Laser eye surgery is a term that refers to a range of procedures designed to correct the focus of the eye, so that spectacles and contact lenses are no longer required. It includes LASIK, LASEK, and PRK. The laser is used to reshape the surface of the eye at the cornea.

HOW LASERS RESHAPE THE CORNEA

Myopia: In short- sightedness, where the curvature of the eye is too steep, the cornea is flattened by removing more tissue from the centre than the edge.

Hyperopia: In long-sightedness, the curvature of the eye is too flat, so the intent is to create a 'bulge' forward in the centre of the cornea to make it steeper. The laser does this by removing a ring of corneal tissue around the edge. The effect shrinks the cornea, which in turn leads to the central cornea bulging forward and steepening - almost like pulling the string tight on a drawstring bag. This technique is difficult to perform well, and the bulging might not be or regular, which can affect the results of surgery.

Astigmatism: In astigmatism, the different curves on the surface of the eye have to be 'smoothed' out.

In general, corneal laser surgery can treat high short-sightedness and only moderate long-sightedness. Any form of corneal surgery can cause clouding or distortion of vision, and this may reduce the overall quality of vision.

GOVERNMENT OPINION

The National Institute for Clinical Excellence (NICE) report concluded that LASIK was effective in selected patients with mild or moderate short-sightedness, but the evidence was less conclusive in long-sighted and severely short-sighted people. Concerns were raised about the safety of the procedure in the long term, which was not adequate to support its routine use in the NHS.