Background: The purpose of this paper is to provide data on the binocular accommodative response (AR) as accommodative stimulus (AS) is changed with plus adds. This may be helpful in refining guidelines for prescribing nearpoint plus adds.
Methods: AR was measured with a Canon Autoref R-1 autorefractor on 50 subjects, 20 to 30 years of age. Letters were viewed at 40 cm through adds of 0 to +2.50D (0.25D steps) presented in random order.
Linear regression of AR on AS was performed to determine slope, y-intercept, add at which AR equaled AS, and add at which AR was 0.25D less than AS for each subject.
Results: The mean lag of accommodation (AS-AR) at the 2.50D stimulus level was 0.33D (SD=0.36). The mean slope was 0.51D/D (SD=0.16). The mean add at which AR was 0.25D less than AS was 0.29D (SD=0.71). There was significant inter-subject variability in each of these measures.
Conclusions: Accommodative response decreased as plus lenses were added, the decrease being about 51% on average. Because of the wide inter-subject variability in accommodative parameters,
lens powers for optimal nearpoint performance will vary from one individual to another.