Comparison of Wavelight Allegretto Eye-Q and Schwind Amaris 750S excimer laser in treatment of high astigmatism

Abstract

Purpose To compare functional outcomes of Wavelight Allegretto Eye-Q 400Hz and Schwind Amaris 750S excimer laser for astigmatism between 2 and 7 diopters(D). Methods Prospective comparative non-randomized case series of 480 eyes assigned in two laser groups and further divided into myopic and mixed astigmatism subgroups. All treatments were centered on corneal vertex. One-year results were compared between the groups. Statistical analysis was performed using z-test. Results Both Allegretto and Amaris postoperative uncorrected distance visual acuity (UDVA) improved in comparison to preoperative corrected distance visual acuity (CDVA). The difference was significant in the Allegretto group for myopic astigmatism (p=0.017). There was no difference in postoperative UDVA between lasers. Average sphere decreased in all groups for both lasers (p<0.001) without difference in effectiveness of spherical correction between lasers for both groups. In Allegretto, average cylinder decreased from −3.30D to −0.55D in myopic astigmatism (p<0.001) and from −3.84D to −0.85D in mixed astigmatism (p<0.001). In Amaris average cylinder decreased from −3.21D to −0.43D in myopic astigmatism (p<0.001) and from −3.66D to −0.58D in mixed astigmatism (p<0.001). Amaris group had less residual astigmatism (myopic astigmatism p= 0.023, mixed astigmatism p<0.001). Mean spherical aberration shifted from positive to negative in mixed astigmatism for both lasers. Conclusion Both lasers are effective in terms of UDVA, CDVA, spherical correction, and preservation of high-order aberrations. However, Amaris was more effective in cylinder correction.

Topography-Guided Transepithelial Surface Ablation in the Treatment of Moderate to High Astigmatism

“…Data from a review of recent studies of corneal laser refractive surgery for moderate to high astigmatism are given in Table E (available in the online version of this article). [4][5][6][8][9][10][11][12][13][14][15][16] Across these studies, the percentage of eyes achieving postoperative residual cylinder of 1.00 D or less after treatment for myopic astigmatism ranged from 39.6% to 95.7%, compared with 97.4% in our series. The percentage of eyes achieving a postopera- Topography-Guided Transepithelial Surface Ablation/Chen et al tive spherical equivalent within 1.00 D of the intended correction ranged from 86% to 99.2% compared with 99.3% in this study.…”

“…Hyperopic and mixed astigmatism are technically demanding and difficult to correct. 13,14 We observed a slight undercorrection of astigmatism in both of our groups, but this was more evident in the mixed astigmatism group. Data indicating undercorrection of 4% (myopic astigmatism) and 19% (mixed astigmatism) are corroborated by negative mean magnitudes of error of -0.08 and -0.34 D, and arithmetic mean DVs of 0.38 and 0.65 D for the myopic and mixed astigmatism groups, respectively.…”

“…[24][25][26] Good control of spherical aberration and a physiological postoperative corneal shape may be achieved with aspheric laser ablation profile design. 14 The ablation procedure used in this series minimizes the induction of spherical aberration by adjusting the target value for asphericity according to the preoperative anterior corneal curvature and the planned curvature change, as well as by compensating for the reduction in radial efficiency of the laser toward the corneal periphery. We did not observe an increase in coma-like HOAs in our study and this may also be attributed to the ablation design, which is based on the existing centering and symmetry of the corneal optics measured by topography.…”

Comparison of femtosecond and excimer laser platforms available for corneal refractive surgery

“…Although they have individually been shown to be safe and effective, there are few comparative studies with other laser platforms [66,67 && ]. Bohac et al [68] prospectively compared outcomes of wavefront-optimized myopic LASIK with the Amaris and the Allegretto and found that the Amaris was more effective in cylinder correction. However, a subsequent vector analysis of astigmatic outcomes by the same group did not reveal any significant difference between platforms [69 & ].…”

High-speed photorefractive keratectomy with femtosecond ultraviolet pulses

“…Excimer laser-based systems evolved from high energy, low repetition rate lasers that covered a large area of the cornea in a single shot into ∼1000 Hz repetition rate flying spot machines with sophisticated scanning patterns and fast eye tracking systems. [6][7][8][9] Most practical disadvantages of the excimer lasers (intense maintenance required, toxic gases used as gain medium, relatively low stability of output, poor beam quality) have been successfully overcome or at least became manageable by the use of sophisticated engineering solutions and application protocols. 10,11 The clinical outcomes of UV systems for corneal ablation based upon nanosecond solid-state lasers with harmonic generators 12,13 have been demonstrated to be equivalent to those of excimer lasers.…”