The Royal National Institute of the Blind has issued a call for people in Scotland to take up free eye tests and prevent blindness in later life.
Many vision problems are said to be avoidable
It claimed a quarter of the Scottish population had probably not had an eye test in the last two years.
That figure included 90,000 diabetics who are at greater risk from blindness.
A report by the body found that the number of people in Scotland suffering from sight loss could double over the next 25 years.
Free eye tests are currently available for the elderly and children as well as people in certain risk groups.
The Scottish Executive has pledged that free eye tests for all will be available before the end of the year.
RNIB Scotland Director John Legg said: "People are losing their sight because of ignorance.
"It is bad enough when anyone loses their sight but it is completely unacceptable when their loss of sight is avoidable."
Currently, just under 200,000 people north of the border and two million people in the whole of Britain are blind or partially sighted, according to the charity.
But its report, entitled, Open Your Eyes, found that number could increase dramatically in years to come due to the ageing of the population and the growth of conditions like diabetes.
An estimated 25,000 people in Scotland have undiagnosed glaucoma and another 25,000 pensioners over the age of 75 suffer sight loss from cataracts, both of which are treatable conditions.
The body also revealed that about 25,000 people over 75 are living with poor vision simply because they fail to take an eye test and get new glasses.
Mr Legg added: "People will still suffer avoidable sight loss if they don't go for a regular eye test.
"We want the Scottish Executive to introduce clear and robust national standards for health and social care provision for people with sight loss regardless of where they live."