Frequently Asked Questions about LASIK Eye Surgery.
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Dr David Kent

Who is suitable for laser eye surgery?

Not everyone is suitable to have HD LASIK i.e. if you are severely short-sighted -15.00 you may be recommended an implantable contact lens. Ideally the right criteria should be:
•    Between the age of 18 and 60 years old when your vision is most stable.
•    Without any pre-exisiting untreated eye conditions.
•    You should not be pregnant or breastfeeding.
•    Suitable for shortsighted, longsighted and astigmatism

Will it hurt?

Anaesthetic eye drops are placed into your eye prior to treatment to numb the eye so there is usually no pain experienced during the procedure. You will be aware of some pressure against your eye. For several hours after the procedure you may experience a grittiness or irritation. This irritation lasts about 4 or 5 hours. Some people do experience mild pain after LASIK surgery that can be relieved with pain relief tablets (Panadol).

Why I should choose to have LASIK at Fendalton Eye Clinic?

The care we take of you, the experience of the surgeon and the quality of the technology that we use.

  • Our staff care about giving you the best result for you as an individual.
  • Dr. Kent is one of the most experienced LASIK surgeons for laser vision correction in Australasia having performed more LASIK procedures than any other New Zealand eye surgeon. As with any operation the more experience the surgeon has the less likely a complication due to surgeon error is.
  • We are the only clinic in the South Island to offer you the greater safety, accuracy and superior results of HD LASIK using the Zeiss VisuMax® femtosecond laser.
  • We perform 100% personalised treatments so that every laser treatment is tailor-made to each individual eye.
  • The Schwind Amaris 1050RS excimer laser is the most advanced excimer laser on the market providing fastest treatment time and 7 dimensional eye tracking.
  • We do everything we can to give you the best result possible. Follow up after HD LASIK at Fendalton Eye Clinic is for six months. Within New Zealand the cost of follow up appointments is met by    Fendalton Eye Clinic. Enhancement is free of charge within twelve months of the initial HD LASIK treatment. We do not have a rigid criteria for enhancement correction. An enhancement will be done if it will  improve your visual result and can safely be performed.
  • A database is kept of all of Dr Kent's results. Dr Kent constantly analyses all of his laser treatment results at Fendalton Eye Clinic.
  • At Fendalton Eye Clinic we have a state-of-the-art purpose-built laser eye surgery theatre


Is there an upper age limit for HD LASIK?

Over the age of 60 years there is a high likelihood that you will have early or mild cataracts. The best surgical option for correction of distance focusing problems is to have cataract extraction and intraocular lens implantation.

In most cases we would use a multifocal intraocular lens to give the best chance of seeing clearly for both distance and near vision without spectacles.

Has Dr Kent performed laser eye surgery on other Doctors, optometrists or any of the staff at Fendalton Eye Clinic?

Since 1997 he has has performed laser eye surgery on more than two hundred medical doctors and optometrists combined. Dr Kent has performed laser vision correction procedures on five of his staff members and several of his relatives. Dr Kent has also treated many national sporting representatives.

What type of anaesthetic is used for laser eye surgery?

All laser eye surgery vision correction procedures are performed with anaesthetic drops placed in the eye which are extremely effective at completely numbing your eyes.
A mild sedative is also offered 30 minutes before your procedure, it does not put you to sleep but helps to relax you beforehand.

Could I have PRK rather than HD LASIK?

For some patients it is safer to have PRK than LASIK if the cornea is very thin. With PRK good results can be expected for low corrections. PRK has been shown to have no significant long-term complications. However even in very low corrections there is a longer time before clear vision is obtained after PRK.


How do the visual outcomes of Zeiss VisuMax® femtosecond initiated LASIK compare to traditional microkeratome initiated LASIK?

Clinical studies that have randomised patients to one eye with femtosecond LASIK and the fellow eye to microkeratome LASIK are the only scientifically valid way to compare the two techniques. These studies show that:

  • More patients achieve 20/20 or better vision with femtosecond-initiated LASIK.
  • Patients stating a preference preferred the post-operative vision of their IntraLase-treated eye 3-to-1 over their blade-treated eye.
  • Femtosecond laser creates fewer high- and low-order aberrations, associated with night glare and halos.
  • Femtosecond laser patients have a reduced incidence of post-operative dry eye symptoms.
  • Femtosecond lsaer patients required fewer enhancement procedures following LASIK.
  • The precision of the femtosecond laser flap significantly reduces the incidence of post-operative induced astigmatism as compared to a microkeratome-created flap.

