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Juan Curiel, Cristina Pacheco-Del-Valle, Oscar Baca, Alejandro Babayan, Regina Velasco; Is calculation of corneal tissue ablation depth determined by VISX Star S4 IR platform’s algorithm a reliable method?. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3128.
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© ARVO (1962-2015); The Authors (2016-present)
To compare predicted corneal tissue ablation depth and the obtained corneal tissue ablation depth in patients treated with laser in situ keratomileusis (LASIK).
Prospective, transversal and comparative self control trial. The predicted corneal tissue ablation was determined by entering the desired correction into the platform and using its algorithm (VISX Star S4 IR, VISX Inc., Santa Clara, CA). The corneal ultrasonic pachymetry (Accutome Accupach V 24-5000, Acutome Inc., Malvern, PA) was performed before surgery and one month after the same, in order to obtain the postsurgical corneal tissue ablation by subtraction. All surgeries were performed by different surgeons using the same microkeratome (M2 single use microkeratome, Moria Inc., Doylestown, PA). The corneal ultrasonic pachymetry was taken centrally by the same technician. Measurement was performed on each eye nine times and mean was reported.
Data from 26 patients (52 eyes) who underwent LASIK were available for the initial analysis. We analyzed a total of 19 patients (36 eyes). Seven patients were excluded because they did not come to follow-up visits and two eyes were excluded because of surgical complications. The mean age of the analyzed subjects was 25.89 years (range 20-42 years). The mean predicted corneal tissue ablation depth was 49.11 μm (standard deviation [SD], 19.60 μm) and the mean postsurgical corneal tissue ablation depth was 61.64 μm (SD, 28.07 μm). The mean preoperative spherical equivalent was -4.07 D (SD, 1.92 D) and the mean postoperative spherical equivalent was 0.18 D (SD, 0.73 D). We analyzed the variables under study with t test (p< 0.001).
The postsurgical corneal tissue ablation depth was greater than the predicted corneal tissue ablation depth determined by the platform used in this study, and it should be considered by refractive surgeons in patients with thin corneas in order to avoid residual beds of less than 300 μm.
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