If refractive error RE is +2 D and accommodation is +1 D, what is the near point NP in meters?

If refractive error RE is +2 D and accommodation is +1 D, what is the near point NP in meters?

• A. 0.25 m
• B. 0.333 m
• C. 0.5 m
• D. 1.0 m

Answer: (B)

The near point is the closest distance at which the eye can form a clear image of a near object given its current refractive state and available accommodation. The eye’s total focusing power when viewing near is the sum of its refractive error and the accommodation it can exert. Since 1/NP equals the total optical power, you set 1/NP = RE + A. Therefore NP = 1 / (RE + A). Here, RE is +2 diopters and accommodation is +1 diopter, so RE + A = 3 D. NP = 1/3 m ≈ 0.333 m.

The near point is the closest distance at which the eye can form a clear image of a near object given its current refractive state and available accommodation. The eye’s total focusing power when viewing near is the sum of its refractive error and the accommodation it can exert. Since 1/NP equals the total optical power, you set 1/NP = RE + A. Therefore NP = 1 / (RE + A).

Here, RE is +2 diopters and accommodation is +1 diopter, so RE + A = 3 D. NP = 1/3 m ≈ 0.333 m.