LASIK AND EXCIMER LASER EYESIGHT CORRECTION

INTRODUCTION  

Excimer laser eye surgery is the method of laser eye surgery which has revolutionised the treatment of shortsightedness and astigmatism since the early 1990’s. In 1983 scientists first used the Excimer Laser to engrave plastic, and an American ophthalmologist named Dr Steve Trokel later realised that the laser could be used to re-shape the cornea, thus overcoming the need for some patients to need glasses.

The name originally given to the correction of refractive errors with laser applications to the surface of the eye is Photorefractive Keratectomy (PRK) .

Since the mid 1990’s the same laser beam has been used to reshape the cornea after a flap of tissue is cut - this is called LASIK.

HOW DOES THE NORMAL EYE WORK?
In simple terms the eye is like a camera. Light hits the eye at the cornea. The cornea is the clear "windscreen" of the eye. As you look at an eye the cornea appears to be the "colored part", because the iris (which is colored) sits directly behind the cornea.

The cornea is in fact the major part of the eye that focuses light onto the retina. A structure called the lens sits inside the eye and completes the focusing of light, allowing a sharp image to appear on the retina. The retina turns the image into nerve signals which are passed by nerves to the brain.

WHAT IS SHORT-SIGHTEDNESS?  
Short-sightedness is also called MYOPIA. People who are short-sighted can see clearly at close range, but when looking across a room or down a street everything is out of focus.
The optical reason for myopia is that the light rays come to focus before they reach the retina.

Optics of a shortsighted eye

This is caused by the cornea being too curved, or the eyeball being too long. Often myopia runs in families. Myopia will often be first noticed in childhood and progress until the early twenties.

Short-sightedness is measured in dioptres, and is recorded on a prescription for glasses or contact lenses.
Low levels are 0-5 dioptres. High levels are 5-10 dioptres. Extreme levels are more than 10 dioptres.

WHAT IS ASTIGMATISM?  
Astigmatism exists when the cornea is slightly egg shaped instead of being regularly curved like a table-tennis ball. Objects appear blurred for both near and distance as the light rays entering the eye do not come to one single point of focus.

WHAT IS HYPERMETROPIA?  
Hypermetropia, otherwise known as long-sightedness, occurs in eyes that have a cornea that is too flat, or theoretically that the eye is too short. When a near or distant object is viewed, light enters the eye and comes to a point of focus somewhere behind the retina, rather than directly onto the retina. Hence near and distance vision is blurred.

Optics of a long-sighted eye

Long-sighted people have usually needed to wear glasses or contact lenses all the time since early in life.

What is MONOVISION ?

Rather than needing reading glasses after the age of approximately 45, a compromise system called monovision may be suitable for some patients, allowing both near and distance vision without glasses. One eye is treated to give sharp distance vision, and the other has a smaller treatment (or sometimes no treatment at all) and remains focused for near tasks.

Using both eyes together the brain mixes the signals from the two eyes, aiming to give comfortable near and distant vision. This arrangement can reduce or eliminate the need for reading glasses after the middle forties. It is a compromise arrangement, but one that can give the greatest number of years of freedom from glasses.

Dr Cherny likes to demonstrate this arrangement to his patients with lenses so that they can choose between monovision treatment, and full correction of both eyes. Approximately 20% of Dr Cherny’s patients choose to have monovision treatment.

PRESBYOPIA  
This is the normal need for reading glasses that develops in people who have "normal" eyes, and begins at around the age of 45. It is related to the normal aging process of the lens in the eye, where the natural focusing power of the lens is gradually diminished. People with refractive errors (short or long sighted) who have laser treatment and obtain normal distance vision, will still go through this normal aging process. Therefore reading glasses will still be needed at around the age of 45, even after laser treatment.

A compromise system called mono-vision may be suitable for some patients, allowing both near and distance vision without glasses. Many patients do not feel comfortable with monovision Discuss this option with your Ophthalmologist.

GLASSES AND THEIR ALTERNATIVES  
For hundreds of years glasses have enabled people to see clearly. In recent decades contact lenses have been used successfully by millions of people. Many people are happy with these two methods of managing their visual needs, and don’t need to consider surgery to their eyes.
Others however find strong glasses produce distortion, or they may feel uncomfortable in glasses. Other patients find contact lenses troublesome or intolerable due to sensitivities or allergies.

It is these groups of patients who consider that surgical treatment of their refractive errors may be desirable.

