Age UK and the College of Optometrists say too few request the free check-ups offered to those aged above 60.
An Age UK poll of 1,700 suggests one in seven over-60s, nearly two million, has not been tested for at least two years.
Nearly four million are estimated to have fallen in the past two years, and the poll indicated one in 14 of these falls was linked to vision problems.
Falls are the leading cause of death through injury in the elderly.
Helena Herlots, of Age UK, said: “It’s worrying that such a high number of older people have not had a sight test recently.
“Going for regular sight tests and wearing the right glasses will not only improve balance, co-ordination and mobility, but will help to maintain general eye health.”
Dr Anna Kwartz, of the College of Optometrists, said: “Many of the visual problems that affect older people and lead to falls can be treated.
“Regular sight tests can help aid early detection and treatment.”