2. Your grandfather has enjoyed good vision for most of his 80 years. You observ

Question

2. Your grandfather has enjoyed good vision for most of his 80 years. You observe him having trouble reading websites on his new iPad, squinting while he moves it towards and away from his face. You realize he might benefit from reading glasses. Since you were going out anyway, you offer to pick up a pair of glasses for him at the drug store. Consider that your grandfather is at his most comfortable reading posture when he is holding the iPad at a distance of 18 inches.

a. What visual condition is grandpa mostly suffering from, in medically-correct terminology? (1)

                                                                                                2a.___________________________

b. What dioptric power of reading glasses should you get for your grandfather? Note that reading glasses are normally available in increments of 0.25 Diopter. (2)

2b.___________________________

c. It occurs to you that you could have just shown grandpa how to make the displayed content appear larger on the iPad by adjusting the display “zoom”. What percentage zoom (100% is the default view, 200% would make text and images twice as large) would give your grandfather a similar viewing experience to wearing the reading glasses you were planning to purchase? (2)

Explanation / Answer

2. Grandfather might be suffereing from Presbyopia in medical terminologies.

Persons with Presbyopia condition suffers problems seeing the things which are more closer /near and it looks hazzy in appearance. It occurs with increasing age or older age .It results due to loss of flexibility of eye lens due to hardening leading to focus light behind the retina.

The distant objects still looks fine only the closer objects appear hazy, for this condition glasses can be a corrective measure.

b. 18 inches= 45.7 cm

The most comfortable distance for the grandfather is 45.7 cm, so from the most comfortable distance one can calculate correct lens power for the person. The accomodation amplitude decreses with age it becomes 1 D after the age of 50

generally +2.5 D or convex lens will be the better one.

c. Diopter signifies the optical power or capability of the lens

3D will be equals to nearly 1.75X magnification so doubling the zoom will be helpful to grandfather

so for 2.5 D it will be nearly 1.5X so zooming once (200%) will be better approximately same as viewing with the reading glasses.

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