Yesterday's solar eclipse may have permanently damaged up to five per cent of viewers' eyes, according to an Australian eye expert.
Doctor Bill Glasson told newscom.au up to five out of every 100 people who watched yesterday's solar eclipse would have permanent eye damage.
"They will have a blind spot, or black spot, in the middle of their vision when they wake up," he said.
"If it persists for more than a day certainly it will have done some damage.
"Some may find they have a permanent burn scar on the back of the eyeball and visual loss for the rest of their life."
Thousands of New Zealanders looked to the sky yesterday morning as the moon crossed directly in front of the sun.
Auckland eye doctor Sarah Welch said anyone who watched the event with the naked eye could have damaged their retina.
"Because the eye focuses light onto the back of the eye, it can leave a little burn in the centre of the retina."
She had seen at least one patient today who believed they damaged their eyes yesterday.
Evidence of this happening during eclipses is "well-documented" and can have permanent repercussions, she said.
"The person would either find that they couldn't see properly or that they had a small patch of their central vision missing."
To avoid damage, it is best to use solar glasses or a pinhole, she said.
"It goes against a lot of natural reflexes to look directly at the sun."
Yet Welsh said it was "unlikely" five per cent of people suffered such burns.
"I'm not sure where he got that number from," she said.