If one wants to know how and why the EX 500 Excimer laser is an improvement over prior laser platforms it may be best to outline the characteristics of an ideal Excimer laser used in LASIK vision correction procedures. Unfortunately, some of this material may become technical in nature and it is not necessary for everyone to understand prior to their procedure. It is outlined here for people who would like to understand this technology and serve as a reference source for this groundbreaking technology.
What are the characteristics of an ideal Excimer Laser?
- Precise Placement of Pulses Exactly as Planned
- Consistent Energy Emitted from Laser during Treatment
- Shortest Treatment Times
- Greatest Ability To Neutralize or Adjust for Eye movement
- Fastest Tracking
- Shortest Latency Period (Adjustment Period for Eye Movement)
- Smoothest Ablations (treatments completed with smoothest surfaces)
- Large Optical Zones with Minimal Induced Aberrations ( irregularities)
- Preserve as much original Prolate Cornea Form as Possible (Natural form)
Precise Placement of Pulses Exactly as Planned – Advantages of 1050 Hz Tracking / Short Latency Times
During the first step of the IntraLASIK procedure the corneal flap is made with the WaveLight® FS200 Femtosecond Laser. In the second step, the corneal flap is gently pulled back and a reshaping process occurs using the EX 500 Hz excimer laser. This reshaping process corrects the patients’ nearsightedness, farsightedness and or astigmatism by gently and precisely removing microscopic amounts of tissue and is directly responsible for bringing the eye into focus. The accuracy in the performance of this task is integral to the patient’s quality of vision. During the procedure the patient’s eye is looking up at a green flashing fixation light which helps to keep the eye stable and minimize eye movement. Even so, there is often involuntarily eye movement and the amount of eye movement will vary from one patient to the next. This is where eye tracking becomes very important since it monitors and adjusts for any eye movement, allowing for exact centering over the pupil and precise placement of the planned treatment.
For an ideal treatment to occur, all the pulses of energy will be centered directly over the pupil in a predetermined pattern exactly as planned, consistently and in the shortest period of time so that hydration factors (exposure to air) are at a minimum. If there is eye movement during treatment and it is not adjusted for, it will affect the end result. The WaveLight® EX500 Excimer laser infrared camera monitors and tracks the pupil at 1050 times per second and makes adjustments for any movement at 500 times per second (latency period) or every 2 one-thousandths of a second. This extremely fast tracking and short latency period is well beyond any other Excimer laser ever released in the United States before. It is this extremely fast tracking and short latency period that accounts for greater safety and accuracy in delivering the planned treatment. This tracking is three-dimensional in that it is multi-spatial following the eye in all directions in the XY and Z axises.
The EX500 has the Greatest Sensitivity (compared to any other laser released in the United States) in adjusting to eye movements allowing the greatest precision, placement and safety for the patient.
Consistent Energy Emitted from Laser during Treatment
The EX500 Excimer Laser’s PerfectPulse™ Technology helps assure that the beam energy of every laser pulse is completely controlled from generation to corneal contact.
- WaveLight® actively controls the beam energy at three points, using a smart energy control program.
- The laser energy is contained in a completely sealed nitrogen beam path. The nitrogen prolongs the quality and life cycle of the optics for consistency purposes. WaveLight® laser systems have this feature where many other excimer laser platforms do not.
- Active energy control ensures stable pulse to pulse ablation energy through the entire treatment with energy measurement and feedback control at 3 points.
Shortest Treatment Times
The WaveLight® EX500 Excimer laser treats (ablates) at 500 pulses per second which is faster than any other laser used in the United States. The unmatched fast rate of ablation of the EX500 allows for the shortest treatment times in the world, minimizing the amount of time the patient needs to be on the surgical bed.The speed of the WaveLight® EX500 allows for treatment time of the average nearsighted patient in less than 10 seconds per eye. These consistently shorter treatment times improve patient comfort, decrease patient fixation fatigue and decrease anxiety; while also having inherent medical advantages. Shorter treatment times mean better accuracy because of less variability from tissue exposure and dehydration as well as minimizing other external influences during the procedure increasing predictability and reducing complications. If the corneal tissue is exposed to the environment for a greater period of time, it dries out, and the subsequent Excimer laser treatment can cause an overcorrection.
In summary the most accurate excimer reshaping treatments require short treatment times with minimal exposure of corneal tissue, have the fastest tracking speeds minimizing the effect of any eye movement and have the shortest adjustment time (latency) such as 2/1000’s of a second (or 500 times a second) to adjust for any eye movement.
The WaveLight® EX500 Excimer laser has the shortest treatment times in the world. This minimizes patient anxiety and fixation fatigue. It also minimizes tissue exposure, causing less tissue dehydration, improving the accuracy of the treatment.
Integrated Real-time Non-Contact Optical Pachymetry
Pachymetry in ophthalmology is the measurement of corneal thickness. This can be performed by various means and technologies.Corneal structure and thickness measurements are very important for the doctor to consider when planning vision correction surgery. These measurements play a large role in determining whether or not a patient is a good candidate for LASIK or PRK; or possibly not a candidate at all.
The WaveLight® EX500 laser is the first excimer laser ever used in the United States to have integrated “Non-Contact Real-Time Pachymetry “. This feature allows Dr. Tylock and Dr. George to spontaneously measure and monitor corneal thickness before, during, and after your treatment. It will help to confirm the accuracy of important predetermined measurements during your procedure. This innovative technology is a helpful safety check to see that the femtosecond laser is consistently making its flaps at the predetermined thickness desired, and confirms the total depth of the procedure as estimated preoperatively by the laser software. Additionally, it gives valuable information as to how consistent the doctors’ preoperative estimates are, compared with what is measured directly at the time of surgery. The comparison of these important measurements over time produce a daily, weekly, and monthly means of quality control.
Never before has a surgeon been able to so easily and spontaneously measure his treatment results throughout the entire procedure.
Groundbreaking Advanced Operation Microscope (OPMI) Including Video System
Another unique feature of the advanced WaveLight® EX500 Excimer is an Advanced Operation Microscope with features never seen before. Conveniently placed inside the surgeons’ ocular, the new heads-up display allows several items of important information to be displayed in the surgical field throughout the treatment. The patient’s name, date of birth, and type of treatment planned are displayed throughout the entire procedure which is an important safety measure to ensure the correct patient gets the correct treatment.Also displayed is the quality of the eye tracking and pupil monitoring, optical pachymetry and a treatment progression bar that shows the percent of treatment performed, and percent remaining in an easy-to-read format. The surgeon now has all this important information directly displayed to him without having to look at a separate monitor away from the surgical field. With all prior excimer lasers the doctor would have to look up and away from the surgical field to obtain this information or rely on his technician to verbally tell him what the status is.
Integrated WaveLight® LED Slit Illumination System
An integrated WaveLight® LED Slit Illumination System is designed for lighting the anterior portion of the eye during the entire procedure, as well as, pre-operatively and post-operatively. This allows the doctor to closely inspect the surgical field to detect any abnormalities and ensure that the LASIK flap and its surrounding tissue bed are in perfect alignment.
Dr. Tylock said, “It’s the best slit lamp he has ever seen built into a laser.”