Intralase Femtosecond Laser
Traditionally LASIK flaps were made with a mechanical cutting device called a “microkeratome.” In fact, Dr. Schlichtemeier was one of the first American surgeons to use a microkeratome and learned to do so from the inventor of the technology, Dr. Barraquer, in Colombia, South America.
However, today the safest and most precise approach to making a LASIK flap is to use a femtosecond laser. Dr. Schlichtemeier and Dr. Kugler specialize in all-laser bladeless LASIK using the Intralase Femtosecond laser to create the LASIK flap.
Maintaining the integrity of the corneal biomechanics is a critical element in the success of the refractive procedure, and the Intralase femtosecond laser system delivers unmatched control over flap diameter, depth, centration and morphology, resulting in an unprecedented combination of potential advantages, including:
- Controlled Flap Structure
- Precisely centered, accurately sized flaps; programmable hinge placement
- Flap dimensions designed based on patient factors, such as corneal thickness, steepness, diameter and pupil position
- Precise control of flap dimensions helps avoid the peripheral lamellar structure, vital to the biomechanical stability of the cornea
- Uniform Flap Thickness
- Uniformly thin, planar flaps
- Smooth, evenly hydrated, stromal morphology
- Reproducible flap thicknesses with profiles that are significantly superior to those achieved by mechanical means (p<0.001)
- Maximized residual stromal beds
- Superior Visual Outcomes
- Rapid visual recovery
- Better visual acuity on Day 1
- Month 1: Increased contrast sensitivity at all spatial frequencies vs. baseline (n=88)
- Better quality of vision
- Eyes treated with the Intralase FS Laser System had fewer visual disturbances (haze, glare, sensitivity), less pain, and less dryness than surgeries performed with a blade.
- Retrospective analysis comparing LASIK results with Intralase Technology versus the two leading blade microkeratomes available demonstrated that Intralase performed better in three areas important to LASIK results and safety: flap thickness, induced astigmatism, and cell injury. There are fewer flap-related complications with the bladeless method:
- Minimal risk of sight-threatening events
- Lower risk of corneal abrasion
- Reduced risk of dry eye
Allegretto Wave EyeQ Excimer Laser
Overview
The Wavelight Allegretto Wave EyeQ laser is the most sophisticated, and best designed laser available for vision correction surgery. This laser was designed from top to bottom for laser eye surgery, and does not “borrow” its laser technology from lasers used in other industries, as do some other lasers on the market. It was designed much more recently than other systems on the market, including the Visx, Technolas, and B&L systems, thus does not have a series of “band-aids” or add-ons to correct early deficiencies. It was designed to be high-performance from the very beginning.
The Allegretto Wave EyeQ is manufactured by Wavelight, a German laser company determined to make lasers for vision correction that have the best precision and accuracy. Dr. Kugler often compares the laser market to the car market: though some of the initial engineering and manufacturing of cars was performed in the United States, several years later cars from German companies such as BMW, Mercedes, Audi, and Porche emerged from the pack as the leaders in high performance and high quality. The same is true of the eye laser market, as Wavelight has emerged as the highest quality eye laser available.
Using “PerfectPulse” technology, the Allegretto EyeQ laser controls every single laser pulse. Doing so allows the Allegretto EyeQ to be the fastest and most precise laser system available.
This laser provides Wavefront treatment for EVERY procedure, and does not require the patient to pay extra or “add-on” the wavefront treatment as do other laser systems. In fact, much of the marketing and discussion of “wavefront technology” in the laser surgery field can be very confusing for patients. Wavelight takes away the confusion by providing a wavefront-optimized treatment for EVERY eye using a system called High Performance Vision Correction. This system improves the quality of vision in all lighting conditions, including nighttime lighting.
Some of the features that help differentiate and distinguish the Wavelight Allegretto EyeQ laser from the competition include the following:
- Exceptionally stable laser engine, resulting in very stable performance;
- Extremely precise calibration. The laser is calibrated before every treatment.
- It’s the only laser system to address the cosine correction offset problem
- It’s the only laser to take into account the specific curvature of the patient’s eye, with the intent to preserve the naturally aspheric “prolate” corneal shape after treatment;
- Clinical data presented to the FDA showed that patients’ quality of night vision after treatment was better than patients’ quality of night vision before treatment
However, despite all of this impressive data regarding the Wavelight Allegretto EyeQ laser, the results are only as good as the surgeon operating the laser. Similarly, just because a 747 is a sophisticated and well-designed airliner does not mean that the average pilot can fly it successfully without proper training and experience. Drs. Kugler and Schlichtemeier are experts in all aspects of laser eye surgery.
Safety
One of the most common concerns people have about laser eye surgery is whether the treatment is safe. There are four aspects of laser eye surgery that contribute to its overall safety:
- Proper patient evaluation before surgery
- Creation of the LASIK flap
- Laser technology
- Proper Post-operative care and follow-up
Here, we will address here the issue of laser technology in this section, as the other issues are discussed elsewhere in the site.
