All eye surgery is carried out under local anaesthetic, given as eyedrops. It is an outpatient procedure that takes just a few minutes to perform. Patients are typically able to return to their daily routines within one to three days - if all goes according to plan.

Before the procedure begins, the patient’s eye is measured to determine the degree of visual problem, and a map of the eye’s surface is constructed. The required corneal change is calculated based on this information, and is then entered into the laser’s computer.

Patients who elect for LASIK surgery rarely feel pain during the procedure. The doctor will have you lie down, then make sure the eye is directly under the laser. (One eye is operated on at a time.) A kind of retainer is placed over your eye to keep your eyelids open. This has a suction ring that keeps your eye pressurised, which is important in LASIK for allowing the surgeon to cut the corneal flap. The surgeon uses an ink marker to indicate where the flap should be. The cut is then made with the microkeratome. During the procedure, you won’t see the flap being cut as it is very thin.

The surgeon uses a computer to adjust the laser to your particular prescription. You will be asked to look at a target light for a short time while he/ she watches your eye through a microscope and the laser sends pulses of light to your cornea. With some lasers, it is critical that your eye remains fixated on the target light to obtain the best results. Other lasers are equipped with a special tracking device that follows your eye even if it moves.

The laser light-pulses will then painlessly remove tissue. You’ll hear a steady clicking sound when the laser is in operation. You’re also likely to smell a mildly acrid odour from the tissue being removed. The higher your prescription, the more time the operation takes. The surgeon has full control of the laser and can turn it off at any time.

When the procedure is finished, you will rest for a little while. If you’re having both eyes done on the same day, the surgeon will probably do the other eye after a short period of time. Some people choose to have their second eye done a week later.

The doctor may prescribe medication for any postoperative pain, but many people feel no more than mild discomfort after LASIK, whereas painkillers are often prescribed after a PRK procedure.

After the procedure, you will be advised to take proper rest. What occurs after the surgery can affect your vision just as much as the operation itself.

You may be able to go to work the next day, but many doctors advise a couple of days of rest instead. They also recommend no strenuous exercise for up to a week afterwards, as this can traumatise the eye and affect healing. Avoid rubbing your eye as there is a chance of dislodging the corneal flap.

Laser eye surgery is costly and, at present, not normally available on the National Health Service in the UK or under most health-insurance schemes in the US.

A straw poll of clinics revealed variable prices - most charging upwards of £1200 per eye, or more in the small number of centres offering the more advanced wavefront technology (see box, p 3). In the US, the Los Angeles Times reports a typical price of between $1500 and $2000 per eye. Potential patients need to check whether the prices include aftercare, and any necessary repair or retreatment in case of disappointing results. Heather Welford, with additional reporting by Bryan Hubbard