REFRACTIVE ERRORS

The human eye behaves as a perfect optical system in a very small percentage of population. When the rays of light coming from a distant target, gets perfectly focused on the retina, the condition is called emmetropia.

MYOPIA OR SHORT SIGHTEDNESS

Refers to a state of the eye, wherein the rays of light coming from a distant target, get focused at a point in front of the retina. In this situation, minus powered glasses or contact lenses are necessary to focus this image onto the retina

HYPEROPIA OR LONG SIGHTEDNESS

Refers to a state of the eye, wherein the rays of light coming from a distant target, get focused at a point behind the retina. In this situation, plus powered glasses or contact lenses are necessary to focus this image onto the retina

ASTIGMATISM OR CYLINDRICAL POWER

Refers to a state of the eye, wherein the rays of light coming from a distant target, cannot focus at a single point on the retina. In this situation special lenses of different curvature are required to focus the light onto the retina