In May 2003, the FDA approved VISX, Inc.'s (Santa Clara, CA) CustomVue technology for the treatment of up to -6.00 D of myopia and up to 3.00 D of astigmatism. In this article, Robert K. Maloney, MD, of Los Angeles, and Roy S. Rubinfeld, MD, of Washington, DC, share their experiences with this system (Figure 1) and some projections for the future.

DILATION
CustomVue procedures do not require pupil dilation for data collection, and both physicians appreciate being able to treat eyes in their natural refractive state. Dr. Rubinfeld asserts that the center of the pupil may move slightly upon dilation, because most pupils pharmacologically dilate asymmetrically. This movement, he says, can affect treatment centration. Dr. Maloney adds that dilation can affect the eye's aberration structure and result in an incorrect assessment of the patient's true, nondilated aberrations. This error may lead to a suboptimal correction, he says. In addition, Dr. Rubinfeld states that dilating drops used 30 minutes preoperatively versus immediately prior to surgery can increase the likelihood of epithelial disruption during the microkeratome pass and flap manipulation. Finally, when performing surgery with the LADARVision System (Alcon Laboratories, Inc., Fort Worth, TX), Dr. Rubinfeld found that microscope illumination caused the pupil size to decrease in a few of his younger patients, a situation that forced him to abort the procedures.

According to Dr. Maloney, the single disadvantage of not dilating patients is that some develop instrument accommodation during wavefront measurements. If a patient appears to be accommodating (eg, if the wavefront measurement is more myopic than the manifest refraction), Dr. Maloney will often perform mild cycloplegia.

TOPOGRAPHY
Although the CustomVue system does not currently use surface topographic information, Dr. Rubinfeld states that VISX, Inc., is considering incorporating this data in the future, particularly for use with postoperative patients. Dr. Maloney, however, does not see the value of this potential addition.

“If you look at the equations necessary to do wavefront-guided treatment on the cornea, you can model the cornea as an asphere and get an extraordinarily accurate ablation regardless of the specifics of topography,” he says. “My personal opinion is that topography-assisted, wavefront-guided treatment is merely of marketing value, not of medical value.”

CLINICAL EXPERIENCE

Time and Pricing
Incorporating customized ablation technology into his practice required Dr. Rubinfeld to dramatically alter the sequence in which he sees patients, performs examinations, and collects preoperative data. He finds that the entire process of delivering customized ablations is more time consuming compared with conventional LASIK. As a result, he initially saw approximately 20% fewer patients. With experience and the hiring of additional staff, Dr. Rubinfeld's volume has returned to its usual level.

Dr. Maloney's preoperative flow also slowed by approximately 20 minutes per patient for wavefront capture and analysis. His solution was to dedicate a technician to wavefront data collection, and his patient flow has essentially returned to previous levels.

Both physicians charge a higher fee for customized procedures. Dr. Maloney's and Dr. Rubinfeld's prices for CustomVue procedures are $400 and $500 more per eye, respectively, versus conventional LASIK.

Candidacy
Both surgeons attribute rises in their procedural volumes to the incorporation of customized ablation into their practices. Dr. Rubinfeld believes that fear sidelined a large number of LASIK candidates, but he thinks that increasing evidence of LASIK's safety and the excellent data on customized ablations (particularly as regards potential nighttime vision problems) has prompted many to pursue refractive surgery. Dr. Maloney concurs and says CustomVue has enabled him to feel more comfortable treating patients who are concerned about nighttime glare and halos.

Expectations
Dr. Maloney points out that the original promise of customized ablation was to reduce the amount of preoperative aberrations when correcting an eye's refractive error. While he acknowledges that all laser systems to date have actually failed in this regard, he notes that customized ablation induces significantly fewer higher-order aberrations than standard LASIK. He firmly believes that surgeons' ability to measure patients' pre- and postoperative aberrations has dramatically improved their ablation profiles.

In fact, Dr. Maloney says that he is astonished both by the continually improving accuracy of surgical results and the accompanying elevation of patients' expectations. When he began performing refractive surgery in the early 1990s, Dr. Maloney and his colleagues considered a refractive outcome of -0.50 D after RK to be excellent, and his patients were well satisfied. With PRK and during the early days of LASIK, he says surgeons were happy if 90% of patients attained 20/40 vision postoperatively.

“Now, we're getting 95% of people to 20/20 with the VISX system, and we think that's excellent,” he says. “The amazing thing is that I wouldn't say that patient satisfaction keeps rising over the years. As our results have gotten better, we've been more comfortable treating more difficult cases, and we've found patient expectations rising right along with our ability to treat them.”

Although he, too, is greatly impressed by customized ablation's superior results, Dr. Rubinfeld follows a policy of underpromising and overdelivering on outcomes in an effort to maintain high levels of patient satisfaction.

TIPS
Dr. Rubinfeld recommends beginning preoperative patient evaluations with the wavefront refraction, rather than glasses or the standard manifest refraction. He then suggests refining the measurement in order to produce the wavefront-adjusted manifest refraction or WAMR. When using the physician adjustment function, Dr. Rubinfeld considers the patient's eye dominance, age, and wavefront-adjusted manifest refraction. In order to counter cyclotorsion, he recommends marking the 3- and 9-o'clock positions while the patient is sitting upright.

THE FUTURE
Both physicians excitedly report that iris registration and tracking, which will account for cyclotorsion, should be available for the CustomVue system within the next few months. Dr. Maloney believes that these additions will greatly improve the accuracy of treatments for higher-order aberrations and astigmatism. He also looks forward to the pending release of new algorithms for reconstructing regular corneal surfaces as a means of delivering more precise therapeutic wavefront-guided ablations.

Additionally, Dr. Maloney reports that investigators have completed the FDA study for hyperopia and will soon submit the data to the FDA. He says researchers are in the process of collecting FDA data for mixed astigmatism and hope to submit it within 6 months. Dr. Maloney says a study of high myopia (> -6.00 D of spherical equivalent myopia) is also planned, and the company hopes to receive an expansion of the refractive sphere physician adjustment from the FDA to treat monovision. He notes that, although it is possible to undercorrect by 0.75 D, surgeons performing CustomVue procedures cannot perform a monovision undercorrection with the current FDA-approved software parameters. Dr. Maloney believes that the ideal refractive procedure minimizes aberrations, but he comments that aberrations are less problematic with monovision than distance vision. For that reason, he says conventional treatment is relatively closer to wavefront in efficacy for monovision.

Regarding whether he foresees a limit on the ranges of correction for customized ablation, Dr. Rubinfeld notes that preoperative corneal thickness and keratometry readings place boundaries on any form of laser ablation. His great hope is one day to be able to help larger numbers of post-LASIK patients with disappointing surgical results due to higher-order aberrations and/or subjective visual problems.

Robert K. Maloney, MD, is Director of the Maloney Vision Institute in Los Angeles. He is a consultant for VISX, Inc. Dr. Maloney may be reached at (310) 206-7692; drmaloney@maloneyvision.com.
Roy S. Rubinfeld, MD, practices at Washington Eye Physicians and Surgeons and is Clinical Associate Professor at Georgetown University Medical Center in Washington, DC. He does not hold any financial interest in the product and company described herein. Dr. Rubinfeld may be reached at (301) 654-5290; rubinkr1@aol.com.