What are some of the pros and cons of having Photorefractive Keratectomy (PRK)?

PRK is a good option for people who are not suitable for HD LASIK® due to having a thin cornea; a cornea that does not have a symmetrical shape; or anyone at high risk of eye injury.

Advantages of Photorefractive Keratectomy (PRK)

  • Leaves more corneal tissue untouched, making it safer if the cornea is thin.
  • Almost no long-term risk of developing keratectasia (bulging cornea).
  • Proven to have no visually significant complications after 10 years of follow up.
  • None of the possible flap-related complications of LASIK.
  • The structural strength of the cornea is not significantly altered.


Disadvantages of Photorefractive Keratectomy (PRK)

  • Can be painful for 2-3 days afterwards (although this is much less of a problem that it was in the past)
  • May take 7-10 days to achieve clear vision, requiring up to a week off work.
  • Some people develop a pronounced healing response in the cornea leading to deposition of new tissue. This causes corneal haze.
  • Not very predictable results in higher myopia or high astigmatism.

Why do some surgeons still use the steel bladed microkeratome?

The steel-bladed device of a microkeratome oscillates to cut the LASIK flap, rather than using a femtosecond laser. This 1990s technology costs about 1/7th to purchase the mechanical device and does not require the 24 hour climate controlled environment the femtosecond laser precision device requires - making the microkeratome much cheaper to run.

The added level of safety, precision and accuracy offered by HD LASIK® using the femtosecond laser and Schwind Amaris excimer laser is the preferred option for world-class surgeons, like Dr Kent. Surgeons who offer "all laser LASIK" are leaders in the field of ophthalmology, continually evaluating advances in eye technology. They have determined that femtosecond laser tecnhnolgy is the most sophisticated and accurate system available today and have invested in this level of technology to sustain their leadership in patient care.

How does the corneal flap affect visual outcomes?

Surgeons have found statistically and clinically significant differences in the vision patients achieve when a femtosecond laser is used for corneal flap creation. The Zeiss VisuMax® laser goes beyond simply creating a safer, planar flap to preparing an optimal corneal architecture below the flap, providing for superior visual outcomes. The end result: fewer complications and better vision.

What is femtosecond laser initiated LASIK?

Femtosecond-initiated LASIK (Laser In-Situ Keratomileusis) uses the Zeiss VisuMax® laser (a femtosecond laser) to complete the first step of the LASIK procedure. Femtosecond laser technology created a new era in LASIK laser eye surgery, by doing away with the mircokeratome blade and moving to an all-laser procedure. To deliver optimal results, all leading centres worldwide use a femtosecond laser rather than a bladed mircokeratome for the first step of the LASIK procedure, we term this all laser technique High Definition LASIK.

Noted for improving the safety and predictably of LASIK, the femtosecond laser replaces the oscillating microkeratome blade historically used in the first step. The femtosecond laser has also been proven to increase the chance of achieving normal 20/20 vision or better.

Today, femtosecond laser is the technology of choice among the world's leading LASIK surgeons and at ophthalmic teaching institutions. LASIK using a femtosecond laser has been approved by both NASA and for US Naval Aviators (Top Gun pilots). Microkeratome LASIK is not approved due to the higher risk of complications and reduced quality of vision in low-light situations.

When treating both eyes at the same time is the same equipment used for each eye?

No. We do not compromise on quality. With the IntraLase iFS a new disposable set up is used to treat each eye.

Laser eye clinics in New Zealand that only offer microkeratome LASIK, almost always use the same microkeratome, same steel blade and same surgical instruments for both eyes.

What is a femtosecond laser?

A femtosecond laser generates light pulses as short as one quadrillionth of a second. Femtosecond technology has opened up a whole new area of scientific study, femtochemistry, which won the 1999 Nobel Prize in Chemistry. The application of the femtosecond laser in ophthalmology was developed by physicists, biomedical engineers and ophthalmologists at the Center for Ultrafast Optical Sciences and the Kellogg Eye Center, University of Michigan, USA. The femtosecond laser has become the most accurate and safest technology for the corneal flap creation available today.

What is the success rate?

Our results show that 98% of people with moderate myopia can expect to achieve 20/20 vision or better after an initial treatment. About 2 % will require an enhancement
Globally millions of people have had LASIK to correct their vision and are happy with the result.

