which of the following occurs when a person focuses on a nearby object (less than 20 ft away)?

a.ciliary zonule tightens
b. ciliary muscle contract
c. lens flattens
d. two of the above
e. all of the above

Solutions

Expert Solution

ciliary muscle contract

The ciliary muscle is a ring of smooth muscle in the eye's middle layer that controls accommodation for viewing objects at varying distances

zonular fibers present in the eye that suspend the lens in position during accommodation

zonular fibers hold or flatten the lens

The circular ciliary muscle fibers affect zonular fibers in the eye enabling changes in lens shape for light focusing

When the ciliary muscle contracts, it pulls itself forward and moves the frontal region toward the axis of the eye. This releases the tension on the lens caused by the zonular fibers causes the lens to become more spherical, adapting to short range focus.

The effect of contraction is to decrease the diameter of the ring of ciliary muscle. The zonule fibers relax and the lens becomes more spherical, increasing its power to refract light for near vision.

Conversely, relaxation of the ciliary muscle causes the zonular fibers to become taut, flattening the lens, increasing the focal distance increasing long range focus.

gladiator answered 1 year ago

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