Advances in LASIK

Wavefront-guided customized LASIK Treatment

In customized LASIK treatment, the laser ablation is specifically designed to treat every individual eye and patient. A wavefront device is used to create a "power map" of the entire cornea, allowing the surgeon to treat small, localized areas. This allows accurate focusing of all light rays onto the fovea (centre of the retina)

Step 1

Step 1 of Wavefront-Guided Customised LASIK where a detailled aberrometer projects a laserbeam into the eye

Aberrometer projects the laserbeam into the eye and onto the fovea.

Step 2

Step 2 of Wavefront-Guided Customised LASIK where the laser light is reflected from the eye

Reflected laser light emerging from the eye.

Step 3

Step 3 of Wavefront-Guided Customised LASIK where a detailed power map is captured by the wavelight machine

Wavefront-customized LASIK treatment is beneficial to patients with distorted, irregular corneas and patients with large pupils. The procedure is most accurate for mild to moderate myopia (100 to 700 degrees).

Customised LASIK takes longer to complete than standard LASIK due to its expanded treatment zones and improved post-treatment profiles. In Wavefront guided customized treatments more visual distortions will be eliminated.

Wavefront optimised LASIK

After many years of performing standard LASIK, it was discovered that we were creating aberrations (visual distortions). Standard LASIK most commonly causes a visual distortion called spherical aberration. Spherical aberration causes halos and decreased night vision.

Wavefront optimised LASIK has been designed to address this surgically induced visual distortion - spherical aberration. When we use the laser to alter the cornea shape, we induce some contour distortions in the corneal periphery. Predicting these changes and compensating for these changes leads to a better final corneal shape (profile) and improved night vision, especially in the prevention of halos and glare.

This is a great advancement towards addressing a major post operative visual problem associated with standard LASIK, i.e. poor night vision.


A prolate cornea is a cornea that focuses all rays of light whether in the centre or the periphery, exactly on the macula which is the center of the retina.

After LASIK surgery, many patients are left with an oblate cornea. This causes loss of correct focus in the periphery of the cornea.

This causes halos and glare. Many lasers are creating oblate corneas just by the nature of their ablation/treatment patterns. Newer lasers, like the Allegretto Eye Q laser have the ability to create a prolate cornea. This betters night vision and many patients are reporting an improvement over their previous vision at night with glasses or contact lenses. This type of LASIK treatment has been called Custom-Q LASIK. The flattening of the cornea is more gentle and over a larger extent of the cornea's periphery. There is no sudden change in corneal contour. This shape change in treatment pattern has taken years of research and development as each eye is different and requires a highly customized approach.

At present, the shape of a person's cornea is measured and the amount of "prolateness" or Q value is calculated. The treatment pattern is designed to maintain or improve the patient's natural "prolateness".

All predators like eagles and humans have a prolate cornea. Animals preyed upon, like frogs, have oblate corneas. Eagles require sharp distance vision to catch prey while frogs need wide (but blurred) peripheral vision to make sure they are not caught by predators. Frogs do not need good distance vision as their food is usually within a few centimeters of their reach. Personally, I rather be an eagle than a frog!

PerfectShape™ LASIK

PerfectShape™ LASIK or Corneal Wavefront Q-Adjusted LASIK - Reduces Risk of Poor Night Vision

Wavefront guided, wavefront optimized, Zyoptix, Aspheric LASIK? Confused? These are all different ways to treat the cornea to correct shortsightedness and astigmatism.

Corneal Wavefront Q-Adjusted LASIK is the latest software development that Dr. Jerry Tan has developed since 2005. Pioneering this technique Dr. Tan has just presented results of this surgery at the ESCRS (European Society of Cataract and refractive Surgeons) in London England (9th -13th September 2006). He has also presented this treatment technique at the Wavelight Laser user's meeting in Vienna, Austria in June 2006. This treatment program marries the best aspects of all previous treatment programs into a single entity and improves on all previous treatment profiles. This results in a "PerfectShape™ Cornea" after this type of LASIK surgery. Jerry Tan Eye Surgery is the only centre in Asia providing this treatment. Doctors from Australia, Hong Kong, Korea, Taiwan and India are coming to learn this new treatment modality.

Night Vision Problems
The Achilles heel of standard and other LASIK and Epi-LASIK procedures is that they expose patients to a higher risk of poor night vision. This means patients' night vision may be distorted by glare and halos. It is now possible to reduce this risk with "PerfectShape™LASIK".

