Final answer:
The basic design of Ultra for presbyopia involves concentric rings for multifocality (option A), allowing for simultaneous clear vision at different distances through the alternating rings of different focal powers.
Step-by-step explanation:
The basic design of Ultra for presbyopia is based on the concept of multifocality. The design commonly involves concentric rings, with alternating rings providing different focal powers for distance and near vision. This approach enables simultaneous vision, allowing someone with presbyopia to see clearly at different distances. These lenses utilize a series of rings to create zones of different powers, mimicking the natural ability of a younger eye to change focus (accommodation).
Presbyopia is a condition where the eye's lens loses elasticity, leading to difficulty in focusing on close objects. To correct this issue, a converging lens is added for close vision, improving the eye's ability to accommodate by increasing its power. The vision correction for presbyopia at the lens-to-retina distance typically involves an 8% increase in power for close vision.