How Does Laser Eye Surgery Work?

Laser Eye Surgery employs laser technology to reshape the cornea.

Any procedure that corrects the focusing power of the eye is known as refractive surgery. When this involves the use of lasers to reshape the cornea, this is known as laser refractive surgery or Laser Eye Surgery.

This set of procedures can be used to correct a full range of refractive errors, including myopia (short-sightedness), hyperopia (long-sightedness), astigmatism, and presbyopia. This is done by using ultraviolet light beams to remove tissue from the cornea – the transparent, curved window at the front of the eye.

These adjustments change the curvature of the cornea, allowing light to be focused more effectively on the retina at the back of the eye. Today, Laser Eye Surgery is the world’s most common elective surgical procedure.

During the treatment, the surgeon will gain access to the corneal tissue either by removing an area of the corneal epithelium or by creating a small hole in the cornea. Then, using a programmed laser to deliver pulses to the corneal, a small amount of tissue is removed.

Anaesthetic drops are applied directly yo the eye to prevent pain and discomfort during the procedure.

The different types of Laser Eye Surgery

LASIK (laser-assisted in-situ keratomileusis) is the most common form of Laser Eye Surgery.

This technique involves using a femtosecond laser (or in rare cases, a mechanical blade) to create a thin corneal flap, about a tenth of a millimetre thick.

A second laser – known as an excimer laser – is then used to sculpt the bed of the cornea. This can be to flatten the cornea (to correct short-sightedness), make the cornea steeper (to correct long-sightedness), or make it more symmetrical (to correct astigmatism).

Once the cornea has been reshaped, the corneal flap is simply put back in place.

ReLEx SMILE is a less invasive, “keyhole” form of Laser Eye Surgery.

SMILE (Small Incision Lenticule Extraction) is the least invasive method of Laser Eye Surgery. It does not require the creation of a flap, instead involving a tiny “keyhole” incision. A femtosecond laser is used to create this incision, delivering pulses from the laser.

These pulses create tiny bubbles (less than 1/100th of the width of a human hair) that create a connecting tunnel from the surface of the cornea to the corneal bed beneath.

The main advantage of SMILE over other Laser Eye Surgery techniques is its minimally invasive nature. This means that healing times are incredibly short and side effects are minimised. Furthermore, SMILE can be used to treat even higher prescriptions than was previously deemed possible and is often a preferred option for patients with drier eyes or thinner corneas.

In most patients, the flap (in LASIK) or the tunnel (in SMILE) heals within a matter of hours. While it is normal to experience some discomfort in the hours following treatment, this can usually be managed with painkillers and lubricating eye drops.

Most patients notice a significant vision improvement immediately after surgery, and vision continues to improve over the next 24-48 hours.

This rapid recovery time means that most patients can return to work within 24 hours of surgery, although it will take around three months for optimum visual outcomes to be realised.

A small number of patients are offered PRK/LASEK.

For the small minority of patients who are unsuitable for either LASIK or SMILE laser eye surgery, surface procedures may be offered. PRK (photorefractive keratectomy) and LASEK (laser sub-epithelial keratomileusis) are more invasive than SMILE and LASIK, but the outcomes are largely the same.

Surface procedures are so-called because they involve the complete removal of a portion of the epithelium (the surface layer). For the patient, the main difference between LASIK or SMILE and these surface procedures is the healing time. After a surface procedure, it takes approximately 5 – 7 days for the eyes to heal, and for vision to stabilise.