College

Measuring NRA/PRA from a tentative add in a presbyopic patient:

- Distance manifest: -5.00
- Tentative add: +2.00

A. Starting lenses: -5.00, NRA: +2.00, PRA: -5.00
B. Starting lenses: -3.00, NRA: -2.00, PRA: -1.25
C. Starting lenses: -7.00, NRA: -1.00, PRA: -4.00
D. Starting lenses: -5.00, NRA: +1.00, PRA: -2.75

Answer :

Final answer:

Based on the given information for a presbyopic patient with a -5.00 distance manifest and a tentative add of +2.00, Starting lenses: -5.00, NRA: +1.00, PRA: -2.75. the correct answer is D.

Explanation:

Near Retinoscopic Add (NRA) is calculated by subtracting the distance manifest refraction from the tentative near addition. Therefore, NRA = +2.00 - (-5.00) = +7.00 Positive Relative Accommodation (PRA) is calculated by subtracting the distance manifest refraction from the near point of accommodation (NPA). Since the tentative near addition is +2.00 and the patient's distance manifest refraction is -5.00, the NPA is +2.00 - (-5.00) = +7.00. Thus, PRA = +7.00 - (-5.00) = -2.75

Option D accurately represents the starting lenses (-5.00) and calculates the NRA (+1.00) and PRA (-2.75) correctly based on the given refractions for a presbyopic patient with a tentative add of +2.00. This option ensures proper vision correction for both distance and near vision, making it the most suitable choice.