Final answer:
The power of accommodation refers to the ability of the eye to focus on objects at different distances. For close vision, the eye has its greatest power, while for distant vision, it has its smallest power. As people age, they may lose the ability to accommodate, resulting in presbyopia.
Step-by-step explanation:
The power of accommodation of the eye refers to the ability of the eye to focus on objects at different distances. When the eye is fully accommodated, it has its greatest power for close vision. When the eye is totally relaxed, it has its smallest power for distant vision.
For close vision, the eye adjusts its focal length and power to converge the light rays from a nearby object, allowing them to form a sharp image on the retina. This requires a more powerful lens than for distant vision, where the light rays are nearly parallel.
As people age, they gradually lose the ability to accommodate, which can result in a condition called presbyopia. Presbyopia is characterized by a decreased ability to focus on near objects and can be corrected with reading glasses, which have a positive power lens.