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1. The brain sends nerve impulses to the ciliary muscles. Ciliary muscles relax, pulling on the suspensory ligaments.
2. Suspensory ligaments become taut, pulling on the edge of the lens.
3. The lens becomes thinner and less convex, increasing its focal length.
4. Light rays from the distant object are sharply focused on the retina.
5. Photoreceptors are stimulated.
6. Nerve impulses produced are transmitted by the optic nerve to the brain. 7. The brain interprets the impulses and the person sees the distant object.
1. The brain sends nerve impulses to the ciliary muscles when viewing a near object. Ciliary muscles contract, relaxing their pull on the suspensory ligaments.
2. Suspensory ligaments slacken, relaxing their pull on the lens.
3. The lens being elastic, becomes thicker and more convex, decreasing its focal length.
4. Light rays from the near object are sharply focused on the retina.
5. Photoreceptors are stimulated.
6. Nerve impulses produced are transmitted by the optic nerve to the brain. 7. The brain interprets the impulses and the person sees the near object.
II. When focusing on a distant object (> 4 metres)
The imaged formed at the retina is
1. vertically inverted
2. laterally inverted
3. real
4. diminished
Accommodation is also known as focusing.
Definition
Accommodation or Focusing refers to the changes in curvature of the eye lens when viewing objects at different distances from the eye. This is to produce a focussed image on the retina.
How is eye accommodation stimulated?
When light refracted by the cornea and lens reaches the retina, nerve impulses are sent to the brain. The brain then sends nerve impulses to the ciliary muscles to stimulate it to contract when focusing on a near object or relax when focusing on a distant object.
I. When focusing on a near object (< 70 cm)
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