Minus-lens-stimulated accommodative amplitude decreases sigmoidally with age: a study of objectively measured accommodative amplitudes from age 3

Abstract

Purpose: Guidelines for predicting accommodative amplitude by age are often based on subjective push-up test data that overestimate the accommodative response. Studies in which objective measurements were used have defined expected amplitudes for adults, but expected amplitudes for children remain unknown. In this study, objective methods were used to measure accommodative amplitude in a wide age range of individuals, to define the relationship of amplitude and age from age 3.

Methods: Accommodative responses were measured in 140 subjects aged 3 to 40 years. Measurements were taken with the Grand Seiko autorefractor (RyuSyo Industrial Co., Ltd., Kagawa, Japan) as the subjects viewed a high-contrast target at 33 cm through minus lenses of increasing power until the responses showed no further increase in accommodation.

Results: The maximum accommodative amplitude of each subject was plotted by age, and a curvilinear function fit to the data: y = 7.33 - 0.0035(age - 3)(2) (P < 0.001). Tangent analysis of the fit indicated that the accommodative amplitude remained relatively stable until age 20. Data from this study were then pooled with objective amplitudes from previous studies of adults up to age 70. A sigmoidal function was fit to the data: y = 7.083/(1 + e([0.2031(age-36.2)-0.6109])) (P < 0.001). The sigmoidal function indicated relatively stable amplitudes below age 20 years, a rapid linear decline between 20 and 50 years, and a taper to 0 beyond 50 years.

Conclusions: These data indicate that accommodative amplitude decreases in a curvilinear manner from 3 to 40 years. When combined with data from previous studies, a sigmoidal function describes the overall trend throughout life with the biggest decrease occurring between 20 and 50 years.

FIGURE 1

Examples of accommodative stimulus response functions for two subjects. Solid line: 1:1 stimulus/demand line; (●) represent the subject's accommodative response. In each plot, the circle represents the point of maximum accommodative response. (A) A 17-year-old subject whose response peaked and declined with increasing demand. (B) A 19-year-old subject whose response peaked and plateaued.

FIGURE 2

Maximum accommodative amplitudes for subjects aged 3 to 40 years. The six circled data points represent potential outliers, all of whom had studentized residuals with a z-score of less than −2.00.

FIGURE 3

Comparison of maximum accommodative amplitudes measured using minus lens blur as a stimulus for accommodation versus proximal blur as a stimulus for accommodation in 22 adult subjects. (A) Linear regression analysis. (B) Difference-versus-mean plot. Solid line: mean difference between methods; dashed lines: 95% limits of agreement (±1.96 SD).

FIGURE 4

Maximum accommodative amplitudes for subjects pooled from the present study and four previous published studies: Ostrin and Glasser, Wold et al., Koretz et al., and Hamasaki et al.

FIGURE 5

Maximum accommodative amplitudes from previous studies using the subjective push-up test are shown in comparison to the sigmoidal function of objective accommodative amplitudes presented in the present study: Sterner et al., Eames, Wold, and Woodruff. Solid line: the predicted line of Hofstetter for mean accommodative amplitude; dashed line: predicted function presented in this study for objective accommodative amplitudes.