In the 1970’s and 1980’s radial keratotomy (“the Russian Operation") received some public attention. It worked by cutting spoke like incisions into the edge of the cornea in order to flatten it centrally.

In Australia this type of surgery was not practiced by many surgeons. Inter-nationally many surgeons who were previously practicing radial keratotomy are now advising their patients that more predictable and stable results can be achieved with Excimer Laser.

Cataract surgery can also eliminate short-sightedness by replacing the eye’s natural lens with a weaker implant lens. This procedure is usually reserved for patients with cataracts, as there are small risks of retinal detachments and infection following surgery within the eyeball.

Other refractive surgical procedures that are developing, and practiced in much fewer numbers than Excimer Laser include phacic implant lenses, and intrastromal corneal rings.

HOW DOES THE EXCIMER LASER WORK?  
Excimer laser works by sending brief pulses of ultraviolet light onto the cornea. The light’s energy breaks apart molecules on the very surface of the cornea. Each pulse removes one quarter of one micron of tissue (it would take four thousand pulses of laser to pass through one millimetre of tissue). The laser gradually sculpts the cornea to the desired shape.

"this microscopic picture
of a human hair with ridges
cut into it with a Excimer laser
demonstrates the precision
of the laser in removing
minute amounts of tissue"

The removal of 10 microns of corneal tissue corrects one dioptre of myopia. This is an extremely small change to the corneal thickness. (As a comparison, a human hair is 50 to 100 microns thick).

WHAT IS LASIK ?  

LASIK is a modification of Excimer refractive surgery. The same laser machine is used. Prior to applying the laser a thin flap of the cornea is created using a special automated surgical tool. The flap is very thin (0.16 mm). The flap is still attached to the eye at its edge, so that it can be folded back into position after the laser has been applied. Overnight the flap secures itself by healing across the surface cells at the edge of the flap. Patients can return to most normal activities the next day and the procedure has very little discomfort for almost all patients.

                                    The precision made micro-                                           After the corneal flap is formed
                                      keratome creates the flap                                        the laser is delivered to the cornea

How is the LASIK flap made? 

A precision manufactured semi automatic microsurgical tool called a micro keratome is used to create the LASIK flap.

WHAT ARE THE ADVANTAGES OF LASIK COMPARED TO PRK LASER TREATMENT?  
The short-term advantage for the patient is that the eye is much less painful after LASIK than after standard surface laser (PRK), and the visual recovery is faster.
The long term advantages of LASIK include reduced risk of scarring and increased stability of the vision for higher levels of myopia. Stable vision returns faster after LASIK, and eye drops are usually only needed for one week.

WHAT ARE THE DISADVANTAGES OF LASIK COMPARED TO PRK LASER TREATMENT?
The long-term disadvantages of LASIK include increased potential complications either because the flap may be incorrectly formed, or material (dust, germs, and cells) can theoretically become trapped under the flap.
The vast majority of excimer laser patients are now treated with Lasik rather than PRK.

Dr Cherny can discuss with each patient the relative advantages and disadvantages of LASIK in their individual situation.

WHEN IS EXCIMER LASER SURGERY CONSIDERED?  
Excimer Laser Surgery (either PRK or LASIK) can be considered in the following circumstances:
1.For those patients with short-sightedness or astigmatism who desire to be more independent of their glasses and contact lenses.
2.For those patients who cannot use glasses or contacts because of their occupation, or due to their recreational interests (e.g. swimming, yachting, scuba diving, skiing etc).
3.For those patients who find thick spectacle lenses to be visually or socially restrictive.

Dr Cherny will be able to answer any questions you may have regarding the advantages and disadvantages of glasses, contact lenses and Radial Keratotomy compared to Excimer laser surgery.

WHO IS SUITABLE FOR EXCIMER LASER SURGERY?  
Dr Cherny’s general guidelines are:
1. Patients should feel that they are not content with the options of glasses and contact lenses.
2. Age minimum is 21 years.
3. The glasses prescription should be stable for at least 12 months.
4. Patients with myopia, hypermetropia (or hyperopia) or astigmatism can be considered for treatment.
5. Patients must be prepared to pay the costs of treatment as there is no rebate from Medicare.
6. Patients must understand the nature of the treatment, the risks and benefits.
7. Patients must agree to attend appropriate post operative follow up visits.
8. Patients must have eyes that are otherwise healthy, and must have a cornea of suitable thickness.
9. Patients must have a refractive error that Dr Cherny believes has a high likelihood of being successfully treated.
10. Patients must have realistic goals and expectations of the treatment.

