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All LASIK is Not Equal

Patient experience with LASIK can vary extensively based on laser centers, equipment and surgeons. We’ve recently heard a prime example of how patients’ experiences with LASIK can differ. In some centers, patients have an alarming experience as they have to walk with severely impaired vision from the laser that creates the flap to another laser to complete their procedure. Our patients never have to move between lasers.

It seems surprising then, that many patients believe that LASIK is the same no matter where they have their procedure and that the only variable between centers is cost. Nothing could be further from the truth. Differences include the accuracy of pre-operative measurements (which directly affects the post-operative visual results), blade vs. femtosecond laser flap creation, the lasers themselves and, of course, the surgeon.


Pre-operative accuracy of the correct prescription is paramount. Without an accurate doctor’s refraction (as opposed to a technician refraction), results cannot be accurate.

Flap creation.

Surprisingly, some surgeons still use a blade for flap creation. Flaps created this way are typically much thicker than those created with a femtosecond laser, resulting in a lower margin of safety against ectasia (progressive thinning of the cornea that might end up requiring a corneal transplant) as well as greater problems with postoperative dryness.

Femtosecond lasers.

Yes, there is a difference in lasers. The femtosecond laser is used to create a corneal tissue flap. Two brands of femtosecond lasers are present in the Kentuckiana area. Most facilities utilize the Intralase. This is a stand-alone laser that is sometimes used in conjunction with the VISX laser. In that case, the laser bed is swiveled back and forth several times between the two lasers to complete the procedure. When used with any other laser, including the Allegretto, the two lasers are completely separate, often in different rooms! The patient must walk from one to the other after the flap is created when vision is at its worst. This can be very disconcerting or even terrifying for a patient.

With the Ziemer femtosecond laser (Bennett & Bloom Eye Centers was the first in the area to have this technology), the entire procedure is completed without the patient needing to move at all. Furthermore, the Ziemer femtosecond laser creates the most accurate flap thickness, nearly always within 10 microns of the intended value. That way we can target ultrathin, 100 micron flaps for greater safety and comfort, having minimal, if any, post-operative dry eye problems.

Excimer lasers.

Differences in excimer lasers are greater than one would think. While all have trackers to adjust for eye movement during the procedure, most lasers, including the Allegretto and VISX lasers track primarily in two dimensions. However, Technolas T217z laser that we use tracks all three dimensions plus rotationally. A photograph of the iris (colored part of the eye) is taken as part of the pre-operative evaluation at the Orbscan 2z when the patient is in the upright position (as prescription determinations are done). When patients lie down, eyes will often rotate slightly. The Technolas laser will match the position of the eye when the patient is lying down to the way it was sitting up. Then, if the patient’s eye moves in any direction during the procedure—x, y, z or rotationally—the laser will simultaneously adjust the treatment to match the eye’s position. This tracking ability of the Technolas laser helps us achieve outstanding surgical results.

All lasers have both standard and individualized wavefront based treatment modalities. Choosing between standard and wavefront treatments is based on the amount of pre-existing higher order aberrations (irregularities of the cornea) in the eye to be treated. Be aware of misleading terminology, since sometimes patients think they are getting an individualized wavefront treatment when, in fact, they are not. For example, the Allegretto’s standard treatment is called “wavefront optimized”!

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Surgical skill.

For some reason, many people think that LASIK is performed entirely by the laser with little or no surgeon input. While the lasers are extremely important, surgeon control cannot be underestimated. In large part, positioning and centering the lasers are performed manually. Lifting and, most importantly, repositioning of the flap is entirely manual. This is extremely important, as malpositioned flaps lead to striae (a wrinkle or fold in the cornea) that can severely affect post-operative vision. Surgical skill is even more important in the case of an enhancement, since epithelial ingrowth under the flap is more likely with enhancements. Precise flap manipulation decreases that risk. Furthermore, when ingrowth or other complications do occur, proper surgical management is crucial.

Choosing your LASIK center.

As you can see, choosing where you have LASIK is extremely important. Technology is a significant consideration. At Bennett & Bloom Eye Centers, we have the most advanced lasers and equipment available. Still, the surgeon’s judgement, expertise and hands controlling these instruments are the most important factors in achieving the results you expect. We will talk you through the entire process to explain what you can expect—before, during and after your procedure—to help you have the most pleasant and successful experience possible. If you are considering LASIK, please contact one of our highly trained counselors for more information. Bennett & Bloom Eye Centers…Go Where The Doctors Go!