What are the different types of laser eye surgery advertised?

PRK: (also referred as ASLA) Photorefractive Keratectomy or Advanced Surface Laser Ablation
•    The use of one laser (excimer) without the creation of a corneal flap. The surface epithelium is exfoliated to allow the laser (excimer) to be applied to the corneal bed.
•    The epithelium then regenerates naturally.

LASIK: Laser In-situ Keratomileusis, in use since 1991.
•    A microkeratome (a bladed mechanical surgical cutting instrument) is used to form a thin flap on the front of the cornea.
•    The flap is lifted and the laser is applied to the exposed deeper corneal bed. The flap is then replaced and correctly repositioned over the modified corneal bed, conforming to the new shape.

HD LASIK (laser-initiated LASIK)
•    A Femotosecond laser is used to form a thin Flap on the front of the cornea.
•    The flap is lifted and the laser is applied to the exposed deeper corneal bed. The flap is then replaced and correctly repositioned over the modified corneal bed, conforming to the new shape.

•    The use of just a Femtosecond laser to create a “micro incision” rather than a flap. The laser also creates a lenticular shaped piece of tissue that is then removed with forceps via the “micro incision”.







Patient Selection


Myopia Correction

-0.50 to -6.00

-0.50 to -10.00

-0.50 to -10.00

Greater than -2.00


+0.50 to +4.00

+0.50 to +4.00

+0.50 to +4.00

Not possible

Astigmatism correction





Presbyopia correction





Wavefront Customised





Treatment options


Flap Creation

No Flap

Microkeratome flap (blade)

Zeiss VisuMax®  (laser)

No Flap (laser flocket)

Eye Tracking





Visual Recovery

Slow 4-6 days

Quick 24 hours

Quick 24 hours

Moderate to quick 1-2 days

Enhancement in case of residual power





Note: SMILE is a new technology unable to treat low myopia, hyperopia and astigmatism.  The accuracy of HD LASIK and PRK remain the standard choice for these correction.

What happens if I move my eye?

Active 7D eye tracking
The 7D active eye tracker impresses through a number of benefits: Apart from the linear movements (1st and 2nd dimensions) it compensates rolling movements of the eye (3rd and 4th dimensions). Compensation of the eye’s rotation around its optical axis is achieved with the static and dynamic Advanced Cyclotorsion Control (5th dimension). Movements along the z-axis (sixth dimension) are actively compensated by means of the z-tracking. Automatic pupil size control and pupil centroid shift compensation ensure additional safety.

Latency-Free Tracking in the 7th dimension
The new, ground-breaking Latency-Free Tracking considers the time factor, i.e. the 7th dimension. Latency-Free Tracking compensates for eye movements that occur in the period between acquisition of the eyetracker image and triggering of the subsequent laser pulses

Can I have both eyes done with HD LASIK at the same time?

Yes. It is safe to do both eyes one after the other, especially with the greater safety offered by eliminating the microkeratome blade by providing "all-laser" HD LASIK instead. Dr. Kent has offered same day both eye LASIK since September 1997, the first New Zealand eye surgeon to do so.


What are the risks?

With over 20,000 laser procedures done at FEC, we have not had anyone go blind. As far as we know no clinic in New Zealand has had anyone go blind following LASIK.
With all medical  procedures, there is a possibility of complications. However, complications that could threaten your vision are extremely rare these need to be discussed with your surgeon.

How long do I have to be out of my contact lenses prior to LASIK?

Contact lenses can affect the natural curvature of the cornea. You will be required to cease wearing contact lenses for a period of time leading up to your LASIK treatment. This period without contact lenses allows the cornea to return to its natural state, which will optimise the treatment outcome. The period without contact lenses depends on the type of contact lens that you are wearing.


  • Soft daily wear or disposable contact lenses should not be worn for 12 days before surgery.
  • Soft toric (astigmatism correcting) contact lenses. This type of contact lens "moulds" the cornea more than a standard soft contact lens. Therefore we advise you to cease wearing soft toric contact lenses for three weeks prior to your treatment.
  • Hard or rigid gas permeable (RGP) contact lenses. This type of lens maintains its own shape while on your eye. They therefore have a greater moulding effect on the cornea. You will need to cease wearing hard or RGP lenses for 6-8 weeks prior to your surgery.

If you do not have spectacles we may be able to supply you with a loaner pair that will be close to your prescription to assist you during the period that you are required to be out of contact lenses.

