Doctors have warned of the dangers of Nerf guns - after a spike in eye injuries.
The soft bullets fired from the toy guns can lead to internal bleeding around the eye as well as blurred vision, experts said.
Protective eye goggles should be worn and the age limit for Nerf guns - currently set at eight years old - should be reconsidered, medics suggested.
It comes after A&E doctors at the UK's leading eye hospital treated three patients who suffered internal bleeding from the guns.
The child complained of pain and blurred vision.
He developed swelling of the outer layer of the eye (cornea), and the inner layer of the eye (retina), from the force and speed of the bullet fired by the gun.
- A 32-year-old man suffered blurred vision and a red eye after being shot from eight metres away by a child with a Nerf gun
- A 43-year-old woman was shot in her right eye from a distance of one metre and complained of blurred vision and a red, sore eye
- An 11-year-old child suffered pain, swelling and blurred vision after being shot in his right eye from a distance of two metres
All the patients were examined and given eye drops.
But while there was a good outcome for these patients, experts said the ability of Nerf guns to cause problems was worrying and could lead to long-term vision loss.
"This case series emphasises the seriousness of ocular injury from Nerf gun projectiles and calls into consideration the need for protective eyewear with their use," researchers from Moorfield's Eye Hospital in London said.
"It also calls for reconsideration of the safe age limits for Nerf gun use in children."
The research, published in the British Medical Journal (BMJ), also pointed out that one patient had told them that non-branded, cheaper bullets that fit Nerf guns are on sale.
Examination of these bullets showed them to be harder than the ones made by Nerf gun manufacturer Hasbro - something parents may not be aware of.
Numerous online videos also show children how to modify their guns to make them shoot harder, faster and further distances.
Medics said that no safe distance for avoidance of significant eye trauma can be established from the cases seen.
A spokeswoman for Hasbro said: "Product safety is of utmost concern at Hasbro.
"Nerf products are designed based on years of consumer insights and research and undergo rigorous reviews and testing to assure that they are safe and fun to play with and meet or exceed global standards and regulations.
"Nerf foam darts and foam rounds are not hazardous when used properly.
"Consumers must never aim Nerf blasters at a person's eyes or face, should only use the foam darts and foam rounds designed for specific Nerf blasters and never modify darts or blasters."