Transcript Comparative analysis of LASIK flaps (Microkeratome Versus

Comparative Analysis of Lasik Flaps
(Microkeratome Versus Femtosecond laser )
• Lead Author: Dr.Santhosh Shivaji. MS.
Faculty: R Shetty FRCS, N.Raghu MS, K. B Shetty
MS , H K Matalia MS.
Authors have no financial interest.
Comparative Analysis of Lasik Flaps
(Microkeratome Versus Femtosecond laser )
• Purpose-
To compare visual outcomes, Flap
thickness, Contrast sensitivity and Corneal
biomechanics between fellow eyes randomized to
Lasik with the flap created by Mechanical
Microkeratome and the flap created by a
Femtosecond laser
Patients
• Sixty patients(120 eyes) underwent Lasik for myopia or
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myopic astigmatism
Sixty eyes - Microkeratome lasik
Sixty eyes- Femtosectond laser lasik.
Inclusion criteriaAge >21 yr and stable refraction for past 1 year ,
Refractive error range 2 – 7 Diopters and difference
between the fellow eye not exceeding 1D sphere and 0.5 D
cylinder.
Study Design -Randomized, controlled, paired-eye study
Methods:
• One eye of each patient was randomized to flap
creation with a 60 Hz Femtosecond laser (IntraLase
FS, IntraLase Corp., Irvine, CA) with intended
thickness of 100 microns and the fellow eye flap
created with a Mechanical Microkeratome (Moria
M2) with intended thickness of 100 microns.
• Patients were examined before and at 1, 3, and 6
months after Lasik.
Main Outcome Measures.
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Uncorrected visual acuity.
Best corrected visual acuity.
Contrast sensitivity.
Corneal biomechanics.
Flap thickness.
Patient preferences.
Visual acuity
Treatment Pre operative
1 month
3 month
6 month
Micro
kertatome
20/160
20/20
20/20
20/20
Femtosecond
laser
20/200
20/20
20/20
20/20
Flap Thickness
MICROKERATOME
Microns
Intended Flap
Thickness- 100 Microns
FEMTOSECOND LASER
Microns
112 ± 14.5
103.8 ± 8.6
[ 92- 121 ]
[ 96 – 110 ]
• Statistically significant difference between the intended
and achieved flap thickness seen in microkertome group.
• Flap thickness measured by – Anterior segment Optical
coherence tomography [ Tomey]
CORNEAL BIOMECHANICS
PRE –OP
CH
PRE- OP POST –OP POST –OP
CRF
CH
CRF
MICROKERATOME
9.7 ± 1.3 9.1 ±
1.4
9.0 ± 1.1 8.7 ± 1.3
FEMTOSECOND
LASER
9.9 ± 1.2 8.8 ± 1.3 8.9 ± 1.2 8.4 ± 1.2
No statistically significant differences in CH and CRF values
in both groups noted.
The corneal biomechanical properties were measured with
Ocular Response Analyzer (ORA).
CONTRAST SENSITIVITY
• No statistically significant differences in CS values at any
spatial frequency were found between groups before surgery
(>P0.01) measured by using the Functional Acuity Contrast
Test, optec 6500 digital .
Similar result found after surgery at low and medium spatial
frequencies (1.5, 3, 6, and 12 Cycles/degree).
However, a statistically significant improvement in CS for the
Femtosecond laser Lasik group was obtained at the high
spatial frequency (18 cycles/ degree; <P0.01).
PATIENT PREFRENCE
• At end of 6 months , 8 patients preferred the
vision in the eye that received Microkeratome
flap ,7 patients preferred the vision in the eye that
received the Femtosecond laser flap and rest of
all patients expressed no preference.
• Patients complained of redness for long duration
[ sub conjunctival haemorrhage ] in Femtosecond
laser group
Conclusion.
• The method of flap creation did not affect visual
outcomes, corneal biomechanics and contrast
sensitivity during the first 6 months after Lasik.
• The
Femtosecond
laser
created
highly
reproducible flaps that corresponded with the
preoperative intended thickness
• Patients did not perceive a difference in vision