'The eyes can be a window to your general health'

Optometrists, the professionals who perform eye tests, can detect a range of conditions, not all as mild as short-sightedness or as serious as a brain tumour.

Among them is glaucoma, which can cause blindness if left untreated. It occurs when drainage tubes in the eyes become partially blocked and, while damage already been done cannot be cured, early detection and treatment can prevent further damage and sight loss. Eye tests - free on the NHS in Scotland - can also reveal signs of diabetes and of macular degeneration, a painless eye condition that leads to the gradual loss of central vision.

Optometrist Jennifer Paterson said: "An eye exam can show us much more than whether or not someone needs glasses. The eyes can be a window to your general health and can warn of other conditions, including diabetes and, in a small number of cases, more serious issues like Kerri's."