HOW DOES ASTIGMATISM AFFFECT SIGHT?
To fully understand why astigmatism causes a disturbance in sight, it is helpful to understand the process of sight. The crystal clear cornea is situated at the very front surface of the eye and enables light to enter the eyeball. At that point of entry, the cornea accomplishes about four-fifths of the refractive work needed for clear vision, bending light rays toward one another into a point. The lens further refines the refractive work begun by the cornea and directs that point of light towards a precise location on the retina (the fovea). If light is not focused into that fine point, the image that reaches the retina cannot be clearly transmitted to the brain. When astigmatism is present, the surface of the cornea, instead of being spherical, is distorted. Therefore, light rays entering the eye are not focused into the fine point needed for clear vision. Rather, light is focused on two distinct points, neither of which may be on the retina, resulting in a blurred image.
