Refractive surgery?

Introduction
Laser refractive surgery is becoming increasingly popular as people are turning to alternatives to traditional spectacles and contact lenses for vision correction. 120 000 surgeries were performed in France in 2008. About 9 million procedures have been performed in the United States since the approval of the excimer laser for refractive surgery in late 1995. About 1.4 million procedures were performed in 2007 alone (Marketscope).

Anatomy of the cornea
The transparent cornea is about one-half millimeter thick and has five distinct layers. The epithelium is the most exterior layer providing the smooth refractive surface and barrier against infection. The function of Bowman's membrane, which lies beneath the epithelium and its basement membrane, is unclear.
The stroma, made up of intertwining lamellae of collagen fibrils, provides structure and accounts for 90 percent of the corneal thickness. The endothelium and its basement membrane (Descemet's membrane) form the innermost layers. Endothelial cells,  are responsible for the natural corneal dehydration necessary for corneal clarity. Average central corneal thickness is about 550 µm, increasing to about 700 µm in the periphery. The cornea has a diameter (from the front surface) of about 11 mm vertically and 12 mm horizontally. The air-tear interface is the first refractive surface that light encounters and accounts for about 80% of the eye's total refractive power; the average corneal curvature (K readings) in the adult cornea is approximately 44.00 diopters (D).

Three types of cells are present in the epithelium: (1) basal columnar cells attached to the epithelial basement membrane via hemidesmosomes, (2) wing cells noted for thin winglike projections, and (3) surface cells joined by connecting bridges and covered by microvilli. Mucin is attached strongly to the surface. Usually, 5-7 layers of cells are present. Unlike stratified squamous epithelium in other areas of the body, the epithelium in the eye has an exceptionally smooth and regular surface, contributing to the transparency and light transmission characteristics of the cornea.

The Bowman layer is not a membrane, but rather an acellular structure consisting of collagen and representing the most superficial layer of the stroma.

The stroma makes up about 90% of the corneal thickness and consists of regularly arrayed flattened bundles of collagen called lamellae. Approximately 200-250 lamellae are present in the human cornea. Each bundle extends the width of the cornea and is about 2 µm thick and up to 260 µm wide. The parallel arrangement of these bundles together with the uniform spacing between collagen fibrils helps explain corneal transparency. Although relatively acellular, stromal fibroblasts called keratocytes can be found scattered throughout the stroma between lamellae, and they are responsible for collagen production and wound healing.