2. BASIC EYE ANATOMY

What is the lens?

• The lens is a clear part of the eye that helps to focus light, or an image, on the retina. 

• The retina is the light-sensitive tissue at the back of the eye.

• In a normal eye, light passes through the transparent lens to the retina.
 



photo from http://www.medicinenet.com/eye_diseases_pictures_slideshow/article.htm

   



from http://www.youtube.com/watch?v=JKwoMdiGNmY
and http://www.gifsoup.com/view1/1350565/eye3-o.gif




• Once it reaches the retina, light is changed into nerve signals that are sent to the brain.



• The lens must be clear for the retina to receive a sharp image.



from http://www.youtube.com/watch?v=JKwoMdiGNmY
and http://www.gifsoup.com/view2/1350580/electrical-signals-o.gif

 

 

• If the lens is cloudy from a cataract, the image you see will be blurred.