3 Keys to Success With Wavefront-Guided LASIK
A strict refraction protocol, prudent exclusion criteria, and careful selection of refractive endpoints will lead to better patient outcomes.
BY J. TREVOR WOODHAMS, M.D., F.A.A.O.

Much of the data about wavefront-guided LASIK comes from large clinical trials that have been undertaken to secure wavefront approval. The real test for all new technologies, however, is how well they fare when used in the "real world."

In my practice, we carefully monitored visual acuity outcomes for distance-dominant eyes of our first 113 consecutive patients who were eligible for and treated with VISX's CustomVue platform. We used the system "right out of the box" with little nomogram adjustment. Our results surpassed both the VISX FDA trial results and our own conventional outcomes using a Refractive Surgery Consultant-optimized (RSC-optimized) nomogram. We achieved these excellent results because of our strict refraction protocol, prudent exclusion criteria, and careful selection of refractive endpoints. In this article, I'll explain why these are key to wavefront success.

Nearly 75% of our patients were 20/16 or better, and almost a third were 20/12.5 or better with CustomVue.

Quality Control Gets Good Results

Careful attention to refraction discrepancies provides a strong element of quality control. We carefully compare the WaveScan and manifest refractions. Accurate evaluation of discrepancies between the manifest refraction, cycloplegic refraction, and wavefront refraction depends on the significance of the discrepancy and the direction in which it occurs -- minus or plus. If there's a discrepancy between the manifest and wavefront refractions of more than 0.5D in sphere or 0.75D in cylinder, we re-refract using the WaveScan refraction as the starting point. If the discrepancy is reduced or the patient accepts the WaveScan refraction, we perform a wavefront ablation. If the discrepancy continues and the patient prefers the manifest refraction, we perform conventional RSC-optimized LASIK. Although nomogram adjustment is limited to sphere, slight adjustments can be made for age and to minimize any MR/WS discrepancy. I will not use wavefront if I have a patient who could end up plus (hyperopic or overcorrected) because an overcorrected myope cannot be retreated. However, undercorrected myopes are good candidates for wavefront enhancement. CustomVue provides a number of limited-range, royalty-free wavefront enhancement cards. If there's a disparity, such as a whole diopter difference between two refractions and I can't account for the difference, I will do conventional LASIK. We find that a sustained discrepancy between the WaveScan and manifest refractions excludes about 5% to 7% of our patients. It's essential not to proceed with treatment until the reason for the discrepancy is understood because these patients will most likely be unhappy with a custom procedure.

When considering differences in the refractions, keep in mind that patients under 35 years of age often over-accommodate during the WaveScan refraction, and techniques to relax accommodation may be necessary. The WaveScan cylinder refraction is highly accurate. When the manifest refraction shows more cylinder, we have found this is often coma masquerading as lower-order cylinder.

	In our practice, the percentage of patients reaching 20/16 with CustomVue is 73% compared with the conventional rate of 44%.

Choosing Which Patients to Treat

Not all our patients will qualify for wavefront treatment. The biggest exclusion factor is the patient doesn't fall within FDA-approved parameters for this procedure. Until the indications for CustomVue wavefront treatment are expanded with FDA approval, our patients with a spherical equivalent greater than -6.5D or cylinder over 3D only have the option of a conventional procedure.

For those patients who fall within acceptable dioptric parameters, a significant disparity between manifest and wavefront refraction is the main reason for exclusion. For example, I might exclude a patient because we are getting a -1.25D on her manifest refraction, while her wavefront is measuring a simulated -2.5D. That's a significant difference, and until I can explain that difference, I am reluctant to treat her with wavefront. The most common reason for this situation is probably ciliary spasm, which can be relieved with proper coaching or preoperative Valium administration. We are also investigating remeasurement with moderate-strength cycloplegics, although it is controversial.

A custom procedure may not be an option for patients with presbyopia, for example our older patients who want monovision but need more than -0.75D of monovision. Since adjustment is limited to undercorrection by -0.75D, higher degrees of myopic monovision are not available despite the presence of coma and other higher-order aberrations. Failure to discontinue contact lens wear for a sufficient premeasurement interval can also disqualify a patient. We require patients to stop wearing soft contact lenses for at least 2 weeks prior to surgery, and gas perm lenses must be out for 1 week for every decade of use. Because we can't confirm compliance, we counsel patients on the risks associated with noncompliance.

Many Factors Count in Setting Endpoints

In setting refractive endpoints, we take age, lifestyle, and the patient's visual needs into consideration. In terms of setting target goals for making adjustments, the most important factor is age. I find that patients under 30 seem to be more satisfied with their outcome if they have a little bit of plus, perhaps +0.25D to +0.50D. If they don't, night vision complaints are likely. Young patients not only can accommodate through a little plus, they also have the advantage of being able to "fine-tune" their focus for varying light conditions and undercorrected higher-order aberrations. Conversely, if you have patients in their 50s and you make them a little plus, they may be unhappy because they will not have crisp distance vision and will find it difficult to compensate through accommodation.

The patient's hobbies and sports activities are also important. For example, if you have a patient who is not active in any sport, you may want to pay more attention to monovision and near vision. However, if you have an avid golfer, binocular distance vision should be your goal. The Atlanta area is home to many avid golfers who, I find, do poorly with monovision. They have to track the golf ball across a low-contrast sky, which requires optimized binocular distance vision, particularly in the presence of early lenticular sclerosis. The need to see that golf ball can be an important predictor of their ultimate satisfaction with the refractive procedure. Recognizing a patient's visual goals is paramount in achieving the kind of satisfaction that motivates referrals.

Our Wavefront-Guided Results are Better

I can easily say our wavefront-guided results are better than our conventional results even with an optimized nomogram. We recommend CustomVue wavefront-guided LASIK now to all eligible patients with few exceptions. Although more demanding of time and commitment to detail, careful attention to refraction protocol, exclusion criteria, and refractive endpoints will product better acuity outcomes and reduce night vision complaints.

Dr. Woodhams is in private practice at Woodhams Eye Clinic in Atlanta, Ga. Although not a paid consultant to VISX, travel and speaking expenses are occasionally subsidized. Contact him at (770) 394-4000 or trevorw@mindspring.com.