The Royal National Institute of Blind People Scotland (RNIB) said the pandemic has led to delays in people receiving treatment which could have stopped damage to their vision.
There were 700,000 fewer eye examinations in 2020-21 than the previous financial year, figures from Public Health Scotland show – a drop of just under a third.
RNIB said it fears some people will “inevitably” have lost sight that might previously have been prevented.
Director James Adams said eye care services must be made “as streamlined and effective” as possible.
RNIB is one of several charities hosting a conference on Wednesday to discuss care backlogs and sight loss in Scotland.
Bruce Christie, 56, from Aberdeenshire, who experienced sight loss at the age of 36, will call for more support for others.
"We're talking about the loss of one of the five senses - and the profound effect that can have on one's life - so I do think some form of ongoing support should be available," he said.
"Try walking around your house with your eyes shut. Try cooking and chopping vegetables when you can't see what you're doing. Just pouring water into a glass is a very real challenge for me because my depth perception is limited now.
"It's surely easier and more effective to deal with someone in the early stages of learning how to live with their sight loss, than later with someone who may be suicidal because of it. And while that may sound dramatic, it is a very real possibility."
A Scottish Government spokesperson said regular eye examinations are essential, and urged anyone who suspects something may be wrong with their vision to contact their local option to arrange a free appointment.
They added: “As Covid-19 restrictions have eased, the number of NHS-funded eye examinations now being undertaken has mostly recovered to near pre-pandemic levels.
"This is despite ongoing infection prevention and control measures being in place.”
The RNIB helpline for those affected by sight loss can be reached on 0303 123 9999.