IS EXCIMER LASER TREATMENT COVERED BY PRIVATE HEALTH INSURAMCE ?  
Usually not, but some private health insurance companies now offer a rebate of up to $500 per eye. Patients should check with their insurance company to find out if a rebate exists.

Many patients may receive a taxation rebate. A taxation rebate of approximately $300 usually applies for patients having both eyes treated in one financial year.

DO I SEE DR.CHERNY PERSONALY ?

Yes, each patient’s specific details will be discussed in depth with Dr. Cherny to assess their suitability for laser surgery, and patients are given multiple opportunities to ask Dr Cherny any questions they may have.

WHAT ARE THE CLINICAL RESULTS ?

Millions of patients have been treated with Excimer laser worldwide. Follow-up studies are being carried out to assess whether any long-term complications develop. To date severe long term complications have been rare. If too much corneal tissue is removed progressive thinning and distortion of the cornea can occur. Measuring the corneal thickness before treatment and calculating the amount of cornea that will be left behind reduces the risk of this complication.

Analysis of the results of patients treated by Dr Cherny show that:

For patients with less than 6 dioptres of myopia on the cornea, 97% of eyes treated can see 6/12 or better without glasses 3 months after surgery
- 6/12 is a measurement of vision from an eye chart and is the standard level required to legally drive a car in Victoria; 83% of eyes achieve 6/6 or better

For patients with myopia between 6 and 10 dioptres on the cornea, 83% can see 6/12 or better without glasses at 3 months; 54% of eyes achieve 6/6 or better

Almost all patients find that they are much less dependent on glasses. Most patients find they no longer need to use glasses or contact lenses other than non-prescription sunglasses, unless they are over age 45 who require reading glasses.

Very few patients still need to wear glasses or contact lenses regularly to achieve vision good enough for comfortable driving and television viewing.
It is rare for a patient to feel that their vision has been made worse as a result of the treatment.

It must be emphasised that most people will need to wear reading glasses for fine, near work when they get older, unless they have chosen a monovision treatment.

WHAT ARE THE STEPS I MUST TAKE TO HAVE THE PROCEDURE PERFORMED BY DR.CHERNY ?

1. Information Session with Dr Cherny (Free)
2. Work up session where eye drops are used and a full eye examination is performed by Dr Cherny (Free)
3. Corneal mapping tests (Free)
4. The operation
5. Follow up visits the next day then after 1 week, 1, 3, 6 and 12 months (included in the cost of treatment if performed in Dr Cherny’s office)

INFORMATION SESSION

Dr Cherny holds regular free information sessions on Laser Eyesight Correction. This is held in a small group format. The sessions last about one hour, and patients have the opportunity to ask him questions about the treatment options. The information session provides a basic explanation of Excimer Laser surgery, its benefits, alternatives and complications. There is no obligation to make any commitment to surgery.

"WORK UP" SESSIONS

Patients who have attended an information session and wish to undergo surgery next attend for a private consultation and examination session. Eye drops are used to open the pupil, and the patient can not drive for 2 hours after this assessment.

Soft lenses must be left off the eye a minimum of 1 week, and rigid gas permeable lenses must be left out for four weeks. After the work up examination contact lens wear can be recommenced. All contact lenses must be discontinued in the 24 hours before surgery.

PRE-OPERATIVE CORNEAL MAPS AND CORNEAL THICKNESS

All patients must have these tests performed prior to surgery at the laser centre.
If the cornea is too thin or irregular in shape, surgery may not be possible.

CONSENT FORM

An informed consent form must be signed before the laser treatment is performed.

WHAT TO EXPECT ON THE DAY OF TREATMENT ?
> The operation is a walk-in, walk-out procedure
> A friend or relative who can provide transport after the procedure should accompany the patient
> Patients spend approximately 90 minutes in the building, but only twenty minutes in the treatment room
> Anaesthetic eye drops numb the eye
> The patient is positioned on a motorised reclining chair with the eye to be treated under the operating microscope

> The other eye is covered during the procedure.
> A clamp holds the eye lids gently open
> Before the actual treatment the patient is familiarised with the way in which the laser will work
> When all is ready Dr Cherny performs the treatment using the laser to reshape the cornea
> The patient can see a flashing light in the microscope, and must look straight at the flashing light..
> The actual laser delivery lasts only 20 to 60 seconds, during which time the patient must look at the fixation light
> There is no pain from the laser
> Most patients find the treatment is not uncomfortable, and cope easily with the procedure.

