Our eyes are probably our most precious sensory organs.
Im paired sight means impaired quality of life

The eyes are without doubt our most important sensory organs. To see properly, the light entering our eyes must produce a clear image on the retina. The optical system of the eye includes the cornea, the lens and the vitreous body. In a healthy eye, the incoming light is refracted in such a way that the focal point is such a way that the focal point is positioned exactly on the retina.

Normally the focal point is located at the central retinal fovea, creating optimal vision. However, irregularities in the optical system can lead to a shift of the focal point so that the clear image is produced in front of or behind the retina – preventing good sight. Such errors are referred to as refractive errors or visual defects, which are measured in diopters.

In the nearsighted eye, images focus IN FRONT of the retina, as the angle of incidence is too large. Objects in the distance appear blurry and indistinct.

In the farsighted eye, images focus BEHIND the retina, as the angle of incidence is too small. Objects that are near appear blurred.

Astigmatism can occur in conjunction with nearsightedness or farsightedness. Here, images focus on more than one point in front of, or behind the retina. The incoming light is thus focused on a line rather then a single point. The result is that all images, whether near or far, may be blurred.