Purchasing eyewear is increasingly moving from optometrist and optician offices to the Internet, as a growing number of online retailers offer prescription glasses for a fraction of in-store prices.

But Canadian optometrists are raising concerns about a lack of oversight linked to online glasses, and warn that eyewear that is manufactured or fitted improperly could lead to eyestrain, double vision, or headaches.

In less than a decade, the prevalence of buying prescription eyeglasses online has exploded, with the number Americans that have their glasses delivered directly to their door growing at more than 10 per cent per year since 2007.

There are no recent Canadian statistics but, anecdotally, it seems Canadians are increasingly looking online when it comes to shopping for their new prescription glasses.

Indeed, online retailers have made it easier for consumers to purchase what has traditionally been a highly customized product with a few simple clicks.

Glasses.com offers a try-on tool through its mobile app that uses your device’s camera to create a 3D model of your face to virtually view frames from any angle.

Meanwhile, trendy glasses designer Warby Parker offers a "home try-on" service that covers the shipping cost of five sample frames so customers can give them a try before making a final decision.

And then there's the price.

Canada's largest online glasses retailer, British Columbia-based Clearly Contacts, estimates that prescription glasses that run for $400 in optical stores can be purchased for $38 to $198 on their website.

If you've logged on to Facebook lately, you've likely spotted Clearly Contacts' 'First Pair Free' campaign, which was launched to attract customers that may be wary of purchasing prescription eyewear online.

But optometrists say a number of online vendors are not following the same checks and balances that a licensed professional would follow, and the product that you order online isn't always what's prescribed.

"Hopefully (the glasses) fit. Hopefully there's an accurate prescription, but those are questions that are not always being answered," Dr. Paul Geneau, president of the Canadian Association of Optometrists, told CTVNews.ca in a telephone interview from Ottawa.

Geneau pointed to two studies that looked at the accuracy of glasses purchased online.

A 2012 study out of the School of Optometry of the Université de Montréal examined 16 frames and 32 lenses that were purchased from online glasses retailers.

The researchers found that six of the lenses did not match the prescription and 13 of the 16 frames did not receive a passing grade in terms of fit.

"The public is not well served by online ordering sites for prescription glasses," the study concluded.

A 2011 study published in the journal Optometry that evaluated 154 online eyewear orders showed nearly half of the prescription glasses did not meet patients' “visual or physical needs.”

The study showed 28.6 per cent of the glasses contained at least one lens that failed a component of optical analysis.

The study noted that the majority of optical failures in the traditional dispensing model are identified during inspections before the glasses they leave the laboratory, so no more than two per cent of the prescriptions are returned after delivery.

Geneau said there are regulations on the dispensing of prescription glasses in every Canadian province except for British Columbia, where some aspects of dispensing eyewear were de-regulated a few years ago.

He said in the United States a prescription must be submitted to order glasses online, but that’s not the case in Canada.

"What sometimes happens is you want to avoid another eye exam. Sometimes the prescription is a bit outdated, or you think you'll be able to see better if the glasses are a little bit stronger," Geneau said. "You have the ability to modify those (prescription) numbers.”

Geneau says there's also concern about lenses being bought in bulk from outside of Canada.

"Quality control may be less stringent, because it’s not being overseen or monitored," he said.

Better ways to buy online

But optometrists recognize that online competition isn't going away anytime soon.

Geneau says while more and more Canadians are purchasing glasses online, he hopes human involvement isn't completely cut from the equation.

He recommends that licensed professional check prescription glasses purchased online – a service he said patients could expect to be charged a fee for.

"It's money well-spent," he said.

Geneau adds that more online vendors are working in conjunction with bricks-and-mortar stores.

A spokesperson for Clearly Contacts says this is an emerging trend in the e-commerce world.

"Companies that started online are now branching off into offline," said Chief Marketing Officer Braden Hoeppner.

Clearly Contacts has opened three storefronts, two in Vancouver and one in Toronto.

 Clearly Contacts lab "top-notch": spokesperson

As for concerns raised about the dispensing of prescription eyewear, Hoeppner says Cleary Contacts' Vancouver laboratory is "top-notch in the world."

"I'd encourage anybody who has that concern to definitely go get (your glasses) checked," he says.

"Our quality standards are extremely high, so I don't think there's a need to double check that we got the prescription right."

He said the company has a policy to refund customers if the glasses fit incorrectly.

"Ultimately it becomes a partnership with the doctor," Hoeppner added.

"Consumers like shopping online, they like to discover new products, they like to browse," he says. "If they ultimately buy from us, or whether they buy in stores, it's a discovery platform to see new glasses."