The Alcon WaveLight Allegretto Excimer Laser
Serving Orange County, California and Surrounding Communities
These are exciting times. When engineers work with leading eye surgeons, the results are spectacular. The Allegretto laser was developed in Germany with a close interaction between developers and end users. It was conceived with wavefront principles in mind.
Some Basic Laser Facts on Allegretto
All lasers are man-made lights. They are generated inside a tubular space at the time they are used and differ from other lights such as flashlights in that they are focused, not scattered. Their light travels in parallel waves, which makes them very precise.
There are many kinds of lasers and those used for vision correction (called excimer lasers) are designed to ablate (remove, vaporize) unwanted tissue from the designated treatment area without affecting any other eye tissue. They are pulsed, meaning that they send very rapid bursts of light, and they can be set to different intensities and depths of penetration. They have a very narrow diameter – that is, a small “spot”.
Speed, Safety, and Precision
The Allegretto developers started with a new concept of flying spot laser treatment. A flying spot laser moves according to involuntary eye movements during treatment; for more, see Accurate Eye Tracking System below. This new version is called PerfectPulse Technology® and the developers used it in combination with wavefront diagnosis.
This makes the laser treatment more accurate because it is based on a more detailed diagnosis. It also makes it faster. Maintaining the normal prolate (oval) shape of the cornea avoids the night time glare and halos common with use of older generation lasers.
In the year 2000, Prof. Theo Seiler and his team performed the first global wavefront-guided treatment using this technology. Only three years later, the ALLEGRETTO WAVE® Excimer Laser became the first system to receive concurrent FDA approval for myopia and hyperopia along with the widest range of approvals ever granted to a new laser platform (technology system). Please see our page on LASIK with Wavefront for more about Custom LASIK.
Accurate Eye Tracking System
Our eyes are constantly making small, rapid jumps called saccadic eye movements. These are beyond human control and may affect the result of your surgery by slightly moving the treatment area. The Allegretto system tracks saccadic eye movements during treatment and moves the laser beam as necessary to keep it accurately focused and to increase patient safety. That is why it is known as a flying spot laser. The eye tracker is an infrared, high speed, precise beam with a response time of less than six milliseconds. It is similar to the VISX system’s Iris Registration feature.
The Laser Beam Profile
A narrow laser beam is said to have a small spot size, and this is very important for both accuracy and smoothness. Research has shown that the ideal beam size is one millimeter or less. The type of laser beam used is also crucial. The best type is a beam with minute variations of strength that form a bell-curve if you map them in a diagram. It is said to have a gaussian profile, which is the most common profile found in nature. The variations cluster around a central average. A gaussian beam provides a far smoother corneal surface than any non-gaussian beam.
Other Advantages of the Allegretto System
1. System Stability
The most important factor at Khanna Vision when we choose any new laser is the stability of the system. Allegretto gets high marks in this respect. It was developed by Wavelight, Inc. before Alcon took over that company’s U.S. operations. It has a proprietary energy management system that balances energy levels during treatment to ensure that each laser pulse is consistent.
PerfectPulse Technology® provides intelligent laser pulse control independent of the room’s humidity and temperature. This gives superior and more stable LASIK results, decreasing any need for enhancement surgery afterwards. You can read more about LASIK on our LASIK Questions page.
2. Smooth Treatment Edges
The normal curvature of a healthy cornea is prolate (higher in the center) – in other words, it is spherical like a basket ball. Older generations of lasers would remove tissue from the corneal center, leaving a crater there. This created an unnatural, oblate shaped cornea – flattened where it should be curved. This, in turn, created a sharp edge between treated and non treated corneal tissue.
- The sharp edge can result in spherical aberration (error), which degrades the quality of vision, often producing glare or halos at night
- Since corneal surface cells are always replacing themselves, they try to revert to their previous spherical shape, undoing some of the vision improvement
To prevent this problem, the Allegretto laser treats the cornea at its edges as well as in its center. The laser uses proprietary nomograms (mathematical calculation diagrams) to adjust corneal roundness. This gives you a smooth and round corneal curvature based on the anterior curvature readings from your Custom LASIK diagnosis. You will have excellent quality of vision during both day and night.
3. Better Night Vision
The Wavelight excimer laser system was specifically designed to perform wavefront-optimized vision correction. It can treat expanded corneal areas, up to 8mm, which can minimize glare, halos, and other potential night vision problems.
4. Faster Treatment
With a repetition rate of 200 pulses per second, WaveLight’s laser is the fastest on the US market today. It operates three to four times as fast as other competing laser systems with similar spot sizes (0.95-mm).
It can treat one diopter of prescription every 4 seconds. If your prescription for contact lenses is “– 4 D” (moderate myopia), that means your treatment will take only 16 seconds. This rapid but accurate treatment speed dries the cornea out less than a longer treatment would, which improves the predictability of your results. You spend less time under the laser. Dr.Khanna can therefore treat people with larger pupils or high prescriptions (severe myopia) who previously were not LASIK candidates.
In summary, the laser is very reliable, extremely quick, highly accurate, and has a fast-responding infrared eye tracker, ensuring patient safety. The Khanna Vision Institute is proud to provide the Wavelight Allegretto laser. We are committed to providing the latest technology to insure the best possible visual outcomes for our patients.