Excimer Laser Vision Correction

Introduction

The Excimer Laser is used to correct refractive errors for distance vision, namely myopia, (short-sightedness), hyperopia (longsightedness) and astigmatism either on it`s own or in combination with myopia or hyperopia.

Patients who require reading glasses for near vision and for whom no glasses or contact lenses are required for distance vision, are not candidates for laser surgery.

The decision to proceed with Excimer Laser refractive surgery is a personal one, provided the ophthalmic examination is appropriately normal.

Myopia

This is the most common refractive problem affecting one in every four South Africans. Myopia is caused by an eyeball which is too long or a corneal curvature which is too steep. This in turn causes light rays to focus in front of the retina resulting in blurred distance vision.

Hyperopia

In Hyperopia the light rays are focused behind the retina, due to an eyeball which is too short or the corneal curvature which is too flat. This results in blurred distance vision, which worsens close up.

Astigmatism

Corneal Astigmatism causes a single focal point to separate into two focal points that are both out of focus with respect to the retina. The corneal surface distortion is similar to the shape of a rugby ball. Astigmatism can occur in isolation or in association with myopia or hyperopia.

Excimer Laser Procedure

Excimer Laser is the most advanced technology available for the correction of "distance" refractive errors. The laser is able to gently and precisely reshape the cornea to eliminate refractive errors. It is a painless procedure requiring only local anaesthetic eye drops.

The laser removes 0.25 microns of tissue per pulse and is unique in its ability to remove thin layers of the cornea without affecting the underlying layers. The corneal tissue undergoing treatment is vapourised during the Laser induced photo-disruption of molecular bonds. There is no heat nor explosive shock waves produced. Excimer Laser procedure is performed as an outpatient procedure in a surgically clean operating theatre and takes approximately 10 minutes per eye. During the procedure the eyelids are kept open by means of an eyelid speculum preventing involuntary blinking.

The Excimer Laser treatment reshapes the corneal curvature. In Myopia the corneal curvature is flattened, in astigmatism a symmetrical curvature is achieved and in Hyperopia the curvature is steepened. The procedure results in light rays focusing precisely on the retina.

The two Excimer Laser procedures used are Photorefractive Keratectomy (PRK) and Laser-assisted- in-Situ-Keratomileusis (LASIK).

PRK

The laser beam is directly applied to the surface of the cornea after the epithelium (outerskin) has been mechanically removed. The cornea requires a contact lens for a few days whilst re-epithelization takes place. The eye can be uncomfortable and painful during this healing period.

LASIK

A Thin flap of cornea is cut and then lifted aside out of the path of the ensuing laser beams. The treatment is then performed on the exposed corneal bed. After the treatment is completed the flap is replaced in its original position. Corneal factors account for a strong adhesion of the flap to its bed and no sutures are required.

The corneal surface is intact which results in a painless nearly immediate visual rehabilitation, without any risk of scarring. The Lasik technique is considered the most advanced technique.

Many of our patients have occupational needs for improved visual acuity (police, fire fighters, sportsmen and women to name a few). Others simply have a desire to be independent of glasses or contact lenses.

To wake up and see independently of glasses not only improves cosmesis but adds to one`s self-confidence.

LASIK Surgical Technique - External View - stage1

The microkeratome is used to produce a lamellar corneal flap. This external oblique view of the eye shows the lamellar corneal flap (F) being reflected (arrow) to expose the superficial corneal stroma.

LASIK Surgical Technique - External View - stage2

Once the corneal flap (F) is reflected, the stromal bed of the cornea (S) is ablated to a predetermined amount using the excimer laser(L).

LASIK Surgical Technique - External View - stage3

After the treatment is completed the corneal flap (F) is replaced in its original position. Dr Cilliers was were among the first refractive surgeons to perform Excimer Laser surgery in South Africa.

Who qualifies for surgery?

• Age 18 or older provided there has been stable corrected
  vision within the past 2 years.
• No corneal nor retinal diseases
• Realistic expectations
• A full understanding of side effects
• A full understanding of risks ( serious vision threatening complications can occur in less than 0.01 percent of patients )

What can I expect following excimer laser procedure?

The vast majority of patients (96%) achieve at least "driver`s licence" vision (20/40) or better within 12 hours of Laser surgery. In the case of approximately 4% of patients, an additional laser procedure (enhancement) is required to achieve the original target of independence. This enhancement is performed at no extra cost within the first year of surgery.

Remember that eyes can heal differently and consequently small refractive differences between the eyes occur which usually do not require optical correction. (This difference can occur in normal sighted individuals).

During the fourth decade a persons near-vision deteriorates naturally and independently of the laser treatment (presbyopia) and reading glasses will be required.

Answers to Frequently Asked Questions

Is there pain during and after the procedure?

Slight discomfort is experienced during the procedure. The majority of patients suffer a small measure of irritation and watering of the eyes for a few hours after the treatment. A measure of light sensitivity may be experienced for a few days.

How long does the procedure take?

About 10 to 15 minutes per eye.

How soon can I resume normal activity?

Functional vision returns within 12 hours. Patients in the "reading glass" age will require temporary readers. Resumption of sporting activities should be discussed with your ophthalmic surgeon. Swimming is normally allowed after two weeks following surgery.

Is the laser safe?

When performed by an experienced Excimer Laser surgeon, the risks are very low.

Is the procedure permanent?

Providing there is a stable refraction prior to the procedure, the answer is "yes". The results cannot be guaranteed in extreme old age due to the degeneration of eye tissue.

How will my vision after laser surgery compare with my vision with contact lenses or glasses?

Most patients maintain the sharpness of their vision after laser treatment. Approximately 1% loses one line of vision (slight loss of contrast). This is more common in patients with extreme refractive errors.

Will I experience side effects?

During the day some photophobia can be expected. Sunglasses cure this problem. At night glare and haloes can be expected immediately after the surgery. In most cases, these side-effects disappear within six months. Some patients may still require spectacles to improve night vision.

Can I still use contact lenses or glasses after the procedure?

Yes.

What follow-ups can I expect?

You will be examined on day one post-operatively and again within the first two to three weeks. Thereafter at intervals of three to six and twelve months.

What are the long term effects?

The laser has been performed successfully since ± 1984 and is currently FDA approved. No long term adverse effects are expected outside normal ageing or concurrent eye disease. If the integrity of the eye remains intact, stability appears to be excellent.