Directing lasers at a cockpit could have "devastating" consequences, leading eye specialists have said.
Handheld lasers which are pointed at a plane or a helicopter can "dazzle" pilots who "almost certainly will be distracted", they said.
See also: Flying instructor blinded by laser
See also: Laser attacks mid-air are an unnerving experience, says pilot
If pilots are distracted at a critical time, such as during landing, the result could be disastrous, according to their editorial published in the British Journal of Ophthalmology.
The number of incidents of people pointing lasers at aircraft is on the increase, said Professor John Marshall of the Institute of Ophthalmology at University College London, John O'Hagan who is head of the Laser and Optical Radiation Dosimetry Group at Public Health England and John Tyrer, professor of optical instrumentation at Loughborough University.
In the UK there have been more than 1,500 cases of lasers directed at aircraft in the last year, they say.
In February a Virgin Atlantic flight to New York JFK was forced to return to Heathrow as a ''precautionary measure'' after a laser was shone at the cockpit.
Just nine days later a British Airways service from Amsterdam was affected when a beam was aimed at the aircraft as it headed towards Heathrow.
But there is no evidence to suggest that t lasers pointed at cockpits damage pilots' eyesight, the experts said.
There has only been one case of alleged retinal damage in a pilot as a result of laser targeting of aircraft, they said, but the "suspect" case is questionable because of the distances involved.
When the incidents occur the distance between the source of the laser is usually hundreds to thousands of metres. And the lasers also need to penetrate the cockpit windshield, but because these are usually scratched they would "scatter" the beam of the laser, they said.
"In this situation, the systems are operating over a long range - typically hundreds to thousands of metres and the laser beam has to pass through the atmosphere before traversing a cockpit canopy or windshield," they wrote.
"These are usually pitted or scratched and will serve to scatter the primary beam and may result in the generation of secondary and tertiary beams.
"In these situations, pilots tend to self-focus on a sudden bright light in the cockpit environment and may be dazzled, resulting in an after-image and almost certainly will be distracted.
"Obviously, if such a distraction occurs at a critical time such as during landing then the result could be devastating. Fortunately, these exposures are at irradiances that are incapable of producing irreversible retinal damage even at distances of 100m."
Between half and one million laser pointers, pens, and keyrings are thought to have been in circulation over the past decade, they said.
In the last eight years the "nature and supply" of handheld devices have changed dramatically.
In the past, many commercially available pointers are Class 2 laser products - which are not really strong enough to cause extreme damage because they do not have sufficient energy to pass into the eye before the targeted person blinks and turns their head away.
But many of the devices are now stronger and can cause serious damage, the experts warned.
Some are being mislabelled and should be classified as Class 3B laser products - which are not suitable for sale to the general public.
Some Class 4 devices are available online and are "capable of causing irreversible retinal damage if directed into the eye over short ranges".
Around 150 children in the UK are thought to have lost their central field vision as a result of these devices, they said.
Commenting on the editorial, Stephen Landells, flight safety specialist at the British Airline Pilots' Association (BALPA), said: "People need to realise that shining a laser at an aircraft endangers the passengers, the crew and people on the ground.
"Pilots understand there are some important uses for lasers but can't see any good reason why people should be allowed to carry one when there is no obvious purpose for doing so.
"BALPA has called for all but the lowest-powered lasers to be restricted and wants them recognised in law as potential weapons in the same way knives are. This would mean police would have improved powers to search people they suspect are carrying a laser, confiscate it and arrest them unless they have a good reason for having it."