2.87 Understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity
Focusing Near and Distant Object
Cornea bends light to bring them to a focus on retina.
Lens sharpen the image and makes it "clear".
For far objects, the rays of light entering the eyes are almost parallel. This means it requires less bending to bring focus on retina.
As a result the ciliary muscle relaxes --> suspensory ligaments pulls the lens to make it thin
For near objects, the rays of light entering the eyes are greatly diverged. Therefore more bending is required for focusing.
Ciliary muscle then contracts, reducing tension on the lens. The lens then "snap" back into fatter shape, bending light more.
Changes in light intensity
Iris control the amount of light entering the eyes by changing the size of pupil.
It contains circular and radial muscles.
Bright = circular muscles contract, radial muscles relax
This makes pupil smaller and less light can enter the eyes.
Too much light entering the eyes can do damage.)
Dim = circular muscles relax, radial muscles contract
This makes pupil bigger and so more light can enter the eyes
This helps us see in darker places (the eyes is trying to collect as many light as possible to see clearly)
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