Which formula expresses Hofstetter's minimum amplitude of accommodation?

Which formula expresses Hofstetter's minimum amplitude of accommodation?

• A. 15 - 1/4(age)
• B. 18.5 - 1/3(age)
• C. 25 - 0.4(age)
• D. 20 - age

Answer: (A)

Hofstetter's formulas estimate how much accommodation a person can have based on age. The smallest expected amount is given by subtracting one quarter of the person's age from 15 diopters. This captures the idea that younger individuals can accommodate more, and the minimum expected amount decreases as age increases. The other two standard expressions give the average and maximum predicted amplitudes: about 18.5 minus one third of age, and 25 minus one half of age, respectively. So the correct expression for the minimum amplitude of accommodation is 15 − age/4. For example, a 20-year-old would have a minimum predicted AA of 15 − 5 = 10 D, illustrating how the minimum declines with age.

Hofstetter's formulas estimate how much accommodation a person can have based on age. The smallest expected amount is given by subtracting one quarter of the person's age from 15 diopters. This captures the idea that younger individuals can accommodate more, and the minimum expected amount decreases as age increases. The other two standard expressions give the average and maximum predicted amplitudes: about 18.5 minus one third of age, and 25 minus one half of age, respectively. So the correct expression for the minimum amplitude of accommodation is 15 − age/4. For example, a 20-year-old would have a minimum predicted AA of 15 − 5 = 10 D, illustrating how the minimum declines with age.