AFTER EXCIMER LASER SURGERY  
After treatment a clear plastic cover is put over the eye.

The patient cannot drive, and must return home to rest for the entire day until the next morning. Most patients can drive to the check up the next morning then go to work. Often there will be some red bruising on the white of the eye that settles over 10 days.

PRK patients are reviewed after 48 hours, then after 1 week, 1, 3, 6 and 12 months. PRK patients may experience pain for the first 24-72 hours after treatment due to the removal of the surface layer of the cornea.

If Lasik is performed there is usually no pain, only a mild irritation.
Post-operative medication, such as analgesics, will be supplied to help ease any discomfort.
Lasik patients are reviewed the next morning, and at 1 week, 1, 3, 6 and 12 months after surgery.

WHAT ARE THE POSSIBLE SIDE-EFFECTS AND COMPLICATIONS OF EXCIMER LASER SURGERY ?
Many leading eye surgeons around the world are delighted with the results of this treatment, and are optimistic that it is safe in the long term. However, as with any surgery, complications are possible. Whilst there is over 10 years follow up with PRK and 7 years follow up with LASIK , it is impossible to rule out long term complications that may not yet be recognised.

The following possible side effects and complications should be considered:

1. Overcorrection
Uncommonly, the eye may become overcorrected and be far-sighted rather than shortsighted.

2. Undercorrection
Undercorrection means that the eye remains shortsighted after the eye has stabilised. This may be planned for or occur as an unintentional effect. Should the degree of residual myopia be of sufficient concern to the patients, the eye can usually be retreated at a later date.

3. Regression
This is a gradual returning of some of the refractive error.

4. Decentration
Decentration of the zone of treatment is rare. Measures are undertaken to reduce the likelihood of this occurring.
Decentred treatments may cause permanent loss of sharpness and this may be difficult or impossible to reverse with current technology. If severe, contact lens wear may be needed to improve vision.

5. Post Operative Pain
There is usually little or no pain with Lasik unless there is disruption to the surface cell of the cornea. In PRK pain is frequent, hence the need for pain killers after PRK.

6. Delayed Epithelial Healing
If PRK is performed the surface epithelium is removed just prior to the laser surgery. It usually heals in 2 to 4 days but rarely there may be a delay in this process.

7. Corneal Haze and Scarring
This is usually only present in PRK patients. This occurs as part of the healing process after corneal remodeling and is usually at its maximum severity 6 weeks after the laser treatment. This gradually settles by 3 to 6 months. Steroid drops may be used to control the degree of haze. The haze is seen by the ophthalmologist with a microscope but is usually not detectable by the patient. If severe, it can permanently reduce the sharpness of vision.
In Lasik a faint scar at the edge of the flap away from the line of vision is can be seen after surgery when the eye is examined under the microscope. Central scarring is very rare after Lasik.

8. Halo Effect
This is an optical effect that is noticed in dim light as the pupil enlarges; as the pupil dilates the untreated peripheral cornea produces a second faded image. It is less frequent with larger treatment zones being used today and is less noticeable when the second eye is treated.

9. Light Sensitivity or Glare
This is not usually a significant problem however sunglasses are recommended. During the first few months there may rarely be some discomfort driving at night or in bright sunlight.

10. Dry eyes
A small proportion of patients experience a gritty feeling in the eyes after surgery. This can usually be controlled with lubricating drops, and usually settles over a period of weeks to months.

11. Flap complications
If the flap is not cut correctly, becomes folded or displaced the visual result can be imperfect. Germs, cells or other material can occasionally cause problems under the flap. Serious flap related problems are rare, and can usually be dealt with if they arise to improve and stabilise the situation. Unfortunately in very rare instances, flap complications can result in permanent reduction in vision, glare problems or ocular discomfort.

12. Other Complications
There are some additional complications which may be serious, for example, corneal infection, persistent corneal swelling, corneal perforation and cataract. Fortunately these are extremely rare.

COSTS 
Our fee for treatment is currently $1600 per eye, as at 1st July 2002.
The fee includes all examinations by Dr Cherny before treatment and after treatment for 12 months.

TIMES

Information sessions are held weekly, call for times on 1800 069 069.
Work up sessions and follow up appointments are by arrangement with our staff.
Treatments are usually Monday mornings or Friday afternoons.