الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Keratoconus (KC) is a fairly common bilateral,
noninflammatory, degenerative axial ectatic condition of the cornea in
which the cornea assumes an irregular conical shape. This results in
progressive myopia and irregular astigmatism with associated
progressive loss of vision and thus reduced quality of life.
Keratoconus was initially broadly defined based on the shape
and location of the cone. These include round or nipple cones with a
central conical protrusion, and oval cones, often with inferior sagging.
It is the most common primary corneal ectasia with an annual
estimated incidence of 2 in 100,000 and a prevalence of 54.5 in
100,000 in the general population.
It typically commences at puberty and progresses to the third or
fourth decade of life at which time progression slows and often stops.
It may occur in one eye initially but commonly affects both eyes, with
one eye being more severely affected than the other. Both sexes are
equally affected.
The goals of management of keratoconus are to prevent
progression of ectasia, improve refractive error and aberrations,
correct ectasia, and restore the normal prolate shape of the cornea.
Keratoconus management varies depending on the disease severity.
Soft lenses or soft toric contact lenses may be adequate early in
the disease to correct both myopia and regular astigmatism. As the
disease progresses, rigid gas-permeable (RGP) lenses or various
specialized lenses, may be required.
Intrastromal Corneal Rings Segments (ICRS) implantation
surgery is one of the alternate options for regularization of the cornea.
It aims to induce a geometric change in the central corneal curvature,
thus, reducing the refractive error and flattening of the cornea, and
tends to preserve corneal asphericity without removing tissue or
contact with the cornea center. When the advanced stage is reached,
the only treatment option is corneal transplantation.