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iLASIK or Z-LASIK, iFS vs. Zeimer

iLASIK or Z-LASIK, iFS vs. Zeimer

iLASIK or ZLASIK? Intralase or Ziemer Technology? 

iLASIK machine ZLASIK machine


At the Orange County LASIK Institute, our LASIK surgeon and medical director constantly researches and evaluates new LASIK surgery technology. The creation of the corneal flap in LASIK surgery is the first step of the procedure. How the corneal flap is made is an extremely important part of your LASIK procedure. Historically, a flap can be made with either a razor blade called the microkeratome or the all laser Intralase system. The Intralase system was originally created in Irvine and was approved by the FDA in 2001. More recently, a Swiss company called Ziemer came onto the market in 2006. The Intralase has been upgraded five times since its approval for LASIK surgery while the Ziemer is on its second upgrade. They are both vastly safer in our opinion than the microkeratome.

The fifth generation Intralase (iLASIK) and the Ziemer Crystalline laser (Z-LASIK) are the two most commonly used all laser systems that make the all laser LASIK flap in the United States. They are both superior to LASIK Flap creation by the microkeratome. In our opinion, the iFS and Intralase laser is superior to the Ziemer laser due to flap customization capabilities, unique flap architecture and strength, surgeon visualization during flap creation, and proven track history of the the Intralase. This is an analysis of the strengths and weaknesses of the two laser systems by Dr. Pham and why we have chosen the iFS and Intralase technology. It discusses Dr. Pham's opinion and experience with the laser systems and not necessarily of the laser company manufacturers. It compares the most upgraded models of the iFS (fifth generation) and Ziemer Crystalline LDV upgrade. Both upgrades have significant improvements over their predecessors.  They both have tremendous advantages over LASIK with a blade.

iFS Advantages over Ziemer:

  • Proven Track Record and History in the United States
  • Full LASIK Flap Customization
  • Consistent Flaps Regardless of Corneal Anatomy
  • Flap Shape and Architecture Leading to Increased FLAP Strength
  • Surgeon Visualization during surgery
  • Increased Corneal and Advanced Capabilities

Ziemer Advantages over Intralase:

  • Lower Operational Costs for Surgeon (retail costs)
  • Faster Internal Rate - However both the iFS (Fifth Generation) and Ziemer (upgraded Crystalline model) make flaps in about 10 seconds. This increased rate does not necessarily decrease the flap making time due to the way that the laser energy is delivered.

Intralase Proven Track Record and History in the United States

  • The Intralase was first approved by the FDA in the United States in 2001. Since then, it has had five major upgrades. It has had time to mature and evolve. The fifth generation was a significant improvement in terms of speed and capability.

Ziemer FDA Approval

  • The Ziemer was approved five years after the Ziemer in 2006 by the FDA. It has had two major upgrades and the current version is the Femto LDV Crystaline Ziemer.

iFS Full Flap Customization and Elliptical Flaps

  • Customization of the Flap gives your LASIK surgeon more options to match your corneal flap dimensions with your prescription and eye size
  • The Intralase can make precise flaps of varying depth and width.
  • The Ziemer can only make flaps of approximately three depths and widths
  • The Intralase Fifth Generaion iFS laser can also make eliptical flaps which are not possible with the Ziemer. Just the option of making a customized elliptical flap shows that increased versatility of the iFS as opposed to the Ziemer.
  • Elliptical flap potential advantages:
    • Distributes forces symmetrically to the elliptical cornea 
    •  Moves the hinge peripherally to maximize stromal bed exposure for full delivery of excimer ablation and reduces chance of ablating the hinge
    • Allows use of a wider hinge angle
    • May spare some corneal collagen fibers to enhance biomechanical stability2

graphic dipicting elliptical flap vs. round flap


iFS makes Consistent Flaps Regardless of Corneal Anatomy and Steepness - Ziemer flaps depend on correct surgeon sizing

  • The Intralase and iFS LASIK technology makes the same thickness and shaped flaps regardless of a patient's corneal anatomy or steepness.
  • The Zeimer uses a special coupling ring that must be correctly sized by your LASIK surgeon.
  • The iFS design reduces surgeon error possiblities since the surgeon does not have the added step of calculating the correct sizing. By making the same flap regardless of corneal steepness the iFS improves the safety of the iLASIK procedure in our opinion. 

iFS Can make an inverted side cut - Stronger Flap Shape and Architecture leading to Increased flap strength in iFS Flaps

  • The iFS can make an inverted side cut. This Z shaped flap edge can greatly increase flap adhesion. The Ziemer flap makes planar flaps and does not have this advantage.

cutting at 150 degrees makes strong flaps

  • The inverted Bevel-In Side cut is customizable up to 150 degrees. This promotes flap strength, replacement, and adhesion. It provides optimal biomechanical stability in the post-LASIK cornea.
  • Only Available in the iFS laser. It is not available for the Zeimer laser or the first four Intralase models
  • Stronger LASIK flaps
  • 3x more flap stability vs. a microkeratome during a flap lift
  • Decreased flap gutter
  • Nerves are closer so there is less loss of corneal sensitivity
  • The Ziemer cannot make inverted side cut angles

Increased Surgeon Control and Visibility - The iFS Intralase laser has real time monitoring for LASIK Flap Creation for increased safety.

  • The Ziemer LASIK flap creation process does not allow the surgeon to view the flap as it is made. The surgeon does not know if a flap is made correctly until AFTER the flap is made.
  • A LASIK surgeon who uses the iFS laser has complete visualization of your LASIK procedure throughtout every step of the LASIK flap creaion. Your LASIK surgeon is able to see your LASIK flap in real time allowing him or her to adjust their technique and the laser to make a perfect LASIK flap for you.

In our opinion, we have invested in the fifth generation iLASIK technology at our practice because of the iFS track record, the full customization of the LASIK flap capabilities, the ability to create an inverted side cut, and the full visualization of the flap making process.

The views expressed are the opinions of our medical director and LASIK Surgeon and do not necessarily represent the opinions of the laser company manufacturers, the FDA, or any governing body. This guide is to help patients learn more about both laser systems and their advantages and disadvantages. Ultimately, the technology a surgeon uses is based on their preferences, experience, and judgement.

The information is from the review of research and literature by Dr. Pham and his office and presents his opinion of the available research up to date as of October 2013.  It does not mean to take the part of the informed consent with a doctor and is used as an educational aide. This is not meant to imply superiority or inferiority of a laser system and each surgeon will have different results/skills with each laser system. It is meant to be a summary of one surgeon’s opinions based on review of the literature between two femtosecond technologies.


© All content written and copyrighted by the Orange County LASIK and PRK Institute

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