A: To see what we do now, the light bounces off the object you are looking at, into the pupil.  The light crosses your lens and the images gets focused.  The object you are looking at turns upside down.  The object you are looking at shines on the back of the eye.  The part is called the retina.  A retina contains two types of photoreceptors called rod cells and cone cells.  Rod and cone cells helps you to see colors and sharp details.  Then, the optic nerve carries the picture you see and your message goes to the brain.  What the brain does after the message goes to the brain is that it turns the picture the right side up.  The second thing the brain does is that it figures out what you are seeing and what you should do. Images are processed in the occiptal lobe of the brain.

A: We have two eyes because having two eyes increases your angle of vision.  It helps you to judge depth.  Having two eyes allows us to see 180 degrees and three-dimensional objects.

A: When people grow older, their lens loses its elasticity. The flattened shape and the viewing of the near objects get difficult when distance objects are still clear. This condition is called presbyopia (or farsightedness). You can use corrective glasses. They bring near objects to focus. There is another type of farsightedness called hypermetropia. Hypermetropia can be caused by having an eye ball that is shorter than normal. People with myopia (or nearsightedness) have eye balls that are longer than normal. A nearsighted person has difficulty seeing distant objects but can read books easily. Nearsightedness is caused by the stress of working for a long period of close work. Nearsightedness usually begins when you are a kid. When you have nearsightedness or farsightedness, there is a way to cure you. Most older people wear contact lens to make them see better. You can use glasses when you are younger. For contact lens or glasses, there are certain types. For correcting nearsightedness, you use concave lens and for farsighted people, they use convex lens.

A: Color blindness is one of the diseases some humans have. Color blindness is when they can't really notice the colors red, green, blue-violet, and other combinations. Color blindness is always an inherited disorder caused by genetic defect on X Chromosome. Color blindness mostly occurs primarily in males. Most males have color blindness because they have one X Chromosome and females have two X Chromosome.

A: Other disorders/diseases we have with sight are cataracts, astigmatism, and blindness. Cataracts are a disorder that gradually develops in your lens of your eye. It gets cloudy or darkened. Cataracts develop by change in the chemical composition of the lens. Cataracts are most often found around people over the age of 55. Astigmatism is a vision that occurs at the front surface of your eye (the cornea). It is not irregular shape when your eye is focusing properly on the back of your eye. Astigmatism could occur at all ages. Blindness is a disorder that people of all ages suffer from. Usually, it is caused by either improper birth or an injury. When you are blind, it may be caused by a blockage of light or by a disease of the optic nerve.

<BACK> to the index