An office administrator realizes that she is having trouble doing her work due t

Question

An office administrator realizes that she is having trouble doing her work due to eyesight problems. Her optometrist determines that without glasses she can focus clearly only on objects that lie at distances between 0.620 m and 4.30 m. The optometrist decides that the best way to handle her eyesight problems is to prescribe bifocals that will give her normal visual acuity from 25.0 cm out to infinity. After trying on several pairs of glasses frames, they agree that the glasses will be a distance of 2.20 cm from her eyes.

(a) Determine the refractive power needed for the bifocal part that will correct for her nearsightedness (include the sign).

(b) Determine the refractive power needed for the bifocal part that will correct for her farsightedness (include the sign).

Explanation / Answer

(a)

Refractive power is,

P = 1 / f = 1/v + 1/u

For the correction for her nearsightedness,

1/f = 1/25 + 1/-(0.62 + 0.022)

P = -1.517 D

(b)

For the correction for her farsightedness,

P = 1/f = 1/infinity + 1/-(4.30 + 0.022)

P = -0.231 D

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