Results of a Night Vision survey done on 78 participants, 3 months after their "PerfectShape™ LASIK" surgery.

night vision rating after PerfectShape LASIK

Statistics of Difficulties of driving at night after PerfectShape LASIK

Picture of Normal Cornea Shape with Aberrations
Cornea with all the inherent imperfections found in all patients' pre-LASIK surgery

Picture of Cornea Shape after wavefront-guided LASIK Surgery

Cornea treated with Wavefront guided treatment - does not take into consideration original shape/contour of the cornea. It does not anticipate induced aberrations caused by the LASIK procedure.

Picture of Cornea Shape after Aspheric or Q-adjusted treatment

The Aspheric or Q-adjusted treatment is a very basic customization. It does not take into consideration the aberrations like coma and trefoil. This leaves behind imperfections that will deteriorate night vision in most patients. It treats only one of the three major aberrations.

picture of shape of cornea after PerfectShape LASIK
The inherent imperfections are smoothed over and the cornea reshaped into a "perfect" shape. It takes the original corneal contours, wavefront into consideration and anticipates the induced aberrations caused by the LASIK procedure. It treats all aberrations as well as reduces aberrations.

This is PerfectShape™ LASIK.

iFS™ IntraLase® LASIK

Jerry Tan Eye Surgery is pleased to offer to our patients the new 5th generation 150 kHz iFS™ IntraLase® Laser, providing an enhanced standard of precision and safety in the flap-making process in LASIK surgery.

We have been able to offer the IntraLase® method to create the flap since 2004. Starting with the 2nd generation laser then, and now using the 5th generation 150 kHz iFS™ IntraLase® Laser in 2009, we are now able to offer even better safety, precision and predictability with a faster speed (view video below).

Traditionally, doctors have used an instrument called a microkeratome for the creation of corneal flaps. The microkeratome is a hand-held blade that moves across the eye, cutting the corneal flap as it goes. While LASIK is extremely safe, if complications do occur the microkeratome is most often the cause.

One of the latest developments in LASIK is the development of a Femtosecond laser. At present, IntraLase® is the most established company producing a Femtosecond laser that is FDA approved, to create the LASIK flap. Since the year 2000, over 2 million IntraLase® procedures have been performed worldwide.

IntraLase® does not cut the flap; It is a 100% blade-free approach to creating your corneal flap. Tiny pulses of laser light, a quadrillionth of a second each, pass harmlessly through the outer portion of your cornea and form a uniform layer of microscopic bubbles just beneath the surface of your eye to split it into a superficial layer (the flap) and deep layer (the bed). It merges thousands of these bubbles into a contiguous layer to create the flap.

The exact dimensions of this layer of bubbles are determined by Dr Tan based on what's best for your eye, and are computer controlled for maximum precision - things that are not possible with a hand-held blade. The IntraLase® flap creation process takes about 20 to 25 seconds with the 4th generation 60 kHz laser, but currently with the 5th generation 150 kHz iFS™ IntraLase® Laser, the speed is 2.5 times faster, and the flap creation time has been reduced to only about 10 to 15 seconds.

Why IntraLase®?

  • Safety
    IntraLase® has the edge in safety.
    Buttonholes and partial flaps can occur with a microkeratome more frequently than with the Intralase. Microkeratome buttonholes occur 1 in 2000 cases.
  • Flap stability
    Flaps created using IntraLase® are also less likely to displace post-operatively.
  • Flap Configuration
    The depth, size and contour of the flap is more even, accurate and predictable with the Intralase. This is especially so for very flat or very curved corneas.
  • Aberrations
    Microkeratome flaps create slightly more optical aberrations/distortions than the IntraLase® flap. The IntraLase® Method delivers outstanding visual results: more patients achieve vision that is 20/20 or better when the IntraLase® Method is used. Patients also report better quality of vision overall, particularly in terms of their ability to see well in low light, such as at dusk or at night.
  • Better Comfort for Very Small Eyes
    The IntraLase® suction ring is soft and more comfortable in the small eye.
  • Less Dry Eye
    Patients who have undergone IntraLase® have reported less dry eye, a common temporary side effect of LASIK.

Disadvantages of Intralase

  • Inflammation
    Inflammation can occur more frequently with the Intralase, especially if the laser power is set at an incorrect and excessive power. Though this is easily controlled by topical eyedrops. this inflammation is minimal with the 5th generation iFS™ laser.
  • Expense
    IntraLase® is a much more expensive machine to purchase and maintain.
  • Though most patients opt for IntraLase® to enjoy the benefits, the eye evaluation will ascertain whether you are suitable candidate for Intralase.


