Wavefront-guided LASIK Systems: A New Frontier
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Wavefront laser technology is constantly evolving and is used by ophthalmologists to improve the quality of vision in patients with nearsightedness, farsightedness and astigmatism. As this technology evolves, it is important that ophthalmologists stay abreast of developments and assess the differences among the available platforms.
Clinical comparison study
Shady T. Awwad, MD, and colleagues1 performed a clinical study designed to evaluate and compare the visual and clinical outcomes of wavefront-guided procedures such as CustomCornea (Alcon Laboratories Inc, Fort Worth, Texas) and CustomVue (Visx, Santa Clara, Calif.). In this study, 93 consecutive eyes from 56 patients with myopic astigmatism underwent wavefront-guided LASIK. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and manifest refractive spherical equivalent (MRSE) were measured preoperatively and at 1 day, 1 week, 1 month and 3 months postoperatively. An early treatment diabetic retinopathy study (ETDRS) chart was also used to determine visual acuity. Contrast sensitivity was measured preoperatively and at 1 month and 3 months and wavefront mapping postoperatively and at 3 months.
Manifest refraction that met the Food and Drug Administration label for both CustomCornea and CustomVue was an inclusion criterion used in this study. It is also important to note that no physician adjustment was used for the CustomCornea system, whereas a -0.2 D adjustment value was used for the CustomVue by all surgeons.
Postoperative results
Preoperatively, the CustomCornea group had a mean sphere of -3.9 D ±1.62 D (range -0.5 D to -7.25 D), mean cylinder of 0.62 D ±0.39 D (range 0 D to 1.5 D), and mean MRSE of -3.59 ±1.54 D. The CustomVue group had a sphere of -3.87 D ±1.45 D (range -1.75 D to -6.75 D), cylinder of 0.49 ±0.36 D (range 0 D to 1.5 D), a MRSE of -3.62 D ±0.36 D. At 3 months, 98% of the CustomCornea group and 95% of the CustomVue group were within 0.5 D of intended correction. Ninety-nine percent of eyes did not change >0.5 D (MRSE) between 1 month and 3 months. CustomCornea eyes improved on contrast sensitivity testing and had higher percentages of 20/15 Snellen and 20/12 by ETDRS acuity testing than CustomVue. Both laser groups had a decrease in overall higher-order aberrations with statistical significance being exhibited in the CustomCornea group only for coma and spherical aberration.
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Conclusion
In conclusion, it is evident that both wavefront-guided laser platforms are effective, predictable and safe and deliver excellent refractive stability. Both are superior to the previously published results for conventional LASIK and require fewer retreatments. CustomCornea was shown to provide better quality of vision for the following reasons: based on the study data, treatments with CustomCornea increased patients’ chances of seeing 20/15 or better (Figure 1); improved contrast sensitivity, especially under dim light conditions with glare (Figure 2); and significantly decreased higher-order aberrations (e.g., coma and spherical aberrations) (Figure 3).
The future of wavefront-guided LASIK
It is important to note that not all laser platforms are alike and that they should be judged individually. Physicians’ acceptance and patients’ satisfaction and demand have resulted in CustomCornea becoming the treatment of choice, despite premium pricing for the procedure.
Reference
- Awwad ST, El-Kateb M, Bowman RW, Cavanagh HD, McCulley JM. Wavefront-guided Laser in situ Keratomileusis with the Alcon CustomCornea and the VISX CustomVue: Three-month results. J Refract Surg. 2004;20(5):S606.