Final answer:
The usage of contact lenses drops off dramatically around the age of 40 due to presbyopia, the gradual loss of ability to accommodate. Reading glasses with positive power lenses can be used to correct presbyopia.
Step-by-step explanation:
The usage of contact lenses drops off dramatically with age, typically around the age of 40. This is because as people age, they gradually lose the ability to accommodate, or adjust the focus of their eyes to see objects up close. This condition is called presbyopia, and it is caused by the stiffening of the lens of the eye.
To correct presbyopia, a converging, positive power lens can be used. Reading glasses, which are commonly available, have power in diopters and are rated from 1.0 to 3.5 D.