Which of the following statements correctly describes the changes that occur in the eye during accommodation for a near object?
Answer
B) The ciliary muscle contracts, suspensory ligaments slacken, and the lens becomes more convex.
The correct answer is B) The ciliary muscle contracts, suspensory ligaments slacken, and the lens becomes more convex. — Match these facts with the given options and select the correct one.
Step-by-step solution
- Recall that accommodation involves focusing on a near object.
- Remember that for near vision, the lens must increase its curvature (become more convex).
- Identify the muscle action that allows the lens to become more convex: the ciliary muscle contracts.
- When the ciliary muscle contracts, it reduces tension on the suspensory ligaments, allowing them to slacken.
- With slackened ligaments, the elastic lens bulges, increasing its curvature.
- Match these facts with the given options and select the correct one.
Common mistake: Confusing the effect of ciliary muscle relaxation with lens flattening, leading to selection of option A or D.
Concept tested: Accommodation mechanism
Published · How this solution was prepared and checked
Related questions
- 1 Describe what happens to the ciliary muscle, suspensory ligaments and the shape of the lens when the eye focuses on a near object.
- 2 Which part of the eye contributes the greatest refractive power?
- 3 A person with a myopic eye can see clearly up to a distance of 1.2 m. What is the nature and power of the lens required to correct this defect of vision?
- 4 A myopic person sees distant objects clearly only up to a far point of 50 cm. What is the minimum power of a lens (in dioptres) required to correct his vision so that he can see objects at infinity clearly? Assume a thin lens placed close to the eye.
- 5 List three common causes of eye injuries in daily life and suggest one preventive measure for each cause.
- 6 A hyperopic person can see distant objects clearly but cannot read a newspaper held at 25 cm without glasses. The far point of his eye is at infinity. Calculate the minimum power (in dioptres) of a thin converging lens that should be placed close to the eye to enable him to read at 25 cm.