How Does the Normal Eye Work?
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?
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?
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 longsighted eye
What is Presbyopia
A compromise system called mono-vision may suit many patients, allowing both near and distance vision without glasses.
What is Monovision
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. Many patients do not feel comfortable with monovision and choose to have both eyes corrected for distance, and will use glasses for near tasks after age 45. However a large proportion of Dr Cherny’s patients choose to have monovision treatment, and find they can then do most tasks comfortably for both distance and near without glasses, even after age 45.
Who is Suitable for Excimer Laser Surgery
Dr Cherny’s general guidelines are:
- Patients should feel that they are not content with the options of glasses and contact lenses.
- Age minimum is 21 years.
- The glasses prescription should be stable for at least 12 months.
- Patients with myopia, hypermetropia (or hyperopia) or astigmatism can be considered for treatment.
- Patients must be prepared to pay the costs of treatment as there is usually no rebate from Medicare or health insurance.
- Patients must understand the nature of the treatment, the risks and benefits.
- Patients must agree to attend appropriate post operative follow up visits.
- Patients must have eyes that are otherwise healthy, and must have a cornea of suitable thickness.
- Patients must have a refractive error that Dr Cherny believes has a high likelihood of being successfully treated.
- Patients must have realistic goals and expectations of the treatment.
Is Excimer Laser Treatment Covered by Private Health Insurance?
Do I See Dr. Cherny Personally?
What are the Clinical Results?
The vast majority of Dr Cherny’s patients are happy with their short, medium and long term results.
Millions of patients have been treated with Excimer laser worldwide over the last 20 years. Follow-up studies continue.
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.
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
- Information Session with Dr Cherny (Free)
- “Check-up” session where eye drops are used and a full eye examination is performed by Dr Cherny (Free) This can be combined with the information session. This usually takes approximately 2 hours.
- The treatment. You will be at our centre for approximately 90 minutes.
- Follow up visits the next day then after 1 week, 1, 6 and 12 months (included in the cost of treatment if performed in Dr Cherny’s office)
Soft contact lenses need to be removed one week prior to the visit, 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 one day prior to surgery.
What to Expect on the Day of Treatment?
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 bed 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 and create a flap with the Intralase machine when Lasik is being performed.
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
The patient cannot drive, and must return home to rest for the entire day until the next morning. Most Lasik 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 require some additional checks during the first week after surgery.
PRK patients may experience some discomfort during 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.
Most patients are reviewed the day following surgery , then after 1 week, 6 months 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 20 years of international data and experience of follow up with PRK and 15 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:
Uncommonly, the eye may become overcorrected and be far-sighted rather than shortsighted.
Undercorrection means that the eye remains shortsighted after the eye has stabilised. Should the degree of residual myopia be of sufficient concern to the patients, the eye can usually be retreated at a later date.
This is a gradual returning of some of the refractive error.
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.
- Post Operative Pain
There is usually little or no pain with Lasik unless there is disruption to the surface cell of the cornea. PRK is more uncomfortable during the healing phase than Lasik.
The use of a contactblens as bandage , and pain killers help to reduce discomfort.
- 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.
- Corneal Haze and Scarring
This is usually only present in PRK patients. This occurs as part of the healing process after corneal remodelling 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.
- Halo Effect
This is an optical effect that is noticed usually 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.
- 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.
- 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.
- 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.
- 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.
Why does Dr Cherny wear glasses?
One of the questions that Dr Cherny is most frequently asked is “why haven’t you had laser to your eyes?” Simply explained, Dr Cherny is a happy glasses wearer, and enjoys the critically sharp vision that he requires for performing micro-surgery. He also has very dry and allergic eyes and this combination of factors make him an extremely poor candidate for this therapy. He is always happy to point out that if by wearing glasses himself he makes people ask “Gee, I need to think carefully about this, before having treatment”, then that is quite correct. Elective surgery on your eyes is a serious decision, and not everyone is suitable. Dr Cherny is more than happy to tell people if they are not suitable, and considers every patient who leaves his clinic well-informed but deciding not to have surgery a clinical success; they have addressed the issue and know exactly where they stand and are happy with his honest approach.
Many other eye surgeons, both in Australia and overseas, with different lifestyles and otherwise healthy eyes have chosen to have laser eye surgery for themselves, and for their children.