No financial interest for all authors Evaluation of the Intralase Femtosecond Laser Efficiency in LASIK Flap Creation Mounir A. Khalifa, MD Michael Rizman, MD. Waleed Allam, MD No financial interest for all authors
This study aimed at evaluation of the visual and refractive outcomes of wavefront-guided LASIK using the IntraLase femtosecond laser for flap creation. The study was conducted at Tufts University School of Medicine, Boston, Massachusetts, USA and included 117 eyes of 63 patients with myopia with or without astigmatism.
Preoperative statistical analysis Table 1: Patients’ age, preoperative refraction, and visual acuity data. Minimum Maximum Mean Std. Deviation Age 22 57 35.90 8.718 LogMAR UCVA 0.40 1.69 1.2503 0.31339 LogMAR BCVA 0.00 Manifest Sphere -8.25 -0.50 -3.9509 1.79206 Manifest Cylinder -2.00 -0.4081 0.45675 MRSE -8.500 -1.00 -4.15278 1.806218
Preoperative statistical analysis Table 2: Preoperative topography, pachymetry, and aberrations data. Minimum Maximum Mean Std. Deviation Mean K-Reading 40.15 48.40 43.9718 1.61819 Pachymetry 500 633 556.01 31.359 Total rms 0.14 0.81 0.3633 0.13198 Coma 0.02 0.50 0.1909 0.11748 Trefoil 0.00 0.1478 0.08391 Sph. aberrations -0.38 0.67 0.1338 0.16629
Intraoperative findings Achieved flap thickness and diameter: Table 3: Achieved flap thickness and diameter. Minimum Maximum Mean Std. Deviation Flap Thickness 91 144 116.48 12.215 Flap Diameter 8.7 9.1 8.956 0.1196
Intraoperative findings Pearson simple linear correlation coefficients: Table 4: Pearson correlation, flap thickness vs mean k-reading. Flap Thickness Mean K-Reading Pearson Correlation 1 0.017 Sig. (2-tailed) . *0.855 N 116 117 *P=0.855>0.05 No correlation between flap thickness and K-reading
Intraoperative findings Pearson simple linear correlation coefficients: Table 5: Pearson correlation, flap thickness vs pachymetry. Flap Thickness Pachymetry Pearson Correlation 1 -0.016 Sig. (2-tailed) . *0.866 N 116 117 *P=0.866>0.05 No correlation between flap thickness and preoperative corneal thickness
Intraoperative findings Pearson simple linear correlation coefficients: Table 6: Pearson correlation, flap diameter vs mean k-reading. Flap Diameter Mean K-Reading Pearson Correlation 1 -0.048 Sig. (2-tailed) . *0.610 N 116 117 *P=0.610>0.05 No correlation between flap diameter and K-reading
Intraoperative complications 7.8% intraoperative complication rate.
Early postoperative findings 114 eyes, out of 117, were available for postoperative follow-up. At the first postoperative day, the mean LogMAR UCVA was 0.03 ± 0.11 (mean around 20/22). At the first postoperative day, the peripheral host epithelium defects were noticed in 2 eyes (1.7%) and fine microstriae in one eye (0.9%). None of the eyes developed interface inflammation or diffuse lamellar keratitis (DLK). None of the eyes developed remarkable transient light sensitivity syndrome (TLSS).
Late visual and refractive outcomes safety Safety index (postop to preop BCVA) at 1,3, and 6 months = 1.1. Changes in BCVA in terms of Snellen’s lines. Table 7: Changes (gain or loss) in Snellen’s lines of BCVA. 1 Month 3 Months 6 Months 2 lines gain 0% 1% 1 line gain 36% 44% 52.1% Unchanged 62% 53% 44.8% 1 line loss 2% 2.1% 2 lines loss
Late visual and refractive outcomes (Efficacy) Efficacy index (postop UCVA to preop BCVA) at 1,3, and 6 months = 1.0. Time course of logMAR UCVA at 1,3, and 6 months.
Late visual and refractive outcomes Efficacy- Total rms # Sig. increase at 1 m. # Non-sig. increase at 3 m. # Back to the 1 m level at 6 m. Table 10: Total rms at 1, 3, and 6 months. Minimum Maximum Mean Std. Deviation Preop. rms 0.14 0.81 0.3633 0.13198 1 Month rms 0.12 0.90 0.5432 0.20781 3 Months rms 0.15 0.94 0.5804 0.22879 6 Months rms 0.86 0.5400 0.20185
Late visual and refractive outcomes Predictability- Attempted vs achieved correction at 6 m
Late visual and refractive outcomes Safety Visante OCT high resolution corneal scan obtained at 6 months postop.
Conclusions In this study, IntraLase was proved to be a safe, efficient, and a highly predictable means of LASIK flap creation. The IntraLase femtosecond laser has significantly reduced the incidence of LASIK flap complications. In addition to that reduction, IntraLase flap complications are much easier to manage than those of the mechanical microkeratome. Accordingly, IntraLase is becoming recognized as a safer method of flap creation. Its excellent efficacy and predictability with more predictable flap parameters make the IntraLase a very helpful tool in refractive surgery.
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