EnlargeGetty / Aurich Lawson

Unless youd like to keep the pirate look going, its best to avoid costume contact lenses this Halloween.

Like every October, health authorities and medical organizations want to remind you that the decorative, over-the-counter lenses are not only illegal, theyre also terrible for your eyes. And they're not telling tall tales. The lenses can cause infections, sores, scratches, vision-impairing scars, and even blindness. Its easy to find eye-related horror stories from people who turned to black-market lenses to change the color, shape, or look of their eyes (some lenses even add logos to your eyeballs).

Just on Tuesday, USA Today reported the case of a Cleveland woman who got decorative lenses stuck to her eyeballs. The lenses were supposed to turn her brown eyes blue but instead made them swollen and red. She had to have them removed in an emergency room.

Still, decorative lenses have proven incredibly popular. The color-contact-lens market has at times been valued at $300 million, accounting for 15% of the total market for contact lenses.

People tend to pick them up from street vendors, beauty salons, flea markets, and novelty shops. But selling them over the counter is actually illegal. Contact lenses are considered a medical device and are regulated as such by the Food and Drug Administration. Anyone buying them needs to have a prescription for the lenses.

The dodgy, black-market lenses often turn out be contaminated, irritating, or simply the wrong size for your eyeball, causing injuries. If theyre too small for your eye or dont allow enough air through, the lenses can cut off oxygen to the cornea—the clear surface of the eye. This corneal hypoxia can allow infections to fester as well as cause damage the corneal tissue.

And thats just one of many potential problems. Things get even more dicey when people fail to follow basic contact-care instructions—like cleaning them occasionally and not sleeping with them or sharing them (which can spread infections).

In a 2005 medical report, a team of eye doctors laid out 12 consecutive cases of people arriving in medical centers with severe eye problems after using decorative lenses. The cases range from mild to extreme.

Shiver me timbers

Patient 1 was a 16-year-old girl who showed up with eye pain and redness after wearing a colored lens. She admitted to sleeping with the lenses as well as sharing them with her younger brother. Doctors treated her with artificial tears and an antibiotic ointment, and her symptoms quickly improved.

Patient 12, on the other hand, was not so lucky. After buying cat-eye lenses at a flea market, the 26-year-old man developed a severe, painful infection called Acanthamoeba keratitis. The infection is caused by a free-living amoeba running rampant in the cornea, which can be blinding—as it was in this case. He ended up needing a corneal transplant, and three months afterwards his vision was still 20/200, which is considered legally blind.

Patient 11 also suffered permanent vision loss. The 39-year-old woman went to the doctor with pain, redness, and blurred vision in her left eye after buying colored lenses at a hair salon. Her ophthalmologist quickly spotted an ulcer in the center of her cornea, which was positive for the pathogenic bacteria Pseudomonas aeruginosa. She was admitted to the hospital for intensive antibiotic therapy. But two months later, her best corrected vision in the affected eye was only 20/50.

  • Patient 9, a 16-year-old girl who bought colored lenses at a flea market, had a central corneal ulcer positive for Staphylococcus aureus. Steinemann et al.
  • Patient 10, a 24-year-old man who bought colored lenses at a gas station, developed a Staphylococcus epidermidis infection. He suffered permanent vision loss and scarring after continuing to use the lenses. Steinemann et al.
  • Patient 11, a 39-year-old woman who bought colored lenses at a hair salon, had a Pseudomonas aeruginosa infection, corneal ulceration, and permanent vision loss. Read More – Source