Can I go blind?

The risk of blindness from LASIK surgery is almost zero. Laser eye surgery is safer than wearing contact lenses.

An eye could become legally blind if there was a very bad eye infection after the surgery, which was unable to be controlled with antibiotic drugs. If such a serious complication did occur, then it would normally be possible to perform a corneal transplant and restore sight to that eye. This has never occurred in New Zealand.

What are the complications of HD LASIK?

Every procedure has the possibility of complications, with the majority of these resolving over time or being able to be managed with further treatment by Dr Kent:

  • Mild dry eye - Some people experience mild to moderate dry eye symptoms after laser eye treatment. Use of lubricating eyedrops may be required. By 3-6 months the eyes are usually back to normal. We have found that dry eye problems are less common with HD LASIK than with the older micokeratome bladed LASIK.
  • Undercorrection - If the refraction is not fully corrected and it causes a problem then an enhancement procedure can usually correct it.
  • Overcorrection - An initial overcorrection is expected for high corrections and in hyperopia.
  • Induced astigmatism - Can usually be corrected with enhancement procedure. Now very rare with IntraLase all-laser HD LASIK.
  • Regression – This is the normal healing of the eye and results in undercorrection. It is corrected with enhancement procedure.
  • Infection -We have had only one case in over 13,000 LASIK procedures which quickly responded to antibiotic eyedrops and resolved without complication.


When can I get back to work?

Normally we ask that you have a quiet day the day after the surgery. If you have HD LASIK, most people have their surgery on a Thursday, and are back at work on Monday. You should relax completely immediately after the surgery.

If you have PRK treatment the recovery time is longer. You are best to plan to be off work for seven days.

What is an 'enhancement'?

Enhancement surgery is additional treatment to "fine tune" the result. It takes one to three months from the initial surgery for the vision to be stable. During this time there may be some minor fluctuations in your vision. There is a lot of individual variation in the rate and amount that people heal. If after three months there is some under or over correction Dr Kent can offer you some additional lasering to optimise the outcome, providing it is safe to do so.

Enhancement surgery involves lifting the existing flap using fine surgical instruments to identify the edge of the flap and lift it to perform additional lasering. Generally enhancement surgery is more likely in higher or more complicated corrections. Enhancements are only needed in about 1% of cases of low short-sightedness. For higher corrections (over -8.0) there is a greater chance that an enhancement may be required. The overall rate of enhancement surgery following HD LASIK is about 4%. Enhancements are done free of charge within twelve months of the initial procedure as we want you to be happy with the final outcome.

Will laser eye surgery mean I will never need spectacles again?

In rare cases a full correction may not be achievable, if you have a high correction and a thin cornea. We will discuss this with you at your initial assessment. This may mean that you will need to wear spectacles occasionally eg driving at night time. Laser vision correction will not prevent your eyes from the normal ageing process.

There are some people who will have a change in their eyes with time. This can be either progression of myopia or hyperopia. There is no way of predicting if changes will occur with your eyes after your treatment prior to laser vision correction.

As with all people who have normal distance vision in both eyes you will require spectacles for reading at around age 45+. This aging of the eyes necessitating reading glasses at around 45+ in people with normal distance vision is called Presbyopia.

The only way to minimise your dependence for near vision spectacles once you become presbyopic is to have monovision. Monovision is where one eye is treated so that it is fully corrected for the distance while the other eye is focused for near vision. If you are considering monovision as an option we would give you some disposable contact lenses to simulate what the treatment would achieve and get you to trial this for a week or two to determine for yourself whether or not monovision will suit your lifestyle. We would be happy to discuss monovision with you further. Please contact us directly.

How can I keep my eye still and not blink during the surgery?

You do not have to worry about this. Your eye is held open by a lid speculum that makes it impossible for you to blink. There is a small bright green "fixation" light for you to look at during the procedure.
The total time of the lasering portion of your treatment is only 10-20 seconds, depending on your prescription.

How long has LASIK been done for?

LASIK using a microkeratome was first performed in Europe in 1991 and in New Zealand in 1995. IntraLase, femtosecond  "all laser LASIK" was first performed in the USA in 2001 and in New Zealand in 2006.

What about side effects such as transient light sensitivity and inflammation?

