- Amplitude of accommodation
Amplitude of accommodation (AA) is a measurement of the
eye’s ability to focus clearly on objects at near distances (i.e. accommodation). This eye focusing range for a child is usually about 5–7.5 cm (2–3 inches). For a young adult, it is 10–15 cm (4–6 inches). The focus range for a 45-year-old adult is about 50 cm (20 inches). For an 80-year-old adult, it is 1.5 m (60 inches). [http://www.vision-therapy.com/Glossary_of_Terms.htm]
The average amplitude of accommodation, in
diopters, for a patient of a given age may be estimated by Hofstetter's formula: 18.5 minus one third of the patient's age in years. [Scheiman, Mitchell and Wick, Bruce. "Clinical Management of Binocular Vision." Lippincott, New York. 1994.]
Negative relative accommodation
Positive relative accommodation
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