Advanced Perth Laser Vision Correction Technology - LASIK SMILE and PRK

Laser vision correction has been the gold standard vision correction surgery for over 25 years. In this period 2 types of vision correction lasers have become available.

Excimer laser is the first type to be used for vision correction. This type of laser vaporises corneal tissue on direct contact. It can therefore sculpt the cornea into a different shape like a sander on a block of wood. However, it can only work directly on an exposed corneal surface necessitating skin debridement (PRK) or a corneal flap (LASIK) before treatment.

Femtosecond lasers are a newer type of laser. Femtosecond lasers are very accurate internal corneal cutters. They can incise a complex shape within clear tissue without disturbing the surface. This is achieved via a very small explosive effect at the focal point of the laser causing tissue sepration.  A Femtosecond laser is a laser with a very, very short pulse duration.  These very short explosive pulses allow the laser to use very little energy to incise within the cornea without affecting surrounding tissues.  

A femtosecond laser can create a three dimensional cut within the cornea with high precision very quickly and with no injury to the delicate surface of the eye. This is similar to popular souvenir glass blocks with complex 3d shapes etched inside of it by a 3D laser.This type of laser is used in flap cutting in LASIK eye surgery and SMILE eye surgery.  Femtosecond laser has essentially replace the older oscillating blade in Perth LASIK surgery for several years.  Femtosecond laser can also be used in corneal transplant surgery and kera-ring implantation.

The difference in excimer laser surface effects and femtosecond internal cutting effects

The Zeiss Visumax Femtosecond laser a breakthrough in Perth laser vision technology

The Zeiss Visumax femtosecond laser is the most advanced corneal laser in the world.  It uses a gentle curved patient interface for less patient discomfort and higher accuracy due to less tissue distortion. Also the laser beams are highy concentrated to minimise damage to surrounding tissue allowing higher precision.  The Zeiss Visumax laser has 1 micron spot sizes and fires half a million times per second. These attributes are some of the reasons behind the fact that only the Zeiss Visumax Laser can perform SMILE procedures.   

Other than SMILE treatments, the Visumax also perform flap creation during LASIK in Perth Eye Hospital. It can also be used to assist Keraring implants and corneal transplantation surgery.

We are proud to be the only clinic to offer Zeiss Visumax SMILE laser eye surgery in Perth using this laser.

Zeiss VIsumax laser in Perth Eye Hospital

Femtosecond Laser Patient Interface

Unlike the excimer laser, femtosecond lasers use a suction patient interface to fixate the eye during treatment.  This ensures the most accurate treatment result.

Different femtosecond lasers use different types of interfaces.  The Zeiss Visumax laser uses an advanced curved design.  This type of patient interface is the very gentle as the cornea doesn't have to be deformed, a low pressure suction can be used on the anaesthetised cornea.  Also laser spots are more accurate as the cornea is less distorted allowing less energy used and less collateral injury.  The benefit is a painless gentle experience with higher accuracy.

Other current popular femtosecond lasers use flat interfaces.  These systems require complete flattening of the cornea.  As a result, high power suction needs to be applied to the conjunctiva (the white of the eye) which is not fully anaesthetised.  With these older lasers, there is more pain during surgery and much higher chance of bleeding around the eye after the treatment.

Curved patient interface on Zeiss Visumax femtosecond laser

Flat patient interface on AMO Intralase or Alcon FS200 femtosecond laser

 

The Allegretto Wavelight Excimer Laser

This is one of the most advanced and relaible excimer laser in the world.  This excimer laser scans the eye over 1000 times per second and the laser spots are applied over 400 times per second. Treatment time is very short as a result. Treatment result is also very accurate.

The Wavelight laser offers a range of treatment option including wavefront optimised treatments. This platform also allows for topographic guided treatment profiles and custom aspherical shape profiles for blended vision treatments.  

The variety of treatment adjustment is very usefule for therapeutic laser treatment on abnormal corneas.  This flexiblity is also a huge benefit for LASIK treatments for myopia, hyperopia, astigmatism and presbyopia.  This is the main laser we use in for LASIK in Perth Eye Hospital.  

Allegretto Wavelight eyeQ 400 excimer laser

Treatment profile

Wavefront Optimised Laser Ablation Profile

Modern excimer lasers are small spot lasers with very fast repetition. The treatment spots are applied as a 3 dimensional shape to the cornea to change the shape of the cornea. This 3 dimensional shape of laser spots is called a treatment profile.

This profile is prescribed by the LASIK surgeon tailored to individual patient test result such as refraction, topography, pupil size.

We use wavefront optimised treatments as standard treatments for Aculase Perth LASIK. Wavefront optimised treatments offer better night vision and contrast.  

Special customised aspherical treatment profiles are used by our  for blended Aculase Perth LASIK treatment for presbyopia.  This advanced treatment profile allows for controlled widening of focus distance for much better toleration of blended vision in patients with reading glasses problems.

Wavefront optimised profile minimising induced Spherical Aberration 

Eye tracking

One of the obstacle for patients considering Laser vision surgery is the fear of poor result if they move their eye during surgery. With modern excimer lasers like the Allegretto Wavelight, the laser literally follow the eye during the very short treatment.

The treatment computer lock-on to realtime position of the eye and rapidly adjust the laser beam direction during treatment. As a result, the laser automatically compensates for any movements during the treatment. This is to ensure that the treatment profile is accurately targeted on the cornea during LASIK.

excimer laser eye capture and eye tracking 


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