Laser Eye Surgeries
- LASIK
- LASEK
- WAVEFRONT-Optimised LASIK
Other Refractive Surgeries
- Conductive Keratoplasty (CK)
Cataract Surgery
- Cataract Extraction Overview
- Cataract Possible Complications
Keratoconus Treatment
- Corneal Cross Linking Keratoconus Treatment
Technology
- Technology at the Wellington Eye Clinic
Related Items
10 Reasons to choose Wellington Eye Clinic
Are you tired of reading glasses?
Wellington Eye Clinic Milestones
Treatments
WAVEFRONT-Optimised LASIK
Most patients undergoing laser surgery in the past were very happy with their daytime vision but were aware of lesser quality vision at night or at dawn or dusk. The reason is that all lasers had less effect in the peripheral parts of the cornea and an oblate shape was created that increased glare at night. The Wavelight Allegretto is the only laser that compensates for this by increasing the number of shots in the periphery in order to create a prolate shape. This leads to increased quality night vision.
The diagram demonstrates how a perfect sphere has spherical aberration. For this reason, the human cornea is not perfectly spherical, but rather aspheric. It is steeper in the centre and flatter in the periphery. The Allegretto laser attempts to maintain this relationship between central steepness and peripheral flatness.
EFFECTS OF CORNEAL CURVATURE ON ABLATION PROFILE
The Allegretto Wave compensates for the reduced energy absorption in the periphery with more spots.
Result: True, large optical zone and ability to create a prolate cornea shape
The Problem
A Perfect Sphere
Even a perfect sphere has spherical aberration with the peripheral rays being refracted more than the central ray.
The normal corneal curvature is asperical i.e. steeper at the apex and less steep (flatter) at the periphery.
After regular laser surgery with any laser other than the Wavelight
This treatment has increased the spherical abberation with the peripheral rays being refracted even more than before.
After wavefront-optimised laser surgery (Allegretto Standard treatment)
This treatment has reduced the spherical aberration with the peripheral rays being refracted less than before and all the rays intersecting at the same point.
The Treatment
Wavefront-Guided Treatments
Wavefront-Guided (Customised) treatments are designed to correct higher order errors or aberrations.
This treatment has reduced the spherical aberration with the peripheral rays being refracted less than before and all the rays intersecting at the same point
Wavelight Wavefront Analyser
The Wavelight Wavefront Analyser uses visible light to map the wavefront aberrations as opposed to all other systems that use infrared light. An image is projected into the eye through a dilated pupil (after getting drops) and then the image at the back of the eye is photographed through the central, aberration-free part of the cornea. This photograph is then compared to the image that was projected by software and a digital map is produced of the wavefront. The data is then transferred to the laser to do a customised treatment.
The Technology
This technology can only work if the resolution of the laser is very good. The success of the procedure relies on good diagnostic data (the wavefront map) and the ability to transfer that treatment profile to the cornea (the laser).
Spot size
- Smallest spot size available (0.95mm)
- Increases resolution (accuracy/smoothness)
- Other lasers may claim smaler spots, but they are measuring at a different point within the beam profile
- This is the smallest spot size currently available with any laser system.
The smaller the spot size the higher the resolution (like drawing with a crayon as opposed to using a fine pencil).
The smaller spot size however needs a faster repetition rate to allow the same treatment to be done in the same time. The Allegretto is so fast, that despite having the smallest spot size, it is still the fastest laser available. It treats one diopter every five seconds.
