Why DOES your sight get worse with age?

It starts with blind spots at the edge of your vision that you won't notice, progressing to tunnel vision and sight loss, which can take up to five or six years to become apparent, says Gus Gazzard, a consultant ophthalmic surgeon at Moorfields Eye Hospital, London.

Up to half a million Britons have a degree of sight loss due to glaucoma. 'Most cases are picked up by opticians, but there's a high rate of under-diagnosis.' It's easy to miss when it is caused not by pressure in the eye, but as a result of problems with blood flow.

Risk factors: Family history, ethnic group (Afro-Caribbean, Indian and Chinese people are more at risk) and increasing age are the biggest risk factors. Regular sight tests will detect it early and treatments can prevent further damage.

Treatments: Traditionally, it is treated with eye drops (one to four times a day) that reduce fluid production or increase its flow out from the eye.

But they can be unpleasant to use and potential side-effects include sleep problems and impotence.

A new ten-minute procedure, selective laser trabeculoplasty, effectively causes a minor injury to the eye, drawing white blood cells to the area. These clear the blockage as they repair the damage. This is offered on the NHS. Moorfields is running a trial comparing it against eyedrops.

Between 10 to 20 per cent of patients need surgery. With the standard operation, trabeculectomy, a channel is made in the white of the eye so fluid can drain out. Lasers can also open up the blocked drainage tubes. There is a risk of scarring preventing fluid flow.

With the latest surgery, a device called a trabectome destroys blocked tubes with an electrical impulse. The procedure, which has a small risk of bleeding, is available only at Moorfields, Musgrove Park Hospital, Taunton and the Royal Hallamshire Hospital, Sheffield.

(dailymail.co.uk)