Table 2.

Classification of myopia based on different entities

Classification	Cause
Based on clinical entity
Basic (simple) myopia	-- (<6 D) hinge on axial length, optical power of the cornea, and crystalline lens of the eye[56,57]
Nocturnal myopia	-- Low illumination of light and darkness are responsible[58]
Pseudo-myopia	-- Due to ciliary muscle spasm or unrelaxed accommodation system
Pathological myopia	-- Associated with degenerative changes at the posterior pole and retinal periphery
Induced myopia	-- Occurs by some external pharmaceutical agents or by disease conditions. It is reversible.[57]
Based on age
Congenital myopia	--At birth to whole life
Youth onset myopia	--From 5 to 20 years
Early adult-onset myopia	--From 20 to 40 years
Late adult-onset myopia	--After 40 years
Based on degree
Low myopia	<−3 D
Medium myopia	−3 to <−6 D
High myopia	>−6 D