Final answer:
Age-related macular degeneration (AMD) is the most common cause of blindness in the U.S. elderly population. It occurs when cells of the macula die, leading to a black spot in the center of vision.
Step-by-step explanation:
The most common cause of blindness in the U.S. elderly population is age-related macular degeneration (AMD). AMD occurs when cells of the macula, which is responsible for high visual acuity, die. As a result, patients experience a black spot in the center of their vision, which grows outward as the disease progresses.