Some optometrists are reporting a spike in calls from people who looked at the sun during Monday's solar eclipse.

Dr. Kevin Mowbray at the Mount Pleasant Optometry clinic in Vancouver says his office got between 10 and 20 calls from people concerned they had damaged their vision.

Mowbray says even just glancing at the sun during a partial eclipse can cause some permanent loss of vision, which an eye exam can reveal.

"They can come in for a regular eye exam and on top of that we can do a visual field test to see if they're missing little tiny holes in their vision, which is all anyone would lose."

He says of the patients who came in yesterday, none suffered vision loss.

"You don't go completely blind, but you do get little blind spots called scotomas."

eclipse ottawa

A woman wears solar glasses while enjoying the partial eclipse in Ottawa on Monday. (Sean Kilpatrick/Canadian Press)

Even a glance

According to UBC radiation safety expert Craig Smith, who teaches radiation biophysics, even a quick glance at the sun is never safe, particularly during an eclipse.

"Anything greater than a quarter of a second — that's where the damage begins," says Smith.

Looking at the sun during an eclipse causes irreversible damage of the area of the eye called the retina, and a specific area of the retina called the fovea, he notes.

"That is the part of the eye we use for things like reading. You focus on the computer screen and you see the detail.

"What happens in an eclipse if you were to look at the sun is you get an incredibly intense focus on a very small area of the fovea. The image of the sun is less than a millimetre on the fovea and we end up with permanent damage to those cells. And once those cells are damaged you can't see."

'You will always have that scar'

Animals have a natural aversion to looking at bright lights like the sun that protects them, he notes. But curious people may be tempted to override that natural aversion.

Pin hole box for solar eclipse

Many people made pinhole boxes to watch projections of the eclipse. (David Horemans/CBC)

"That's when you get the consequence. The effects on vision will be instantaneous.

"They will start to notice a lack of colour. Immediately everything will appear to be bleached out, and depending on how long they were looking at the sun, there will be a profound loss of the ability to actually focus on anything."

Depending on the duration of the exposure the consequences could be permanent.

"There will be an initial damage that will resolve somewhat, but you will always have that scar."

Smith notes the long-term consequences also include macular degeneration and cataracts, which can cause further loss of vision later in life.

eclipse welders mask

Welding masks are the order of the day at Vancouver's H.R. MacMillan Space Centre. (Tina Lovgreen/CBC)