Near-sightedness

• The medical term for being near-sighted is Myopia
• The term near-sighted is used simply because myopes are able to see close objects more clearly than distant objects
• The most common cause for myopia is an increase in axial length (front to back) of the eye during childhood and teenage years
• This results in images being focused in front of the retina
• Near-sightedness is easily correctable using "minus" lenses, thus a myopic person's prescription will always have a negative sign in front
  

Ex. If you consider a movie projector and screen. A myopic eye would be analogous to someone pulling the screen back so the image is out of focus.