what is MYOPIA

Myopia or short-sightedness is a type of refractive
error in which parallel rays of light coming from infinity
are focused in front of the retina when
accommodation is at rest .

Refraction in a myopic eye.

Etiological classification
1. Axial myopia results from increase in anteroposterior
length of the eyeball. It is the
commonest form.
2. Curvatural myopia occurs due to increased
curvature of the cornea, lens or both.
3. Positional myopia is produced by anterior
placement of crystalline lens in the eye.
4. Index myopia results from increase in the refractive
index of crystalline lens associated with nuclear
sclerosis.
5. Myopia due to excessive accommodation occurs
in patients with spasm of accommodation.