Fast, powerful, precise and safe, the SCHWIND AMARIS represents an important advance in laser-assisted in situ keratomileusis (LASIK). It combines a high ablation speed with a turbo eye tracker for monitoring pupil and limbus tracking, rotational balance and advanced cyclotorsion control. These factors ensure the perfect balance between extremely high speed and accuracy. With its repetition rate of 500Hz, minimum spot size of 0.54mm (full width at half maximum, FWHM) and its super-Gaussian beam profile, the SCHWIND AMARIS ensures very high ablation accuracy; this results in exceptionally smooth treatment surfaces and an extremely accurate reproduction of ablation volumes, allowing successful treatment.
In our trial, all LASIK procedures were performed using the SCHWIND AMARIS, and all patients were corrected using the SCHWIND-CAM ‘aberration-free’ treatment. All evaluated eyes were healthy and untreated. All flaps were created using the Carriazo-Pendular microkeratome (superior hinge), and the optical zone was set to 6.0, 6.5 or 7mm. Pre-operatively, spherical equivalent refraction (SEQ) was -0.50 to -8.25D, the sphere was 0.00 to -8.25D and the cylinder was up to -5D. All data from the 364 eyes were analysed for a post-operative period of three months.
A scattergram is the best way to show the predictability of the refractive outcome. Figure 1 shows attempted refraction versus achieved refractive change for each eye three months post-operatively. The narrow scatter between laser settings and achieved SEQ at three months is obvious. The mean post-operative SEQ was -0.17±0.24D.
Figures 2a and 2b show the refractive outcome in terms of SEQ and defocus equivalent. An impressive 75% of the 364 evaluated eyes were in the range of ±0.25D of SEQ, and 89% were within ±0.5D in terms of defocus equivalent.
Change in Best Spectacle-corrected Visual Acuity – Safety
Safety is described by the change in best spectacle-corrected visual acuity (BSCVA), which is measured by the number of Snellen lines that change post-operatively. At three months, 44% of the evaluated eyes gained one or more Snellen lines, and no patient lost more than one Snellen line (see Figure 3).
Pre-operative Best Spectacle-corrected Visual Acuity versus Post-operative Uncorrected Visual Acuity
Figure 4 displays the pre-operative BSCVA compared with postoperative uncorrected visual acuity (UCVA) at three months. Fifty-five per cent of all treated eyes had a UCVA of 20/16 or better. In summary, a significant change towards improved visual acuity even for these early results is obvious.