A clouding or loss of transparency of the lens in the eye as a result of tissue breakdown and protein clumping.
Cornea is the outermost window of the eye. It being a transparent structure, allows light rays to get focused on the retina.
The retina is a thin layer of neural cells that lines the back of the eyeball of vertebrates and some cephalopods.
Refractive error, when left uncorrected is the most common cause of visual impairment.
Contact lenses are alternative to Eyeglasses which offer great relief to the people with refractive error defects.