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M. Doat, B. Amari, J.-L. Bourges, N. Rocher, G. Renard, J.-M. Legeais; Comparison of Visx Customvue Theoretical Values of Corneal Photoablation to Postoperative Values Measured With Oct Visante and Pentacam in Lasik for Myopia. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5654.
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© ARVO (1962-2015); The Authors (2016-present)
Analyze and compare the values of theoretical corneal photoablation to the real values measured postoperatively using OCT Visante (Ziess) and Pentacam (Oculus) after wavefront-guided LASIK.
This analysis included 60 eyes of 30 patients who had wavefront-guided LASIK using femtosecond IntraLase laser (AMO) (corneal flap: 120 µm) and excimer VisX Star 4 IR (AMO) for myopia. At 1 month postoperatively, inclusion criteria were uncorrected visual acuity 20/20 and ± 0.50 D sphere. Corneal pachymetry were measured with OCT visante and Pentacam preoperatively and at 1 month postoperatively. Central corneal ablation was calculated by making the subtraction of pachymetry preop and postop. We compared these values to the theoretical values planned by the CustomVue profile of ablation. Furthermore we measured the corneal flap thickness and the stromal posterior bed thickness using the OCT Visante and we compared them to the theoretical expected values.
In preoperative, mean value of CustomVue theoretical corneal photoablation was 76µm ±14µm. Mean value of corneal thinning obtained in OCT Visante was 68µm ± 11µm. The mean value of corneal thinning obtained in Pentacam was 72µm ± 20µm. The difference was significant ( p=0.03 ) between CustomVue and OCT but not significant ( p=0.45 ) between CustomVue and Pentacam. The average of thickness of the corneal flap was 123.6µm ± 1.8µm. Mean theoretical value calculated for posterior stromal bed was 350µm ± 35µm. Mean value of the posterior stromal bed measured using OCT Visante was 354µm ± 39µm. The difference were not significant ( p=0.17 ).
Theoritical CustomVue values of corneal photoablation were predictable. Values observed after Lasik measured by Pentacam and OCT were lower than the theoretical values. One of the possible reasons of this difference was a secondary epithelial hyperplasia in the central corneal flattening.
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