What causes
shortsightedness or myopia?
Symptom: A person with shortsightedness cannot see objects which
are far away but can see objects which are nearby.
Reason for the defect: The light rays from the object move through the eye and
get converged before the retina. As image of the object is not formed on the
retina we cannot see the object.
Causes for the defect: The lens is too
convex or too curved is one of the reason for this defect. Another reason for
this defect is the eye ball may become lengthened from front to back.
How to rectify this defect?
A spectacle with concave lens has
to be used for rectifying this defect. Concave lens is a diverging lens which makes
the light rays to travel further and make them to meet on the retina. The power
of the lens has to be noted with a negative sign. Shortsightedness or myopia is
mainly caused in school going children.
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