Watchdog Healthcheck
BBC Online
July 12, 1999

New scientific research from Germany shows that seven out of ten patients are left with defective vision after laser surgery.

Poor night vision is caused by the eye's inability to respond quickly enough to changing levels of light, causing glare, ghosting, halos and starbursts. This is corrected in jost patients by glasses. However, if you've had laser surgery, the condition may be untreatable.

At Hertfordshire Police HQ, Louise Mahon answers 999 calls. She wanted to be a policewoman but her eyesight wasn't good enough. Louise hoped laser surgery would get her into the Police Force but, by the time she had the procedure, it was too late. The Home Office had issued new guidelines that no one who has had laser surgery should join the police.

It is not just the Police Force who have adopted these rules. The Fire Brigade and the Civil Aviation Authority have also decided not to recruit laser eye patients. The CAA says "laser procedures may produce side effects of glare and distortion of vision .... the long-term effects are unknown and laser surgery is not recommended for aircrew."

Consultant ophthalmologist, William Jory, also has reservations. He used to perform laser surgery until he heard worrying research presented at international scientific meetings. He says: "I have been able to demonstrate a loss of night vision in my laser cases, not all of them but a majority, approximately 80 per cent." When the reports of night vision loss were confirmed, William Jory stopped using the laser for the treatment of shortsight.

In Germany if you have a car accident at night, you may be required to sit a night vision test. If you fail it, under German law, you'll be held responsible for the accident.

The experimental ophthalmology department at the University of Tubingen Eye Hospital has been carrying out tests on post-operative laser patients for nearly 10 years. Its latest findings show that, despite improvements in technology, over 70 % of patients are still failing the contrast test This means it is difficult to make out objects at night, and 50% are failing what's known as the mesometre test. That means under Germany law they are unfit to drive.

In Britain there's no night vision test for drivers, so Healthcheck brought people who've had laser surgery to the Transport Research Laboratory in Berkshire for sight and driving tests. Our volunteers took two simple sight tests. First the contrast test - a variation on the traditional sight test, except it measures how well you can pick out objects in the dark. With good night vision you should see 9 lines of letters. If your night vision is poor, you'll have difficulty with the last few lines, and that means your night vision is affected.

Optometrist Nigel Burnett Hod found that jost of our volunteers had problems with those bottom lines. For Healthcheck he devised a special glare test. He found that, among nine people that represent a successful group of laser patients, two thirds of them do have slight night vision problems - a little bit of flare, glare and hazing.

So what was their driving like after midnight on a rural road? The volunteers had to read two signs. Drivers who had not had laser surgery read them at 55 metres. But four out of five who had the surgery scored much worse.

In line with German research, jost of those we tested had defective night vision. It may have been poor before surgery, but the lasers hadn't corrected it. In some jobs and road situations, poor night vision could be disastrous.