The move follows evidence put before MSPs this month which showed that thousands of pre-school children were not being screened for eye defects and diseases - and that many school-aged children later showed undetected eye defects.

According to a survey by Glasgow Caledonian University’s department of vision sciences, three-quarters of nursery-aged children do not have their eyes tested by an orthoptics expert or an optometrist.

In a postcode lottery of provision, children were being tested in Bearsden and Milngavie and not in Easterhouse and Dennistoun. Aberdeen and Dundee tested but not Edinburgh, Aberdeenshire and Angus. In North and South Lanarkshire, only 10 per cent were being tested.

Pre-school screening can detect lazy eye (amblyopia), which if untreated at an early age is incurable. As a child grows other refractory errors such as short and long sightedness and binocular vision become more apparent. Screening can also detect systemic diseases.

Frank Munro, a Glasgow optometrist and president of the College of Optometrists, said: “The screening system is failing in Scotland and the UK as a whole.”

Tom Lowe, senior educational psychologist in North Lanarkshire and a spokesman for the Association of Scottish Principal Educational Psychologists, said: “It cannot be assumed a child will be aware they are not seeing properly. If visual defects are missed, children will struggle to learn and to enjoy play at a time when both are critical to their development.”

A screening committee in the Department of Health, on which the Scottish Executive is represented, is currently considering a proposal for universal screening but this would only apply to the pre-school group and would have to be delivered by orthoptists, of which there are only 40 in Scotland.

The cross-party group is considering proposals to screen children at age seven and 11, as well as at the pre-school stage. Mike Cairns, chief executive of the Royal National Institute for the Blind in Scotland, said:

“Universal testing needs to be introduced on a more extensive basis than simply pre-school screening.”

Kate MacLean, the Dundee MSP who chairs the parliamentary group, declared:

“Given that 20 per cent of children have undetected eye problems which could affect their education, we need to do something quickly.”

The cross-party group is to consider a range of models for screening - either on site in schools or through optometrists.

David Eaglesham, general secretary of the Scottish Secondary Teachers’

Association, said: “In the interests of social inclusion the tests should be carried out in schools.”