Now Sarah Richards is warning other party-goers to shun horror peeper-accessories as October 31st approaches.
Millions of Brits will dress up as ghosts, ghoulies, monsters and zombies at scare-season bashes next week.
But those who choose to change the colour of their eyes using lenses risk ulcers, tears on the cornea, infections and permanent sight damage.
It is not currently against the law for retailers to sell cosmetic lenses online in the UK.
It is, though, illegal for non-prescription lenses to be sold or supplied in Britain without the supervision of a registered optometrist, suitably qualified dispensing optician or medical practitioner.
That hasn't stopped illegal decorative lenses cropping-up for sale at market stalls and small general retailers all over the UK.
Some costing as little as £10 are available in fancy dress shops without any safety checks in place.
Sarah Richards, 24, bought a set of 'zombie' eyes with distinct white irises from such a store in her hometown Stratford-upon-Avon this time last year to attend a Halloween shindig.
Hours later she was in agony and unable to work for a week after developing a nasty eye infection.
The beauty therapist explained: "It was horrible.
"I bought the lenses for around £10 as a few of my friends were wearing them for the party too.
"As I've never worn contact lenses before, I didn't know how to put them in or what they should have felt like once they were sat on my eyes.
"All I remember was that they were made from quite thick plastic and they felt uncomfortable on my eyes straight away.
"But after a while it settled down and I assumed everything was okay."
Sarah doesn't know the brand of the lenses and admits she exacerbated the situation by sleeping in them - a definite no-no and rule well-known to regular contact lens wearers.
Sarah, though, knew no better as she'd purchased them outside the law.
She adds, "The next morning I woke up in absolutely agony.
"I knew it was the lenses causing me such discomfort and I had to physically prise my eyes apart.
"I could only see a tiny bit of light when I finally did open my eyes.
"I then had to scrape the lenses out. It was awful. And when I looked at them, they were covered in gunk and make up."
Unnerved and fearing she'd caused permanent damage to her eyes, Sarah went to an NHS drop-in centre and was given eye drops and an eye bath and told to avoid straining her eyes, using any make up, or wearing lenses.
Recalling her nightmare, she reveals: "They told me not to wear lenses - but there was no way I'd have had anything near my eyes at that moment in time anyway.
"My pupils were scratched and sore and just felt raw, like they had been covered in grit.
"Because I work in beauty, I could hardly treat clients with big red eyes and no make up on, so I had to have a week off work.
"I know I should have taken them out, but I'm sure there's a lot of people who go to Halloween parties, have a drink, and if they're not used to wearing contacts, they would do the same as I did.
"I would say to anyone thinking about novelty contact lenses to think twice - you need to be so careful and make sure you know what you're doing with them before they go anywhere near your face. "
For leading laser eye surgeon Dr David Allamby, Sarah's horror story is a huge worry, and he's urging the government to clamp down on novelty contact lens sales.
The world-renowned specialist, medical director at London's Focus Clinic, warned: "You wouldn't drive a car that didn't have an MoT - it'd be extremely dangerous and foolish to do so.
"Yet many people in the UK seem to think that putting things in their eyes that haven't been sold by a trained eye-care professional is perfectly fine.
"It is anything but.
"Decorative contact lenses need to be treated in the same way as prescription contact lenses - you need to have thorough guidance in how to use them along with a plan for follow-up care.
"The eye is a very delicate area and it needs to be treated as such.
"I have seen some terrible cases of injuries from normal contact lenses, and novelty ones aren't likely to be made of the same quality as those on prescription.
"Even just putting them in incorrectly can lead to tears on the cornea, and bacteria breeds behind the lens which can lead to ulcers and potentially blindness.
"After a party, people might sleep in them, which increases the likelihood of infection. They need to understand there is a risk of them permanently damaging their eyes.
"Which is why it's quite shocking that you can just pick these things up on the internet or in a fancy dress shop with no advice or aftercare."
The range of novelty contact lenses on offer in the UK is vast, ranging from simple colour changes to checkerboard patterns, animal irises, spider webs and yin yang designs.
But Dr Allamby adds: "Take the horror out of Halloween by ditching the novelty contact lenses. Otherwise you could be in for a truly terrifying evening."