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Marine Gobbe, Dan Z Reinstein, Glenn Ian Carp, Louis Gobbe, Timothy J Archer; Optical Zone Centration Comparison between SMILE and LASIK. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3927.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the optical zone centration between myopic eyes treated with small incision lenticule extraction (SMILE) and myopic eyes treated with LASIK.
This was a retrospective analysis of 100 consecutive SMILE eyes of 100 patients and a matched group of 100 LASIK eyes of 100 patients. All SMILE treatments were performed using the VisuMax 500 kHz femtosecond laser and all LASIK treatments were performed with VisuMax and MEL 90 excimer laser. Both SMILE and LASIK treatments were centred on the coaxially sighted corneal light reflex. Inclusion criteria were preoperative spherical equivalent (SEQ) between<br /> -0.50 D and -10.00 D, CDVA 20/25 or better and 3 month Atlas topography data available. A difference map of the tangential curvature was generated for each eye using the pre-operative and 3 months post-operative maps. A grid and a set of concentric circles were superimposed on the difference map to locate the centre of the optical zone. The x and y co-ordinates of centration offset between the center of the optical zone and the corneal vertex were measured to the nearest 0.05 mm.
The mean centration offset was 0.20 ± 0.11 mm for the SMILE group and 0.18 ± 0.11 mm for the LASIK group, with no statistically significant difference between groups (p<0.01). In the SMILE group, the optical zone was centred within 0.1 mm of the corneal vertex in 17% of eyes, within 0.2mm in 55%, within 0.3 mm in 81%, and within 0.4 mm in 96% of eyes. In the LASIK group, the optical zone was centred within 0.1 mm of the corneal vertex in 24% of eyes, within 0.2 mm in 62%, within 0.3 mm in 92%, and within 0.4 mm in 98% of eyes. There was no systematic directional decentration in either group.
Although no eye tracker was used during the SMILE procedure, the optical zone was equally well centred compared with LASIK.
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