What is Hofstetter's formula for the maximum amplitude of accommodation?

• A. 25 - 0.4(age)
• B. 18.5 - 1/3(age)
• C. 15 - 1/4(age)
• D. 20 - 0.5(age)

Answer: (A)

Hofstetter’s formulas describe how the eye’s ability to focus up close changes with age, and the maximum amplitude of accommodation is given by 25 minus 0.40 times age. This means the strongest focusing power a person can muster decreases by about 0.40 diopters each year, starting from an approximate 25 diopters at a very young age. That’s why this option is the best choice for maximum accommodation.

The other common Hofstetter formulas describe different expectations: the average amplitude is around 18.5 minus 0.30 times age, and the minimum amplitude is about 15 minus 0.25 times age. So the form 18.5 minus one-third age or 15 minus one-fourth age corresponds to those other categories, not the maximum. The value 20 minus 0.5 age isn’t one of Hofstetter’s standard formulas for maximum, average, or minimum.

For a quick sense, at age 30 the maximum AA would be roughly 25 minus 12, equaling about 13 diopters.