Article Date: 9/1/2004

patient management
An Introduction To IntraLase LASIK

If you co-manage surgery, then educate your patients in the differences between a microkeratome blade and a laser.
BY ELLA G. FAKTOROVICH, M.D., & SCOTT F. LEE, O.D., San Francisco, Calif.

The IntraLase FS (femtosecond) laser by IntraLase is one of the most significant advances in safety and accuracy for refractive surgery vision correction. This instrument has redefined lamellar corneal surgery by replacing the mechanical blade of a microkeratome with an ultra-fast laser to create the corneal flap for the LASIK procedure. The intraoperative experience and post-procedural care after LASIK with IntraLase is somewhat different, however, than LASIK with the mechanical microkeratome.

In this article, we'll report on the accuracy and safety of the IntraLase FS laser. We'll also share some effective patient management pearls. We hope you find this information useful.

Reviewing the benefits

Published studies report safety and accuracy advantages of IntraLase technology over mechanical microkeratomes, including:

For example, the IntraLase FS reduces the risk of creating a thinner-than-intended flap with a possible buttonhole. It also reduces the risk of creating a thicker than-intended-flap, which improves the safety of the procedure by potentially reducing the risk of iatrogenic ectasia.

More patients achieve postoperative correction within 0.5D of emmetropia and the incidence of induced astigmatism is less with the IntraLase FS. Improved outcomes are apparent in both conventional and wavefront-guided laser vision correction.

Knowing the nitty gritty

The patient's intraoperative experience, the healing course and the corneal appearance are unique to the IntraLase procedure and in some ways different from LASIK with the mechanical microkeratome. Considering the significant long-term benefits of using the IntraLase FS laser, we need to educate our patients about the short-term differences in the procedure.

The intraoperative experience. With IntraLase, the overall time each patient spends in the surgery center is increased, in some cases by at least 40 minutes. It takes 55 seconds per eye to create a corneal flap with the Intralase. The patient then waits about 15 to 30 minutes for the cavitation bubbles to clear before the excimer treatment is performed. The procedure time is extended further when the wavefront mapping is performed prior to the IntraLase step.

We've created a step-by-step guide of what our patients can expect on the day of their procedure and we review the steps with each patient during his pre-op exam. The patients' comfort improves significantly when their expectations match their experience. Also, rather than have their family or friends wait in the center during the entire process, many patients elect to have us call their family or friend when they're ready to leave. Additionally, we set up a comfortable relaxation room for patients to wait in after the IntraLase step. It contains sofas, music, and other features to enhance patient comfort and reduce the anxiety associated with waiting.

The healing course. Some patients may experience discomfort during the IntraLase step because of the increased time the suction ring is applied to the eye (about 55 seconds compared to less than five seconds with a mechanical microkeratome).

Some patients have also noticed eye irritation during the wait time between IntraLase and excimer treatment. We now give them 1 mg to 2 mg of Lorazepam (Ativan) rather than diazepam (Valium) upon arrival for their procedure to reduce anxiety and to enhance comfort during the entire procedure. (Lorazepam is stronger and longer-acting than diazepam. The effect; however, wears off by the next day.)

In some patients, we also add Hydrocodone/Tylenol (Vicodin) to reduce discomfort. All patients have Tetracaine drops placed in their eyes after the IntraLase step. With this protocol, the patients are comfortable and relaxed, reporting positive experience during their procedure.


Figure 1: One week post-op. The edge of the flap may be staining or pooling fluorescein. This finding resolves with frequent lubrication.

The corneal appearance. During the early healing stages, small nests of epithelial cells can occasionally be visible in the side cut (Figure 1). These pool fluorescein and may cause eye irritation in some patients. Both of these findings resolve with time. We recommend frequent use of nonpreserved lubricants for symptomatic patients.

With the IntraLase procedure, we have optimized both the side cut angle and energy to minimize the slit lamp appearance of the flap edge while preserving the integrity of the flap edge security. Even with the side cut angle and energy optimization, the IntraLase flap edge heals better and is often more apparent at the slit lamp than the flap edge created with a mechanical microkeratome (Figure 2).

This has no effect on patient's vision. It does, however, reduce the incidence of epithelial ingrowth, increase the security of the flap and may protect the patient from flap slippage with minor trauma as well as possibly preserving corneal strength and reducing the risk of iatrogenic ectasia.

Special considerations

As with any procedure, special considerations exist that are unique to it. Below are a few considerations that you may encounter with use of the IntraLase FS laser:

Subconjunctival hemorrhages. Occasionally they may be noted during the first week after the procedure. The incidence of subconjuctival hemorrhages is reduced by ensuring slow release of suction when keratectomy is complete and by applying the suction ring to the eye under the microscope to ensure perfect centration the first time.

The subconjunctival hemorrhages have no clinical significance and resolve without treatment. They also have no effect on corneal healing.

Figure 2: One month post-op. The edge of the flap may be visible at the slit lamp. This finding is asymptomatic

Transient photophobia. A small percentage of patients report photophobia several weeks after the IntraLase procedure. The corneas are typically clear. Photophobia generally resolves on its own.

To speed up the resolution of this symptom, patients can use a one- to two-week course of prednisolone acetate q.i.d.

Miscellaneous. Other findings associated with the IntraLase procedure have been described. These include diffuse lamellar keratitis (DLK), prolonged flap edema and slow visual recovery. All of these findings have been related to the suboptimal energy settings on a laser.

We haven't observed DLK greater than grade I in any of our patients. The incidence of DLK with IntraLase is similar to the mechanical microkeratome both in our experience and in the published studies. The incidence of flap edema is similar as well.

Uncorrected visual acuity at all post-op visits is, in fact, better after IntraLase procedure than after LASIK with a mechanical microkeratome.

Keep it in perspective

By managing patients' expectations as well as our own, we can easily adopt this technology, which delivers unprecedented safety and accuracy. Managing patient expectations at the beginning of the laser surgery relationship also makes it easier to co-manage patients because they go into the experience fully aware, thanks to your help.

References available on request.

 

IntraLase at a Glance

The IntraLase FS is a solid state laser that uses infrared wavelength (1053 nm) to deliver closely spaced, 3-µm spots that the surgeon can focus to a preset depth in the corneal stroma to create a circular plane. The surgeon then applies laser energy to the edges of the circular plane at a preprogrammed (side-cut) angle using a circumferential pattern of progressively shallower pulses. An arc along the edge of the flap is left undisturbed to create the flap hinge. The location and width of the hinge is preprogrammed according to the surgeon's preferences and the patient's specific anatomic features.

The short laser bursts (one quadrillionth of a second) result in microscopic cavitation bubbles, which resorbs within 30 minutes. The surgeon then performs the excimer laser treatment (with or without a wavefront map to correct refractive error).

 

Dr. Faktorovich is the medical director of Pacific Vision Institute. She specializes in corneal and refractive surgery.

 

 

Dr.. Lee is clinical care and research specialist at Pacific Vision Institute.

 

 



Optometric Management, Issue: September 2004