MYOPIA
It is a common condtion in which light rays converge in front of retina and a diverging or concave lens is required to focus light rays over retina. These lenses in refraction box appear red. The first diagram below shows how light is converging before retina and second diagram showing that a diverging lens is causing rays of light to focus on retina
HIGH MYOPIA
Myopia more than -6 diopters is called high myopia.
Risk factors of myopia
esophoria, against-the-rule astigmatism, premature birth, family history, and intensive near work
Prevention of myopia
0.01% atropine eye drops because it inhibits accomodation
use of glasses
out door activity
DEGENERATIVE OR PATHOLOGICAL MYOPIA
It is a sever form of myopia in which there is damage to retina.
TREAMTENT
A convcave lens is used to treat myopia. In children under the age of 2 year, myopia more than -5 diopters should be corrected. And between 2 to 4 year upto -3 diopters. should be corrected. In older children even low degree of myopia should be corrected. In case of squint however full correction is given deducting only working distance.