All lasers approved by the FDA for use in vision correction must demonstrate a certain level of safety. These include, but are not limited to, the following:
- Electrical power backup in case of a power outage
- Calibration at the point of treatment
- Design of built-in safeguards that will pause treatment if necessary, should there be any malfunction detected within the laser, with the ability to resume treatment from where it was paused
- An eye-tracking system that follows eye movements and adjusts the laser energy delivery accordingly. The laser must pause if the eye moves too far from the center of the laser.
- Extensive documentation of operation, service and maintenance
The Wavelight Allegretto EyeQ laser takes these minimum requirements a bit further. The laser eye tracker is very sophisticated and fast, thus subtle eye movements are closely tracked and compensated for by the laser. Furthermore, the laser core is extremely stable, meaning that the energy delivered by the laser is very predictable for each laser pulse. Lastly, the Allegretto is the fastest laser available, and that means the treatment time and energy delivered is as low as possible.
Speed, and Precision
The Wavelight Allegretto EyeQ operates at a speed of 400hz, which means the laser fires 400 times per second. This is more than four times faster than other laser systems. The reason speed is important is that it increases the precision of the treatment. The cornea is made out of collagen and water. When the LASIK flap is lifted, the water evaporates over time. If too much water evaporates then the laser removes too much tissue and the result is not as accurate. A fast 400hz treatment means that the amount of time the flap is lifted is significantly less, which means less water evaporates and the precision of the treatment is enhanced.
Each time the laser fires, it removes a microscopic amount of tissue. By removing small pieces of tissue in a predictable pattern, the vision of the eye can be altered. This is the basis for laser eye surgery. The more precise the laser beam is, the more precise the results can be predicted. The Allegretto laser uses a “Gaussian” laser beam profile allowing for a precise, defined application of its energy with each pulse.
The laser core of the Allegretto is extremely stable, which means that the energy delivered by each pulse is reliable and consistent. Furthermore, the entire optical system of the laser is washed out with nitrogen gas between each treatment, which allows for precise optics and performance for each patient.
Eye Tracking
Eye tracking systems are a crucial to success of modern laser surgery. These systems follow the position of the eye during the treatment from start to finish and adjust the location of the laser beam accordingly. Naturally, the Allegretto laser can only treat at its ultra-fast 400 pulses per second if it has a tracking system that is also ultra-fast.
The laser uses an infrared pupil tracking system that determines the exact pupil position once every 2.5 milliseconds. The laser beam is automatically aligned to the pupil position, then it is checked again one more time to confirm the pupil is still in the same place before firing the laser. This happens 400 times every second, once for every laser pulse. If the eye moves too quickly or moves out of the range of the laser beam, the laser will stop and wait for the surgeon to position the eye back in the center. Once the eye is back where it belongs, the treatment resumes where it left off.
This photo shows the eye tracking system as seen by the patient during surgery. These lights monitor the eye’s position over 400 times per second and adjust the aim of the laser beam accordingly.
This remarkably fast and sophisticated system ensures that each pulse of the laser is positioned in the perfect spot on the eye. This system ensures that the treatment will be delivered “on target” every time, with each pulse.
PerfectPulse
The Allegretto laser has been designed to ensure that the amount of laser energy in each pulse is calibrated to a precise, consistent level. Before the laser beam fires, it is measured at checkpoints on its way through the laser system. At each point the energy level is checked and adjusted ensuring the beam is properly tuned before it reaches the eye. This system, called “PerfectPulse,” is one of the ways that the Allegretto delivers a smoother, better, and more natural treatment result than other lasers available for laser vision correction.
Wavefront Optimized Treatment
“Wavefront” is a term that is inconsistently used in much of the information in the field of refractive surgery. This inconsistency can be confusing for patients. This section is designed to reduce that confusion and explain why the Allegretto laser delivers the best treatment in terms of Wavefront optimization.
The simplest way to understand Wavefront is to think of visual symptoms such as glare and halos that are commonly seen by people who wear glasses and contact lenses. Wavefront treatments are designed to reduce glare and halos even better than glasses or contact lenses. Most laser platforms attempt to fix glare and halos that already exist in a patient’s eye before surgery, but the Allegretto laser is the only laser available in the United States that optimizes every treatment to prevent the development of glare and halos after surgery. In this way the laser treatments are designed to provide a lifetime of good vision in all lighting conditions.
A good analogy here is to compare a high-definition TV (think Wavefront Optimized treatment) to a standard definition TV (think older laser technology).
Cosine Offset
Another powerful advantage of the Allegretto platform is its ability to correct an issue known as the Cosine Offset Problem. Lasers are calibrated to ensure that the energy is accurate and consistent. Most laser platforms are calibrated on a flat surface. The human eye, however, is not a flat surface, therefore the laser calibration is not perfectly set for the shape of the eye. This is particularly a problem for the edge, or periphery, of the laser treatment pattern.
The Allegretto system overcomes the cosine offset issue by applying extra laser pulses to the periphery in order to compensate for the angle of the laser beam. This compensation, combined with the “Perfect Pulse” technolog produces a smooth well-designed optical surface.
