OD News Articles

1st July 2009

Are Lasers Best for Making LASIK Flaps?

by Alexander Archibald, OD Great Falls, MT

With the popularity of laser vision correction, many patients have questions about LASIK. If you provide pre and post-operative care for this procedure, you have probably been asked about IntraLase or bladeless LASIK. In fact, patients may come into your office with their minds made up. Bladeless LASIK is what they want—and they are willing to pay for it! But do femtosecond lasers really do a better job of creating LASIK flaps? Unfortunately, consumers and many surgeons have been led to think so.

Our Experience

Having used both techniques, we believe that LASIK flaps created by a modern microkeratome in the hands of a skilled surgeon have certain advantages over laser flaps.

We are not alone. A healthy discussion is underway among refractive surgeons regarding the benefits of microkeratomes vs. femtosecond lasers. I hope this article will put LASIK flap technology in a more balanced perspective.

Microkeratomes

Microkeratomes are highly engineered mechanical instruments that use a blade to separate layers of stromal tissue and create a corneal flap. They work in a similar fashion to a carpenter’s plane. Once the flap is created, it is lifted off the corneal bed without dissection.

► Click to see surgery

► Click to see flap lifting

Microkeratome technology has been highly refined over the years and these tiny instruments cost up to $40,000. Several brands are utilized by refractive surgeons. Having used 7 different models in over 70,000 cases, we have learned from experience that the most popular microkeratome on the market has a higher complication rate than lesser known instruments preferred by our surgeons.

Femtosecond Lasers

Femtosecond lasers utilize ultra short bursts of laser light to create a corneal flap. The laser is programmed to focus within the stromal layer where it vaporizes or gasifies thousands of tiny cavities. Once this is complete, the flap is manually dissected and lifted away from the corneal bed.

Click to see surgery

Click to see flap dissection

Currently, four companies manufacture femtosecond lasers. IntraLase is the most popular and well known. For this reason, femtosecond LASIK flap procedures are often generically referred to as “IntraLase”. Femtosecond lasers are quite large and cost up to $400,000. In addition, surgeons submit royalty payments to the manufacturer for each LASIK flap procedure. Our experience has been with the Ziemer Femto laser.

Big Hit with Surgeons

Femtosecond lasers and bladeless LASIK flaps have become a big hit in the ophthalmic community due to several perceptions. But how much truth is there to the following purported benefits?

  • Lasers cut thinner flaps—While early microkeratomes made 160 micron flaps, most IntraLase surgeons target 110 microns. However, the latest microkeratomes that our surgeons use can create 100 micron flaps.
  • Lasers have greater consistency—A recent study of IntraLase laser flaps showed the average thickness was 100 microns. But the thickness was not consistent and ranged from 57 to137 microns. Click here to see how our own in-house studies compare.
  • Laser cuts are smoother—Femtosecond lasers vaporize or gasify thousands of little cavities within the stromal tissue. While these pockets are close enough together that the flap can then be dissected away from the corneal bed, the edges are not smoother than microkeratome flaps.
  • The flap fits back onto the corneal bed like a manhole cover—While it’s true that the laser cuts vertical flap edges, the flap is so elastic that it does not lay back down and fit tightly like a manhole cover. Laser flaps are still vulnerable to wrinkles and can become dislodged.
  • They are safer—If compared with early microkeratomes or inexperienced users, femtosecond lasers have less complications. But laser flaps can have problems. With the best current microkeratome technology, our surgeons and many others believe the playing field is level.
  • They provide superior results—Unfortunately, published comparative studies do not support this.
Two Ways to Cut

There are really only two ways to cut.

1. Knife

  • Separates without wasting material
  • Leaves smooth surfaces
  • Examples include scissors and scalpels

 

Knife Cut

2. Saw

  • Separates by wasting material (i.e. sawdust)
  • Leaves rougher surfaces
  • Examples include jigsaw, electrocautery instruments

Saw Cut

Even though lasers can be very precise, they cut more like a saw than a knife. They remove tissue by turning it into gas. Femtosecond lasers vaporize a layer of lamellar tissue while microkeratomes simply separate corneal lamellae.

Microkeratome

Strengths

  • Best current designs have significantly reduced complications
  • They make smooth, clean cuts
  • The cut respects the natural corneal lamellar layers
  • No tissue is removed or discarded
  • The instrument is small and easily portable
  • Causes little if any patient discomfort
  • The flap is lifted off the corneal bed without dissection
  • Patients have quick recovery of vision
  • The instrument is relatively inexpensive
  • No royalty charges are required by the manufacturer

Weaknesses

  • Require more skill and experience
  • Designs of early models and many current models result in higher complication rates
  • Temporary haze can occur around flap edge
  • Susceptible to more dramatic complications—especially in less experienced hands
Femtosecond
  • Strengths
  • Inexperienced surgeons will have less complications
  • Complications are less dramatic

Weaknesses

  • A layer of stromal tissue is removed and turned to gas
  • Laser cut does not respect the natural corneal lamellar layers
  • The flap requires manual dissection to be lifted off the corneal bed
  • In our experience, can cause some discomfort to patients
  • Patients have slower recovery of vision
  • Patients are more likely to experience glare from corneal inflammation
  • Instruments are large and not easily moved
  • Instruments are very expensive
  • Instruments are complex and require regular, expensive maintenance
  • Royalty charges must be paid to manufacturers
  • Patients normally pay about $300 extra per eye
Conclusion

Are the benefits of bladeless LASIK worth the extra cost? We don’t think so. Our surgeons seek to create thin and consistent LASIK flaps with as few complications as possible. We want the experience to be pleasant for patients—both during the procedure and as the eye heals. We also want the procedure to be as affordable as possible. Based on our experience with femtosecond laser and traditional flaps, these goals are best achieved with state-of-the-art mechanical microkeratomes.

 

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