are bifocals needed mainly by older persons and not generally by younger people?
Step 1 of 1
Bifocals are needed for mainly the elderly as in the old age, there is a gradual weakening of the alary muscles with diminishing flexibility of the eye lens. Therefore, the near point of the old person gradually recedes and becomes more than 25 cm. This defect is called presbyopia. Such people have both defects of vision namely myopia and hypermetropia.
Therefore, a person suffering from this defect uses spectacles having bi-focal lenses that is the upper half part consists of a concave lens used for distant vision and the lower half having convex lens used for reading purposes.
In case of younger people, the alary muscles are flexible. So, presbyopia is not present.
Textbook: Physics: Principles with Applications
Author: Douglas C. Giancoli
Physics: Principles with Applications was written by and is associated to the ISBN: 9780130606204. The answer to “are bifocals needed mainly by older persons and not generally by younger people?” is broken down into a number of easy to follow steps, and 13 words. This full solution covers the following key subjects: bifocals, generally, mainly, needed, older. This expansive textbook survival guide covers 35 chapters, and 3914 solutions. The full step-by-step solution to problem: 4Q from chapter: 25 was answered by , our top Physics solution expert on 03/03/17, 03:53PM. Since the solution to 4Q from 25 chapter was answered, more than 543 students have viewed the full step-by-step answer. This textbook survival guide was created for the textbook: Physics: Principles with Applications, edition: 6.