Evaluation of the Intralase Femtosecond Laser Efficiency in LASIK Flap Creation

1
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

2

• 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.

3
Preoperative statistical analysis
Table 1 Patients age, preoperative refraction, and visual acuity data. Table 1 Patients age, preoperative refraction, and visual acuity data. Table 1 Patients age, preoperative refraction, and visual acuity data. Table 1 Patients age, preoperative refraction, and visual acuity data. 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 0.00 0.00 0.00
Manifest Sphere -8.25 -0.50 -3.9509 1.79206
Manifest Cylinder -2.00 0.00 -0.4081 0.45675
MRSE -8.500 -1.00 -4.15278 1.806218
4
Preoperative statistical analysis
Table 2 Preoperative topography, pachymetry, and aberrations data. Table 2 Preoperative topography, pachymetry, and aberrations data. Table 2 Preoperative topography, pachymetry, and aberrations data. Table 2 Preoperative topography, pachymetry, and aberrations data. 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 0.50 0.1478 0.08391
Sph. aberrations -0.38 0.67 0.1338 0.16629
5
Intraoperative findings

• Achieved flap thickness and diameter

Table 3 Achieved flap thickness and diameter. Table 3 Achieved flap thickness and diameter. Table 3 Achieved flap thickness and diameter. Table 3 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
6
Intraoperative findings

• Pearson simple linear correlation coefficients

Table 4 Pearson correlation, flap thickness vs mean k-reading. Table 4 Pearson correlation, flap thickness vs mean k-reading. Table 4 Pearson correlation, flap thickness vs mean k-reading. Table 4 Pearson correlation, flap thickness vs mean k-reading.
Flap Thickness Mean K-Reading
Flap Thickness Pearson Correlation 1 0.017
Flap Thickness Sig. (2-tailed) . 0.855
Flap Thickness N 116 116
Mean K-Reading Pearson Correlation 0.017 1
Mean K-Reading Sig. (2-tailed) 0.855 .
Mean K-Reading N 116 117
P0.855gt0.05
No correlation between flap thickness and
K-reading
7
Intraoperative findings

• Pearson simple linear correlation coefficients

Table 5 Pearson correlation, flap thickness vs pachymetry. Table 5 Pearson correlation, flap thickness vs pachymetry. Table 5 Pearson correlation, flap thickness vs pachymetry. Table 5 Pearson correlation, flap thickness vs pachymetry.
Flap Thickness Pachymetry
Flap Thickness Pearson Correlation 1 -0.016
Flap Thickness Sig. (2-tailed) . 0.866
Flap Thickness N 116 116
Pachymetry Pearson Correlation -0.016 1
Pachymetry Sig. (2-tailed) 0.866 .
Pachymetry N 116 117
P0.866gt0.05
No correlation between flap thickness and
preoperative corneal thickness
8
Intraoperative findings

• Pearson simple linear correlation coefficients

Table 6 Pearson correlation, flap diameter vs mean k-reading. Table 6 Pearson correlation, flap diameter vs mean k-reading. Table 6 Pearson correlation, flap diameter vs mean k-reading. Table 6 Pearson correlation, flap diameter vs mean k-reading.
Flap Diameter Mean K-Reading
Flap Diameter Pearson Correlation 1 -0.048
Flap Diameter Sig. (2-tailed) . 0.610
Flap Diameter N 116 116
Mean K-Reading Pearson Correlation -0.048 1
Mean K-Reading Sig. (2-tailed) 0.610 .
Mean K-Reading N 116 117
P0.610gt0.05
No correlation between flap diameter and K-reading
9
Intraoperative complications
7.8 intraoperative complication rate.
10
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).

11
Late visual and refractive outcomes safetySafety
index (postop to preop BCVA) at 1,3, and 6 months
1.1.
Changes in BCVA in terms of Snellens lines.
Table 7 Changes (gain or loss) in Snellens lines of BCVA. Table 7 Changes (gain or loss) in Snellens lines of BCVA. Table 7 Changes (gain or loss) in Snellens lines of BCVA. Table 7 Changes (gain or loss) in Snellens lines of BCVA.
1 Month 3 Months 6 Months
2 lines gain 0 1 1
1 line gain 36 44 52.1
Unchanged 62 53 44.8
1 line loss 2 2 2.1
2 lines loss 0 0 0
12
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.
13
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. Table 10 Total rms at 1, 3, and 6 months. Table 10 Total rms at 1, 3, and 6 months. Table 10 Total rms at 1, 3, and 6 months. 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 0.14 0.86 0.5400 0.20185
14
Late visual and refractive outcomes Efficacy-
Total coma
Sig. increase at 1 m. Non-sig. decrease at 3
m. Non-sig. decrease at 6 m.
Table 11 Total coma at 1, 3, and 6 months. Table 11 Total coma at 1, 3, and 6 months. Table 11 Total coma at 1, 3, and 6 months. Table 11 Total coma at 1, 3, and 6 months. Table 11 Total coma at 1, 3, and 6 months.
Minimum Maximum Mean Std. Deviation
Preop. Coma 0.02 0.50 0.1909 0.11748
1 Month Coma 0.04 0.77 0.2951 0.14921
3 Months Coma 0.03 0.77 0.2930 0.17042
6 Months Coma 0.02 0.62 0.2619 0.14336
15
Late visual and refractive outcomes Efficacy-
Spherical aberrations
Sig. increase at 1 m. Sig. increase at 3 m.
Non-sig. decrease at 6 m.
Table 12 Total spherical aberrations at 1, 3, and 6 months. Table 12 Total spherical aberrations at 1, 3, and 6 months. Table 12 Total spherical aberrations at 1, 3, and 6 months. Table 12 Total spherical aberrations at 1, 3, and 6 months. Table 12 Total spherical aberrations at 1, 3, and 6 months.
Minimum Maximum Mean Std. Deviation
Preop. Sph. Ab. -0.38 0.67 0.1338 0.16629
1 Month Sph. Ab. -0.07 0.76 0.2923 0.23636
3 Months Sph. Ab. -0.11 0.86 0.3619 0.27036
6 Months Sph. Ab. 0.01 0.74 0.3208 0.22626
16
Late visual and refractive outcomes Efficacy-
Trefoil
Non-sig. fluctuations.
Table 13 Trefoil at 1, 3, and 6 months. Table 13 Trefoil at 1, 3, and 6 months. Table 13 Trefoil at 1, 3, and 6 months. Table 13 Trefoil at 1, 3, and 6 months. Table 13 Trefoil at 1, 3, and 6 months.
Minimum Maximum Mean Std. Deviation
Preop. Trefoil 0.00 0.50 0.1478 0.08391
1 Month Trefoil 0.01 0.37 0.1502 0.09312
3 Months Trefoil 0.01 0.39 0.1462 0.08045
6 Months Trefoil 0.04 0.38 0.1623 0.08175
17
Late visual and refractive outcomes Efficacy-
Contrast sensitivity
Increased contrast at all frequencies at all
postoperative visits. Significant only at high
spatial frequencies of 12 and 18 cpd.
18
Late visual and refractive outcomes
Predictability- MRSE
MRSE within 0.5 and 1 D at 1,3, and 6 months.
19
Late visual and refractive outcomes
Predictability- Attempted vs achieved correction
at 6 m
20
Late visual and refractive outcomes Safety

• Visante OCT high resolution corneal scan obtained
  at 6 months postop.

21
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.

22
THANK YOU