BLOG: High-definition wavefront-guided PRK
For refractive surgery practices, wavefront-guided, or WFG, LASIK is the mainstay of treatment, thanks to its broad treatment parameters and reputation for patient comfort and rapid visual recovery. But not everyone is a candidate for LASIK. Surface ablation is a great alternative for those who have thinner corneas, but that sometimes means an uncomfortable choice between a state-of-the-art WFG procedure and a conventional or off-label one.
Fortunately, the FDA recently approved a new, high-definition wavefront aberrometry-guided system for PRK, the iDesign system (Johnson & Johnson Vision). The clinical trial that led to approval was conducted by military refractive surgeons, who probably perform more surface ablation procedures annually than any of us in private clinical practice.
Like its predecessor, iDesign uses a Fourier reconstruction algorithm and Hartmann-Shack technology, but it has a greater dynamic range, captures five times as many data points (up to 1,200, depending on pupil size), and incorporates simultaneous measurement of refraction, topography, keratometry and pupillometry, so that all these measurements can be spatially registered to each other. Built-in corrections for infinity and for chromatic aberration of the laser light have brought the wavefront refraction closer to the true refraction and reduced the need for nomogram adjustments. Studies of this system for LASIK have shown greater patient satisfaction and a higher percentage of eyes seeing 20/16 or better compared with WaveScan-guided LASIK.
In the multicenter PRK study, 334 eyes of 167 subjects with myopia or myopic astigmatism were treated. The mean age was 26.6 years (range, 19 to 47 years), and 68.3% were male. The preoperative mean manifest refraction spherical equivalent was –4.08 D (–0.63 D to –8.75 D), with mean cylinder of – .00 D (0 D to –4.00 D).
At 6 months, 322 eyes were available for follow-up. All the eyes were 20/40 or better uncorrected, and an astonishing 92% were 20/16 or better (Figure 1). More than 85% of eyes were within 0.5 D of emmetropia, and more than 96% were within 1 D. Safety endpoints were met, with less than 1% of any adverse event. Complaints of night vision symptoms were slightly improved postop compared with preop, as we have seen in other studies. Most patients (96%) said they either did not experience night vision symptoms or were not bothered by them.
This data and the approval for wavefront-guided PRK provide a great addition to our treatment armamentarium for those patients who are good candidates for surface ablation.
Hofmeister EM, et al. Wavefront-guided photorefractive keratectomy (PRK) for myopia correction: Effectiveness and safety. Presented at: American Academy of Ophthalmology annual meeting; Oct. 11-15, 2019; San Francisco.
Disclosure: Waring reports he is a consultant for Johnson & Johnson Vision and a member of the Johnson & Johnson Vision optics advisory board.