Your Vision
Understanding the essentials at first glance
Our eyes are our most important sensory organs. The more clearly we see, the more life has to offer. Visual clarity depends upon how optical impressions are perceived by the retina, the inner surface of the back of the eye.
How does that work?
The cornea, the lens, and the vitreous body bend light rays entering the eye to focus them on a particular point on the retina. When this focal point occurs either in front of or behind the retina, the result is unclear vision. Eye doctors measure this defect in units called diopters.
Nearsightedness
In a nearsighted eye, either the cornea is too steep or the eyeball is too long, causing incoming rays of light to focus the image in front of, rather than on, the retina.
As a result, near objects are perceived clearly, but distant objects appear blurred and out of focus.
Farsightedness
In a farsighted eye, either the cornea has a weak curve or the eyeball is too short, causing incoming rays of light to focus the image behind, rather than on, the retina.
As a result, distant objects are perceived clearly, but near objects appear blurred and out of focus.
Astigmatism
In an astigmatic eye, the cornea has an uneven curvature. Instead of converging at one focal point, light rays merge in a line in front of or behind the retina. Astigmatism can occur in combination with nearsightedness and farsightedness.
As a result, the perception of objects is blurred and distorted.
