Final answer:
Arcus senilis is the opaque band around the cornea found in elderly individuals, while presbyopia is a vision problem due to age where the eye loses its ability to focus on close objects and is corrected with a converging lens.
Step-by-step explanation:
The term for a narrow opaque band encircling the cornea, commonly observed in old age, with the recommended action to do nothing and refer to an optometrist, is a) Arcus senilis. This is not to be confused with presbyopia, which is another common vision problem associated with aging where the eye gradually loses its ability to focus on close objects, due to the loss of elasticity in the lens or weakening of the muscles that control it. The loss of the ability to accommodate close vision with age, termed presbyopia, is often corrected by the use of a converging lens to add power for close vision.