On rare occasions, some patients have reported transient light sensitivity (photophobia) at 2-6 weeks following IntraLase-initiated LASIK. This is due to an inflammatory response within the cornea. These side effects, while a nuisance, do not affect visual acuity and resolve with steroid eye drops. Almost all of these cases occurred with the older 15 and 30 kiloHeriz IntraLase models.

What is LASEK and Epi-LASIK?

Laser epithelial keratomileusis (LASEK) and Epi-LASIK are outdated techniques for surface eye treatments. We recommend the latest in photorefractive keratectomy (PRK) as an alternative to HD LASIK® because of a thin or unsymmetrical cornea.

LASEK involves using 20% ethanol on the central 8-9 mm of the cornea, then lifting the epithelial layer as a flap, doing the excimer laser treatment to the front of the cornea and repositioning the epithelial layer. 

Visual results, post-operative course, advantages and disadvantages are much the same as PRK. However, due to the lack of significant advantages over photorefractive keratectomy (PRK), most eye surgeons have stopped performing the LASEK technique. 


Epi-LASIK involves using a microkeratome with a steel blade to cleave off the epithelial cell layer beneath its basal layer.

The epithelium is lifted as a flap and the excimer laser treatment done to the front surface of the cornea. The epithelial flap is repositioned and a soft contact lens fitted.

The ideal behind the Epi-LASIK technique is to make visual recovery faster than photorefractive keratectomy (PRK) . However to date the visual results, post-operative course, advantages and disadvantages are much the same as PRK.


At Fendalton Eye Clinic we have chosen the latest photorefractive keratectomy (PRK)  technique for our patients providing our patients with the safest, most accurate and precise treatment in advanced surface eye surgery. 

Can the flap be dislodged?

During the first few weeks after the surgery you do need to be careful of your eyes, as a sharp object in your eye could possibly dislodge the flap. If the flap did get dislodged, then it can be repositioned.

After six weeks the flap is well healed. The chance of the flap being dislodged at this point is remote. It would take an event that would otherwise cause a severe injury to your eye to cause a problem with the flap after six weeks.

How does the flap stick down?

The flap adheres back to the eye without the need for stitches. It is held in place until it heals by the natural stickiness of the inner layers of the cornea in combination with the "suction" effect of the back layer of cells (endothelium) of the cornea. Within four hours the front layer of cells (epithelium) heal over. We ask you to wear clear eye-shields after the surgery and overnight so that your eyes are not accidentally rubbed or bumped in the initial healing period.

What does 'seven dimensions' mean in Fendalton Eye Clinic's eye tracking system?

Our excimer laser (the one that performs the actual correction during LASIK), the Schwind Amaris 1050RS, registers all movements with an eye tracking system that compensates every movement of the eye up to the seventh dimension.

An analogy to explain the advanced seven dimensional eye tracker is to imagine your eyeball being a buoy in the sea: When the sea is calm, the buoy shifts from the left to the right or forward and backward. In a swell, however, the buoy tilts to the side. Furthermore, a buoy also turns around its anchorage or moves up and down. In the same manner, your eyeball can make linear movements (1st and 2nd dimensions), rolling movements (3rd and 4th dimensions), rotate around its own axis (5th dimension) or move up and down along the z-axis (6th dimension). The 7th dimension considers the time factor and compensates for eye movements that occur during the reaction time of the laser system.

That means our laser treatment is delivered without latency.

When were intraocular lenses (IOL) invented?

The Intraocular Lens (IOL) was invented in 1949 by Sir Harold Ridley who pioneered IOL surgery for cataract patients.  Ridley pioneered this treatment in the face of prolonged strong opposition from the medical community. His process has been refined over time and is routinely used in modern cataract surgery.

What options are there for intraocular lens (IOL) surgery?

There are four main options for IOL surgery today.

IOL Option



Monofocal IOLs for emmetropia

Clear distance vision, no significant halos or glare

Total  presbyopia, glasses required for intermediate and near vision

Monofocal IOL monovision

Can see distance with one eye and near with the other.  Can be corrected for distance or near with spectacles.

Loss of binocular vision, adaptation to monovision may not happen in some, reading speed is slower than bilateral multifocal IOLs.

Extended-depth-focus IOLs (e.g. Oculentis Comfort)

Good distance and intermediate distance vision, some near vision.  Minimal optical side effects.

May notice a crescent shaped area of light below a light at night time.  Weak reading glasses usually needed.

Zeiss trifocal IOL

Good unaided distance, intermediate and near vision.

Halos around lights at night time.  Some patients experience mild glare.