Refractive Errors
In order to see clearly, light rays must be bent or "refracted" to focus on the retina, in the back of the eye. Along the retina, the rods and cones sense the light, and create impulses, that travel to the brain and are interpreted as images. When you have a "refractive error", the shape of your eye doesn't properly refract the light so the image is blurred rather than clear.
Myopia, hyperopia, astigmatism, and presbyopia are refractive errors that lead to blurred vision.
| NEARSIGHTEDNESS - MYOPIA |
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Normally, light passes through the cornea and lens, focusing on the retina. In the near sighted eye, the eye is longer, thus the light is focused in front of the retina, resulting in poor distance vision.
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| FARSIGHTEDNESS - HYPEROPIA |
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| Normally, light passes through the cornea and lens, focusing on the retina. In the far sighted eye, the eye is shorter, thus the light is focused behind the retina, resulting in poor near vision, and in some cases, distance vision. |
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| ASTIGMATISM |
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| The normal cornea is curved equally in all directions. With astigmatism the cornea is irregularly shaped, like a spoon's back. Light rays have numerous focal points and focus on different areas of the retina, instead of one point, causing "ghost like" double images. |
PRESBYOPIA
The lens of a young person is soft and flexible, easily changing shape to focus on near or distant objects. As we age, the lens becomes harder and less flexible, making it difficult to focus on near objects. This condition is normal and usually occurs near the age of 40. |
