Refractive Eye Surgery

Refractive eye surgery covers any type of surgery on the eye where the objective is to improve the refractive state of the eye.

The most common reason for having refractive eye surgery is to decrease or even do away with a dependency on contact lenses or spectacles.

Today there are a number of methods for refractive eye surgery. The most common techniques involve the use of an excimer laser to re-shape the cornea so that light rays entering the eye are accurately refracted through the cornea and lens onto the correct part of the retina. Refractive eye surgery can be used to successfully treat shortsight (myopia), longsight (hyperopia), astigmatism and more recently age related longsight (presbyopia).

The two main categories of refractive eye surgery are;

- Excimer laser procedures
- Implant procedures

Excimer Laser Treatments

LASIK (Laser In Situ Keratomileusis) is the most common form of excimer surgery. There are two stages to the treatment; first a very thin flap is created on the surface of the cornea using a surgical device (microkeratome) or laser device. The flap is folded back to reveal the stroma. It is this tissue that is ‘lasered’ to correct the refractive error. The flap is folded back, acting like a tissue plaster and begins to heal immediately.

Eye drops are administered to help the healing process, although there is usually no pain, just a ‘gritty’ feeling in the eye for a short period of time.

Epi-LASIK is similar to LASIK, but is a treatment used on those patients with thin corneas. Rather than cut into the already thin cornea, an Epi-keratome is used to separate the very thin surface epithelium layer from the surface of the cornea (after applying alcohol) and this tissue is folded back prior to the laser treatment.
Following treatment it is maneuvered back into place to protect the treated area of the cornea. In addition a bandage contact lens is placed over the eye to assist with the healing process.

Epi-LASIK has been superseded by Trans-epithelial LASIK. Rather than damage the epithelium cells with alcohol, a laser is used to carefully remove this layer, leaving a very smooth corneal surface. This surface is treated once again with the laser and a bandage contact lens is placed over the eye to protect it and promote rapid healing. It has been found that the epithelium recovers and grows back much more quickly using this technique of laser refractive surgery.

Monovision

Monovision is a refractive eye surgery technique for those people who have got to the age when presbyopia (age related longsight) has set in. This change in the eyes focusing power is entirely natural and predictable. Most people use reading glasses to correct presbyopia to regain sharp ‘close up’ vision and take them off for other activities.

Whilst the fine focusing power of both eyes has been lost it is still possible to regain close up vision through Monovision - where one eye is adjusted to be dominant for close up work and the other eye remains dominant for distance vision.

This is achieved through refractive laser eye surgery. One eye is treated to see clearly at close up (dominant for shortsight) and the other eye is left as it is or adjusted with laser eye surgery to see clearly at distance (dominant for longsight).

It sometimes takes a little while for the brain to get used to the new information coming from the treated eyes but after six to eight weeks the adjustment is complete.

Contact lenses can be used to test to see if a patient will adapt to the adjusted vision before any refractive eye surgery takes place.

Refractive Surgery Implants

Intrastromal Corneal Ring Segments (INTACS)

The refractive error in your eye can be changed by the insertion of clear plastics implants into the cornea. These are called Intrastromal Corneal Ring Segments (INTACS) and are used to treat conditions like keratoconus.

A very small incision is made in the cornea and the INTACS are inserted and positioned either side of the pupil to effect the change in vision. They can also be removed at any time in the future.

Phakic Intraocular Lenses (Phakic IOLs)

Phakic IOLs have been developed for those patients suffering from high levels of myopia or hyperopia that is outside the safe treatment zone for laser eye surgery. The natural lens inside the eye is retained to maintain the close up focusing power of the eye. The Phakic IOL (also known as an implantable contact lens or ICL) is placed inside the eye infront of the natural lens, thereby changing the focusing power of the eye.