2.87 - Focusing

2.87 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity


- Most of the bending of the light rays is done by the curved cornea, but your lens can bend the light rays slightly. 
- The shape of the lens is controlled by the ciliary muscles. 


If you are looking at a distant object: 
- The ciliary muscles relax
- this tightens the suspensory ligaments 
- so the lens is pulled into a thin shape 
- the distant object is focused on the retina 


If you are looking at a near object: 
- the ciliary muscles contract
- this slackens the suspensory ligaments
- so the elastic lens goes flatter 
- The near object is focused on the retina