People are risking their vision because they can't afford eye tests and new glasses, experts have warned.
Optometrists say patients are choosing not to update their prescriptions - despite needing vision correction - because of the cost of switching their lenses.
Other patients say they are turning to pound shop 'ready reader' glasses in order to cut down their costs, according to the Association of Optometrists (AOP).
They warn that those people who are not updating their prescriptions could be putting the long-term health of their eyes at risk.
It comes as households across the UK face a cost of living crisis, with soaring inflation prompted by rising gas and electricity bills and an increase in the costs of supermarket shops.
An AOP survey of 876 optometrists found seven in 10 had seen a patient in the last three months who needed vision correction but took no action because they could not afford to.
The association also conducted a new poll of 1,000 British adults and found 62% who wear glasses or contact lenses say they are currently "putting off" paying for suitable vision correction due to the crisis.
Of those surveyed, 36% said they were wearing out-of-date prescriptions, while 19% use glasses they have had to fix themselves.
Others who took part in the survey told the AOP: "Although my sight is very important, so is feeding my children."
Another said: "At the moment, I have a pair of reading glasses from the pound shop because I don't have any spare money to get an eye test and new glasses.
"And I know that they are not correct for my vision and I have to strain my eyes to read properly."
People can claim vouchers to help with the costs of glasses through an NHS scheme.
However, the scheme is only available to specific groups, including children and people who qualify for means-tested benefits.
Adam Sampson, AOP chief executive, said: "It's of deep concern that people are being forced to make decent vision an optional extra.
"The stories to come out of this research are truly shocking and it's imperative that action is taken now to minimise the long-term damage to people's eyesight.
"Help is available to those who need it but the NHS optical voucher is out of step with inflation - and like many essentials, people are being forced to go without.
"A simple yet effective way of ensuring people get the vital eye health checks they need and we don't hit an eye health crisis later down the line is increasing the NHS voucher now to help people offset against rising costs.
"Doing nothing quite literally risks the vision of the nation and may end up costing much more."