It is hypothesized that lens stem cells lie inside the equatorial capsule o
f the lens. The lens fiber cells and anterior capsule epithelium are derive
d from the lens stem cells, which are susceptible to damage by many environ
mental and endogenous factors and become functionally abnormal. Abnormality
of the lens stem cells leads to opacification of the lens fiber cells and
to a reduced number of anterior capsule epithelia.