الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The transparent cornea forms the anterior portion of the outer casing of the eye. It has the dual function of protecting the inner contents of the eye as well as providing about two thirds of eye’s refractive power. The major load-bearing component of the cornea is the stroma. The collagen in the stroma is laid down within lamellae. The organization and interaction between fibrils within different lamellae is dependent on the distance from Bowman’s layer. Collagen fibrils that form the anterior stroma are more interweaving with one another significantly more than in the posterior stroma, this interweaving result in denser collagen distribution anteriorly with relatively stiffer mechanical properties.
In recent years, the interest in corneal biomechanics has significantly increased due to increasing clinical utility in understanding the structural and material properties of the cornea. Corneal biomechanics has the potential to be used for screening and planning for refractive surgeries, and as a possible indicator of disease risk.
A new procedure called small incision lenticule extraction (SMILE) was developed using femtosecond laser. It has advantages over microkeratome-LASIK that include less flap-related complications, the ability to be performed in thinner corneas and/or in higher refractive errors, increased biomechanical integrity, and lesser degree of dry eye.
This study was conducted on 60 eyes of normal healthy people seeking refractive surgery, divided into two groups. group I, included 30 eyes that had SMILE operation, and group II included 30 eyes that had LASIK operation.