Women who long for lush lashes have had to rely on messy mascara and fussy false lashes. Now, doctors have stumbled on a new treatment from an unexpected source: a glaucoma drug.

The drug is called Lumigan. For glaucoma patients, the medication reduces pressure inside the eye. But it also appears to make lashes thicker by increasing the growth cycle of hair follicles and slowing down how fast they fall out.

The drug seems to offer this unexpected side effect because it's made with prostaglandins, hormone-like substances that flourish during a woman's pregnancy and can make her hair thicker.

Now, Vancouver husband wife team Drs. Jean & Alastair Carruthers, an ophthalmologist and a dermatologist, are studying the medication. They say that in their tests, they found that people grew lashes that were about 50 per cent longer and twice as thick. The lashes were also 18 per cent darker - all of this without the need for mascara.

"We've never had anything that could grow eyelashes before," Dr. Alastair Carruthers told CTV.

Jean Carruthers even tried the medication herself.

"I was getting comments like 'Your lashes look great,' something I had not heard before," she says.

Sheryl Myers is one of the patients who has helped test the medication as a lash builder. She says she used it nightly for three months, applying it along the skin at the base of the upper eyelashes where the eyelashes meet the skin.

Within two months, she was ready to throw away her mascara for good.

"There were marked results... I would say significant,' she says. "If I applied mascara, they would hit my glasses. They were long -- really long."

"I'm like, 'Oh my god I hope they don't grow any more!'" she laughs. "It was strange... in a good way."

This is, of course, not the first serendipitous discovery of a new use for an old drug. The baldness-fighter Rogaine started out as a blood pressure drug, for example. And the superstar wrinkle-fighter Botox was first a drug to treat eyelid spasms and other neuromuscular problems.

The Lumigan treatment is not without potential side effects. Studies have found that it can make eyes red and itchy in four per cent of people. And because prostaglandins affect skin pigment, they can darken the skin around the eye. In rare cases, it's darkened a patient's natural eye colour, especially in people with light-colored eyes, though the Canadian researchers have yet to see that in their tests.

The drug works only for as long as it's used. One it's discontinued, eyelashes will gradually return to the length they were prior to treatment.

Lumigan's manufacturer even warns on its website that "darkening of eye color is likely to be permanent" and "The effects of increased darkening beyond five years are not known."

Ophthalmologists say that people with certain eye conditions shouldn't use prostaglandins. They include individuals with previous eye inflammation, or uveitis. People who have recently had cataract surgery and developed inflammation in their retina afterwards should also avoid these drops.

The drug has just been approved by the FDA in the United States as a lash builder, and will be sold by prescription only under the name Latisse.

It hasn't been approved for cosmetic used yet in Canada, as studies are ongoing.