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Multiple Choice
Which structure changes shape to focus light on the retina?
A
Iris
B
Cornea
C
Retina
D
Lens
Verified step by step guidance
1
Understand the function of each structure listed in the question: The iris controls the size of the pupil to regulate the amount of light entering the eye, the cornea provides most of the eye's refractive power but does not change shape, the retina is the light-sensitive layer where images are formed, and the lens adjusts its shape to focus light on the retina.
Recall the process of accommodation: The lens changes its curvature to focus light from objects at varying distances onto the retina. This is achieved through the action of the ciliary muscles.
Identify the key characteristic of the lens: It is flexible and capable of changing its shape, unlike the cornea, which is fixed in shape.
Eliminate incorrect options based on their functions: The iris regulates light entry, the cornea provides fixed refraction, and the retina processes light signals but does not focus light.
Conclude that the lens is the structure responsible for changing shape to focus light on the retina, as it is the only structure capable of dynamic adjustment for focusing.