The normal range of PRA (Positive Relative Accommodation), also known as accommodative amplitude, is typically considered to be around -2.37 ± 1.00 D (Diopters), according to Scheiman and Wick. However, it's important to note that "normal" values can vary depending on several factors.
While a mean PRA of -2.37 ± 1.00 D is a common benchmark, the actual accommodative amplitude can be influenced by:
- Age: Accommodative amplitude generally decreases with age, a condition known as presbyopia.
- Testing conditions: The specific method and parameters used for measuring PRA can affect the results.
- Individual variability: There is natural variation in accommodative ability among individuals.
Therefore, while the -2.37 ± 1.00 D range provides a general guideline, a comprehensive eye exam performed by an eye care professional is necessary to determine what's considered normal for a specific individual, taking into account their age, visual demands, and overall eye health. A significantly lower-than-expected PRA might indicate an accommodative dysfunction that requires further investigation and management.
