With Halloween around the corner, many will be kicking off the spooky celebrations this weekend.
Whether dressing as a cat, channeling Edward Cullen from Twilight or going corpse bride, more and more are turning to scary contact lenses to complete their dramatic look.
But experts warn buying coloured contacts from “rogue traders” could put you at risk of everything from infections and eye ulcers to severe pain and even blindness.
Yahoo UK looks at the risks of Halloween lenses and how to use them safely.
The internet is awash with different Halloween contact lenses, with products starting at just £2.99 ($3.83).
Clicking “add to basket” may be the easy option, but Specsavers warns contacts lenses that have not been properly fitted by an eyecare professional can cause serious damage.
While some endure blurry vision, redness and conjunctivitis, better known as “pink eye”, others suffer infections or allergic reactions.
The misfitting lenses can also scratch the cornea or cause it to swell. The cornea is the clear layer that covers the coloured iris and protects the pupil.
With the cornea having a rich nerve supply, even small abrasions can be very painful, according to Moorfields Eye Hospital.
While symptoms usually clear up, infections and scratches can trigger eye ulcers.
Left untreated, these can progress and cause pus to accumulate in the anterior chamber, the fluid-filled space between the iris and cornea, ophthalmologist Dr Rajeev Gupta told lybrate.com.
If the infection spreads to the inner eye, it can result in total blindness, Dr Gupta warns.
And if a deepening ulcer pierces the cornea, a large amount of pus, or even the entire eyeball, may need to be removed, he added.
“We’d never want to rain on your Halloween parade [but] sometimes zombie contact lenses to go with your zombie bride ensemble just isn’t worth the risk,” Specsavers’ website states.
All coloured contact lenses supplied in the UK, including those without a prescription, are classed as a medical device. They should therefore only be supplied or overseen by a registered optician.
Despite this legislation, many “rogue traders” push cat-like contacts online around the spooky season.
“The past few years have seen the rise of rogue traders looking to make a profit on those looking for a cheaper option or simply aren’t aware of the dangers of cheap lenses,” Ashish Mathur, eyecare specialist at Feel Good Contacts, told Yahoo UK.
“Margins are being squeezed for mass production and quality, with care and the risk of infection suffering as a result. The novelty lenses commonly stocked in high street corner shops are highly unlikely to have passed the same levels of safety standards reputable contact lens manufacturers are required to abide by.
“Those flirting with these low cost lenses and not properly checking where they are being manufactured are taking serious risks with their eye health and I encourage people to think carefully before making a purchase.”
How to buy Halloween contact lenses safely
Vision Direct recommends people go to their optician for a prescription, even if they have perfect eyesight.
High street stores like Specsavers and Vision Express, where you can normally buy contacts, do not stock Halloween lenses.
Partygoers should therefore find sites that match lenses to the individual’s prescription. This seems to be no mean feat.
Specsavers also recommends people look out for the “CE” mark on packaging, which shows the product meets health and safety protection standards.
After buying the “real deal”, Mr Mathur stresses they must be used and cared for in the same way as regular lenses.
“When applying and removing your contact lenses, you must always follow good hand hygiene practices,” he said.
“Before inserting your lenses, wash your hands thoroughly with soap and water and dry them with a lint-free towel. Before removing your contact lenses, wash your hands again before taking removing them from your eyes.
“[And] if you plan on wearing your Halloween contact lenses after Halloween, or multiple times leading up to the day, make sure to store them properly in fresh contact lens solution and a clean contact lens case.”
For those not used to wearing contacts, it may be easy to go to bed with them still in, particularly after a few seasonal cocktails.
“Make sure to set a reminder if you think you may forget to take them out before you fall asleep as leaving them in overnight can cause serious irritation or infection, and they can be a nightmare to get out the following morning,” Mr Mathur said.
Feel Good Contacts also recommends people remove their lenses before their make-up, do not rub their eyes while wearing contacts and take them out if they experience any discomfort.