Optometry Australia is warning about the dangers of wearing novelty contact lenses for Halloween.

Creepy clowns are not the only things fancy-dress enthusiasts should be wary of on Halloween - novelty contact lenses can be dangerous, too.

Optometry Australia warns that non-prescription accessory lenses can lead to long-term eye damage.

They can result in infections and even permanent blindness, optometrist Simon Hanna says.

"The surface of the eye is extremely delicate and wearing non-prescribed novelty contact lenses, particularly those from a dubious source, could cause eye damage ranging from mild infections to sight-threatening conditions such as corneal scarring and even blindness," he said.

Mr Hanna said if people wanted to enhance their Halloween look with fancy-dress lenses, they should make sure the lenses were prescribed by an optometrist, who could measure each eye to properly fit the lenses.

People should also always wash their hands before touching contacts and take the lenses out before going to sleep.

They should seek medical attention if their eyes become red, sensitive to light or their vision becomes blurred.