Some six million older people in the UK risk losing their sight by not having a regular eye test, a report suggests.
The Royal National Institute of Blind People (RNIB) study of 5,000 over 60s found that 47% did not have an annual eye test.
The RNIB want the government to invest in a large-scale eye health awareness campaign that targets older people.
Comprehensive eye tests can detect conditions such as glaucoma, wet age-related macular degeneration and diabetic retinopathy, they say.
RNIB report author Barbara McLaughlan said: "Our message to people over 60 is simple: don't wait until you notice changes in your vision to visit your optician – get your eyes tested every year.
"An eye test will detect the early stages of a serious condition and could save your sight."
She added that while over 70% older people understand why it is important to have an eye test, this does not translate into actual numbers of people getting their eyes tested.
"It's too dangerous to leave an eye test until you notice something's wrong. Early-stage glaucoma, for example, has no symptoms and up to 40% of sight can be lost before you realise anything is wrong."