Ophthalmology

Since 2002, when CustomCornea wavefront-guided LASIK (Alcon Laboratories Inc, Ft Worth, Texas) was approved for myopia by the US Food and Drug Administration (FDA), customization has been the main focus of new innovation in refractive surgery. Further FDA approvals of wavefront-guided myopic LASIK were then gained by other laser platforms in addition to approvals for hyperopia and mixed astigmatism. Wavefront-optimized LASIK with the ALLEGRETTO WAVE laser (Alcon Laboratories Inc) was also approved for myopia, hyperopia, and mixed astigmatism in the United States, and topography-guided customized ablations are currently in US FDA trials.

Over the first 5 years, we published sequential supplements sponsored by Alcon Laboratories Inc in the Journal of Refractive Surgery, outlining new developments with customized laser vision correction. Over the past 2.5 years, however, we have been silent. This was primarily because the company was experiencing a transition in laser platforms, which is now more integrated and informative regarding the full extent of customization options for their customer base. With the acquisition of the WaveLight ALLEGRETTO technology, “true customization” has come to mean refractive treatment using a number of possible profiles. At present, the most popular, using the Alcon (Wave-Light) platform, is a wavefront-optimized profile that preserves the natural aspheric shape of the cornea and allows a similar dioptric change in midperipheral and central keratometry. This aberration-neutral correction is effective because of the rapid scanning laser delivery at both 200 and 400 Hz, and because additional pulses are placed in the periphery to compensate for the corneal curvature and difference in angle of incidence of laser pulses.

With this in mind, this year’s supplement focuses on optimized correction with the ALLEGRETTO WAVE laser. In the first article, Dr George and colleagues report the initial experience of wavefront-optimized ablation in a busy academic refractive practice. They outline a typical case distribution of ∼75% LASIK and ∼25% photorefractive keratectomy (PRK). Approximately 25% of the LASIK eyes were targeted for near vision correction so that ∼50% of patients, regardless of age, elected to pursue a monovision outcome. Of those LASIK eyes targeted for emmetropia, 92% achieved 20/20 uncorrected distance visual acuity (UDVA), with 98% achieving 20/25. The percentage of eyes achieving 20/20 did not diminish for higher myopic corrections, in fact, it was 94% for highly myopic eyes (>−6.00 diopters [D]). The aberrometry profile before and 3 months after surgery with the optimized correction reveals no statistical increase in spherical aberration among eyes with low, moderate, and high myopia. This compares favorably with the previous Alcon CustomCornea treatment profile, where only eyes with low myopia had a statistical reduction in spherical aberration, while eyes with moderate and high myopia showed a statistical increase. In transitioning from primarily customized correction using the LADARVision4000 laser (Alcon Laboratories Inc) to optimized correction with the 400-Hz ALLEGRETTO WAVE laser, the authors experienced an overall positive change in visual and aberration outcomes, which may be of benefit to other practices considering a similar transition.

In the second and third articles by Dr Stonecipher and colleagues, the wavefront-optimized results for high myopia and mixed astigmatism are respectively reported using both the 200- and 400-Hz platforms with 3- and 6-month postoperative results. In the study of high myopia from −6.00 to −12.00 D, the percentage of eyes within ±0.50 D of intended correction was 77% at 3 months and 86% at 6 months when using the 200-Hz laser, and 98% and 100%, respectively, when using the 400-Hz laser. This resulted in a greater number of eyes (92%) with UDVA of 20/20 or better with the 400-Hz laser at 6 months, while the percentage of eyes that underwent LASIK with the 200-Hz laser was 77% with UDVA of 20/20 or better. This difference at 6 months was statistically significant for both refractive predictability and visual acuity (P<.01). The results suggest that superior outcomes can be achieved when using the 400-Hz laser and also demonstrate that high myopia can be effectively treated when using this laser platform.

When correcting mixed astigmatism (ranging up to 3.33 D), statistically similar outcomes were observed at 6 months, with 79% and 81% of eyes having UDVA of 20/20 or better with the 200- and 400-Hz systems, respectively. Also at 6 months, 95% and 100% of eyes were within ±0.50 D of intended correction, respectively. The statistically significant difference in vision noted among eyes treated for high myopia that was not present in eyes treated for mixed astigmatism correction may be due to a reduction in the usually long treatment times for high myopia using the 400-Hz system. Although no statistically significant difference was noted in the mixed astigmatism eyes treated with the 200- versus 400-Hz systems, these results are superior to those of other reported studies (see Table on page S822) of mixed astigmatism correction using various customized laser platforms.

