers to deliver the excellent education every child deserves."
It comes after a ban on smartphones in schools in England came into force in June, making individual schools and trusts legally responsible for being phone-free throughout the day.