Question

What is the approximate amplitude (power) of accommodation in a 7-year-old child?

• A. +14 D
• B. +10 D
• C. +5 D
• D. +2 D

Hint:

Hofstetter: amplitude = 18.5 − 0.3 x age; young children have the highest value.

Answer 1

The Correct Option is A

Step 1: Recall the concept.
The amplitude of accommodation is the maximum increase in dioptric power the eye can generate by contracting the ciliary muscle to focus on near objects. It is highest in childhood and falls progressively with age as the crystalline lens loses elasticity (eventually causing presbyopia).

Step 2: Apply Hofstetter’s formula.
A standard estimate of the average (probable) amplitude of accommodation is:
\[ A = 18.5 - (0.30 \times \text{age}) \]
For a 7-year-old:
\[ A = 18.5 - (0.30 \times 7) = 18.5 - 2.1 = 16.4\ \text{D} \]
The closest standard textbook value quoted for a young child is about +14 D, so option (a) is correct (+10 D and +5 D correspond to much older ages).

Step 3: Cross-check with the age trend.
Accommodation is roughly 14 D in early childhood, ~7-8 D in early adulthood (about age 20), ~4 D by 40 years, and falls to ~1 D by 60 years. A value of +14 D fits a 7-year-old far better than +10 D or +5 D.

Key fact: A young child (~7 years) has an accommodative amplitude of about +14 D; it declines steadily with age.