In the fourth article by Dr Gordon, a more aggressive laser vision correction profile is considered bilaterally in patients who are presbyopic and desire both distance and near correction. Progressive multifocal LASIK (PML), performed with a femtosecond laser for flap creation, uses an intentionally overcorrected 5.5-mm diameter myopic ablation followed immediately by a 6.0-mm diameter hyperopic ablation to offset the overcorrection. The net effect is a negatively aspheric corneal shape, which expands the depth of focus. Overall, 178 patients received the treatment, and 102 had 3-month follow-up with 81% achieving 20/20 UDVA in both eyes and 98% achieving 20/25 UDVA. Meanwhile, 70% of patients were able to read J1 or J2, while 25% could read J3 and only 5% could read less than J3. Because of the good results Gordon achieved using this procedure, it now accounts for 40% of the total number of refractive procedures at his practice.

In the fifth article, Drs Krueger and Kanellopoulos collaborate on the long-term follow-up of two patients who underwent simultaneous topography-guided PRK and riboflavin/ultraviolet A corneal cross-linking (CXL) for the treatment of progressive keratoconus. The results, which expand upon a subset of a larger study published last year in the Journal,¹ outline in detail the progressive change of topography, refraction, and vision in one eye of two patients (treated by the first author). One eye that fits the typical criteria does extremely well with good stability over 2.5 years, while the other, just beyond the keratometry limit of recommended CXL treatment, experiences a less stable outcome, but one of progressive reduction of myopia and improvement in uncorrected vision. The topographic pattern of change in this patient reveals a central keratometry reading that progressively flattens with time, in line with the improving uncorrected vision, and an inferocentral keratometry reading that progressively increases, suggesting a level of instability and return of keratoconic corneal weakness. Although this second patient may be considered a CXL failure because of the progressive return of the inferior steepening, clinically he is a remarkable success as corneal transplantation was avoided, and at 30-month follow-up uncorrected visual acuity was 20/30. Through this report and the larger study published by Kanellopoulos,¹ clinical success is achievable with simultaneous topography-guided PRK and CXL. Further clinical study and FDA approval of topographic-guided PRK as well as CXL in the United States will hold great potential for the future treatment of progressive keratoconus.

In the sixth and final article, Dr Mrochen and colleagues present technical aspects of the WaveLight FS200 femtosecond laser. This article debuts a new 200-Hz femtosecond laser by WaveLight GmbH (Erlangen, Germany), which similar to the IntraLase femtosecond laser (Abbott Medical Optics, Santa Ana, California), creates a flap with a suction ring and flat applanating cone. This, however, differs in its faster pulse repetition rate, slightly lower pulse energy, tapered alignment of the applanation cone, calibration features, and externalized gas channel for preventing opaque bubble layer, among other features. Testing in 30 porcine eyes reveals a flap thickness resolution of 8 to 10 μm (∼5 μm expected in living eyes) with a lateral resolution of 0.1 μm, intraocular pressure rise up to 150 mmHg during flat glass applanation (comparable to or less than testing with IntraLase flap creation²), and minimal formation of opaque bubble layer due to the optimized scanning algorithm and externalized gas channeling. The laser recently gained CE Mark approval in Europe, and US FDA approval is anticipated for this laser in the near future.

These six articles summarize a progressive expansion in customization in corneal laser refractive surgery and the versatility of technological improvement in the ALLEGRETTO WAVE laser platform.

As the supplement editors, we are indebted to George O. Waring III, MD, FRCS, FRCOphth, who in this year will be retiring from his role as Editor-in-Chief of the Journal of Refractive Surgery after more than 20 years of unbiased and sacrificial service. His contribution to the editorial review of this supplement was significant and points to the outstanding contribution he has made to the Journal during his tenure.

Ronald R. Krueger, MD, MSE, Medical Director, Department of Refractive Surgery, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio

Ravindra Shah, MD, Department of Refractive Surgery, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio