Mohamed Abdelrahman Awadalla,FRCS Magrabi Eye Hospital Cairo - Egypt Femtosecond Laser Versus Moria M2 Microkeratome in LASIK to Correct Myopia Mohamed Abdelrahman Awadalla,FRCS Magrabi Eye Hospital Cairo - Egypt

Introduction: Methods of flap creation have changed over the years from the evolution of the mechanical microkeratome to the introduction of the IntraLase femtosecond laser keratome, both of which have different mechanisms of action to create corneal resections. Some surgeon shifted to Femtosecond laser due to: - its safety as it avoids buttonholes and freecaps - flap cutting can be digitally programmed which lead to better predictability in flap thickness determination as in cases with thin corneas However Microkeratome users says that they are perfectly content with their results which are getting better with latest generation devices, not only they avoid buttonholes and freecaps but also they achieving small flap thickness standard deviation and furthermore Microkeratome purchase costs are much lower.

Patients and methods: Femtosecond laser assisted corneal flaps were performed in 56 eyes ( 26 patients ) Intralase flap setting: 9.0 mm diameter,120 um depth, 55 degree hinge & 65 degree side-cut angle. Mechanical microkeratome (Moria M2) flap were performed in 78 eyes ( 39 patients ) all were 130 um disposable Moria blades . All patient underwent customized laser ablation using VISX S4 customVue laser system. outcome assessment was based on refractive and visual outcome at 1 day, 1 and 3 months. Criteria: Myopic refraction up to – 7.00 D Sphere and – 1.50 D Astigmatism. Minimum age of 21 years old. Stable refraction within -/+ 0.50 D over the past year. Normal ophthalmic examination. Normal topography. No history of ophthalmic surgery. No history of autoimmune disease.

Patients and methods: Preoperative evaluation: UCVA, BCVA, manifest and cycloplejic refraction, slit lamp exam, fundus exam, applanation tonometry, pachymetry and corneal topography Postoperative evaluation: UCVA, BCVA, manifest and cycloplejic refraction, Aberrometry data for cylinder and high order aberration slit lamp exam, corneal topography and total ablation depth

Results: UCVA: UCVA of 20/20 was 73% in Intralase group and 62.7% in Microkeratome group in the 1st. Day, 88.4 % and 75.2% respectively at 7th day, 95.7% and 87.9% respectively after 1 month and 98.1% and 88.4% respectively after 3 months. i.e the mean acuities improved in both groups from 1 week to 3 months and the rates of changes wee similar in the 2 groups. The mean acuity were significantly better in the intralase group than the microkeratome at each interval. BCVA: More eyes in the intralase group than in the Microkeratome group were within -/+ 0.50 D of the intended manifest refraction at 1 week ( 93.67% and 74.2% respectively ) and 1 month ( 94% and 80% respectively ) At 3 months, the difference was not statistically significant ( 89% and 78.9% respectively ). Astigmatism: The astigmatism was within -/+ 0.50 D was in 98% in Intralase group and 80% in the Microkeratome group at 1 week, 96% and 88% respectively at 1 month and 98% and 88% respectively at 3 months interval i.e the mean astigmatism results were significantly better in the intralase group at all follow up visits. Aberrometry measurements : There were no significant difference in the preoperative aberrations between the two groups. At 3 month visit the Astigmatism and the Trefoil were significantly high in the microkeratome group otherwise the other aberration were almost the same between the 2 groups

Conclusions: Keratoectasia and flap efficiency remain a constant safety concern in laser in-situ keratomileusis surgery. Unexpectedly thick flaps as well as variable thickness continue to be a concern with safety in relation to microkeratome technology. Epithelial preservation, flap complications and newer issues such as Transient Light Sensitivity Syndrome are safety concerns of flap creation. Improved outcomes with regards to vision, induced astigmatism, induced higher-order aberrations and enhancement rates are seen to favor predictability of femtosecond technologies over the microkeratome. Recent biomechanical studies show improved healing with femtosecond laser flap creation compared with blade-assisted flap creation.

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