Which formula expresses Hofstetter's maximum amplitude of accommodation?

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

Answer: (A)

Maximum accommodation is the greatest focusing power a normal eye can achieve, and Hofstetter described it as an age-dependent upper boundary. The idea is that younger eyes can focus much more, and this ability declines with age as the lens becomes stiffer and the ciliary apparatus less effective. The line that best fits the observed data for this maximum capacity has an intercept near 25 diopters and a steady decline of about 0.4 diopters per year. That’s why the expression is 25 minus 0.4 times age.

This form gives realistic values across common ages: for example, at age 10 it’s about 21 D, at age 30 about 13 D, and at age 60 about 1 D. It represents the upper limit of what a person can accommodate, against which actual patient performance can be compared. The other commonly cited lines describe the average and the minimum expected amplitudes, which are lower than the maximum and used for different benchmarks.