2. Definition
• Keratoconus is a clinical term used to describe
a condition in which the cornea assumes a
conical shape because of thinning &
protrusion
3. Introduction
• characterized by progressive corneal
steepening, most typically inferior to the
center of the cornea
• eventual corneal thinning, induced myopia,
and both regular and irregular astigmatism.
4. • Approx 50% of normal fellow eyes will
progress to KC within 16 years.
• Both eyes are affected eventually, at least on
topographical imaging, in almost all cases.
5. Etiopathogenesis
• not fully understood
• both genetic and environmental processes are
likely to be involved.
• Keratoconus is probably not a single disorder,
but rather a phenotypic expression of several
possible causes.
6. • A hallmark of keratoconus is stromal thinning,
related to alterations in enzyme levels in the
cornea, causing stromal degradation.
• Increased levels of degradative lysosomal
enzymes and decreased levels of inhibitors of
proteolytic enzymes in corneal epithelium.
• consistent with the observation of increased
collagenolytic and gelatinolytic activity in
keratoconic cells.
7. • Loss of stromal keratocytes has also been
reported in keratoconus, as suggested by
confocal microscopy.
• investigators have suggested that
abnormalities in corneal collagen and its
cross-linking may be the cause of keratoconus.
8. • Eye rubbing is strongly associated with the
development of Keratoconus, may be related
to mechanical epithelial trauma, triggering a
wound-healing response that leads to
keratocyte apoptosis
• cytokine interleukin-1 has been suggested as a
mediator of eye rubbing and stromal
degradation.
9. • Most patients do not have a family history,
with only about 10% of offspring developing
KC
• Autosomal dominant transmission with
incomplete penetrance has been proposed.
