Laser eye treatment has become increasingly popular since the first operation was carried out on a human eye just over twenty years ago. Just like contact lenses, laser eye surgery can often be used to treat three common refractive – or focussing – problems with the eyes. Short-sightedness (myopia), long sightedness (hyperopia), and astigmatism, the condition where the cornea is an oval, rather than round shape, are still widely treated through the use of contact lenses. Successful laser eye treatment for these common conditions can remove the need to wear contact lenses in certain circumstances, but just how does this treatment work?
Refractive problems with the eyes can perhaps be best understood by considering the way that the cornea and lens in the eye focus light on the retina at the back of the eye. In simple terms, the light sensitive cells in the retina carry out a similar function to the film in a camera. If the cornea is curved too steeply, light can be focussed in front, rather than on the surface of the retina, causing short sightedness or blurred distance vision. Alternatively, if the cornea has too shallow a curve, the focal point for the light collected by the eye can be behind the retina, causing long sightedness, or an inability to focus on nearby objects. In astigmatism, the oval rather than round shape of the cornea produces two different focal points, and vision at all ranges can be blurred.
Laser eye treatment can be used to change the shape of both the cornea and the eye lens to correct all three problems. The most popular form of the treatment is LASIK (laser in situ keratomileusis), where a very thin flap is cut on the surface of the cornea, which is moved back to expose the tissue underneath so that the laser treatment can be applied to vaporise selected cells. Due to the extremely focused nature of the heat produced by the laser, only the small targeted area that needs alteration is affected, with surrounding tissue left unharmed. This fact, and the healing properties of the cornea means that when the flap is replaced it heals very quickly, and in fact both eyes can usually be treated in the same day.
Laser eye surgery can also be used to treat diabetic retinopathy, problems with the lens capsule after cataract surgery, and certain forms of wet macular degeneration, as well as some diseases of the cornea.