Myopia is the refractive abnormality, during which a parallel beam of rays enters the eye that is not focused in retina, but in front of it, and as a result the idol of an object is not portrayed clearly on retina.
Astigmatism mainly originates from the corneous tunic. When the curvature of cornea is not uniformed with its various meridians, then the object’s focus it is not possible to find itself on the retina.
Hyperopia is the refractive abnormality in which luminous rays are focused behind the retina, when the eye is calm.
Photophobia it is a symptom that most times has an idiopathick character. The basic Characteristic of selfimmuned eye diseases is that the eye or even parts of it,are attacked by white corpuscles of the organism itself.
Cataract is the clouding of the lens inside the eye, which leads in a decrease in vision. All people after a certain age show signs of cataract.