الفهرس 
Histopathological Changes in KeratoconusOnly 14 pages are availabe for public view
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Abstract
Keratoconus is a non inflammatory ectatic dystrophy characterized by progressive thinning, steepening, and apical protrusion of the cornea. These changes in corneal shape induce irregular astigmatism and myopic shift, causing gradual impairment of vision. In most cases, keratoconus occurs bilaterally, although the condition may be considerably more pronounced or appear considerably earlier in one eye of a given individual than in the other.
Keratoconus shows microscopic alterations in all corneal layers, but the earliest changes occurs in the superficial layers of the cornea.
There are many wayes for treatment and correction of keratokonus, but the right choice is depending on the stage of the disease.
There are two main types of intracorneal inserts manufactured by two medical device companies and marketed under the names Intacs and Ferrara rings. Both of them aims by there implantation to improve visual acuity without removing any corneal tissue or touching the central cornea with there advantages over other incisional, excisional or ablative refractive surgical techniques include faster and more predictable wound healing, a simpler surgical procedure, the ability to adjust refractive outcome (by using the appropriate thickness) and reversibility (explantation)
Two techniques of Intacs surgery for keratoconus have been reported an asymmetric technique in which a thicker segment is implanted inferiorly. This technique aims to treat the inferior steepening seen in most keratoconic corneas. The same thickness segment implantation technique aims to reduce the myopia and astigmatism by symmetrically flattening and supporting the central cornea. It seems that both techniques are effective in keratoconus.
In Ferrara ring selection, surgeons started to implant a pair of symmetrical segments in every case, but when the benefits of single segment or asymmetrical implantations were shown, alternative approaches proposed for Ferrara rings that took into account purely refractive data.