Patients can now optimise their LASIK result with NeuroLASIK™!

NeuroLASIK™ is about the science of seeing better and takes care of your vision beyond your eyes!

We treat the entire visual system and maximize your visual potential by minimising the optical defects of the eye as well as enhancing the ability of your brain to effectively process visual information. This results in giving you the higher chance of achieving your best vision after LASIK at Jerry Tan Eye Surgery.

NeuroLASIK™ is a combination of Advanced Customised LASIK and NeuroVision™ therapy.

It will give you the best chance to see better than 20/20 or 6/6 vision after LASIK. A study conducted by Durrie et al showed the percentage of Post-LASIK patients with uncorrected VA of better than 20/20 increased from 75% to 96% after they completed NeuroVision™ program commencing 1 month after LASIK.

Schwind Amaris® 750S

When you decide on an eye laser treatment, you expect the best possible results. The SCHWIND AMARIS 750S offers you the leading technology for your laser treatment - superior in all important aspects: Speed, precision, safety and comfort.

Minimum treatment time
The SCHWIND AMARIS 750S works two to three times faster than other laser systems. 750 tiny light flashes per second shape the corneal surface. It is extremely fast and corrects one dioptre of myopia within 1.5 seconds, and eight dioptres are ablated within 13 seconds.

Automatic Fluence Level Adjustment

picture representation of Automatic Fluence Level Adjustment for the SCHWIND Amarais 750S Laser LASIK eye technology

In order to perfectly combine speed and precision, the SCHWIND AMARIS 750S is equipped - besides a 750 Hz pulse frequency - with two energy levels. At first, the SCHWIND AMARIS 750S uses a high energy level and rapidly ablates around 80 percent of the tissue to be removed - like a fast yacht quickly heading for the safe harbour. How long the powerful beams are applied depends on your individual refractive error and is continuously checked by the software during the treatment. Like a small sport boat then exactly navigates to a narrow landing, a gentler beam ablates the remaining 20 percent, thus assuring an especially smooth surface and perfect vision.

Eye tracking in six dimensions

picture representation of eye tracking in six dimensions for the SCHWIND Amarais 750S Laser LASIK eye technology

The eyes can involuntarily move in all directions for milliseconds while fixating on the laser light. The SCHWIND AMARIS 750S eye tracker monitors the position of the eye with approximately 1050 measurements per second and thereby compensates any deviation up to the sixth dimension.

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 swell, however, the buoy tilts to the side. Furthermore, a buoy also turns around its anchorage or moves upward and downward. In the same manner, your eyeball can roll (rotation), rotate around its own axis (cyclotorsion) or move up and down along the z-axis. The eye tracker of the SCHWIND AMARIS 750S detects all these eye movements and compensates them. With cyclotorsion control, the compensation occurs statically, between the sitting and lying positions of the patient, and dynamically during the laser treatment.

Picture of representation of permanent measurement of corneal thickness for the SCHWIND Amarais 750S Laser LASIK eye technology

Permanent measurement of corneal thickness
Similar to a diver orientating himself in water with his depth gauge, your doctor is permanently informed through the online pachymetry of the SCHWIND AMARIS 750S. This system measures the changes of corneal thickness in real time and displays them on the treatment screen. Thus, your doctor knows at every point in time how much tissue he has already ablated and how thick the remaining cornea still is.

Exceptionally fine laser beam
The laser beams of the SCHWIND AMARIS 750S have an exceptionally small diameter of only 0.54 millimetres and are thus significantly smaller than others. Further-more they have a special shape. Your cornea becomes especially smooth with this fine beam. Constant microclimate With the SCHWIND AMARIS 750S, two specially formed nozzles ensure a directed, fine airflow that creates a stable microclimate across the cornea. The climatic conditions remain constant, preventing the cornea from drying out.

Unique thermal control
The SCHWIND AMARIS 750S is equipped with a unique thermal control system. Even at high ablation speed the corneal tissue is effectively preserved. The laser pulses are temporally and spatially sorted, which gives the individual position on the cornea sufficient time to cool off. Following pulses can thereby approach an already cooled position faster.

Clinical results
A multitude of international clinical studies have documented the excellent treatment quality with SCHWIND AMARIS technology. Visual acuity of 100 percent or better was achieved in nearly all cases.

A high percentage of treated patients could see better than before with glasses or contact lenses.

The study results also show improved contrast vision.

SCHWIND AMARIS® 750S - Clinical Results

SCHWIND AMARIS® - Frequently Asked Questions (FAQs)


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