Hofstetter’s equations overestimate the amplitude of accommodation in human eye: An analyses of 5433 subjects

Abstract

Abstract Purpose The set of Hofstetter equations is a widely used theoretical framework for predicting the temporal evolution of amplitude of accommodation (AA). However, studies have reported discrepancies between the measured values of AA and prediction from Hofstetter’s formulas. Here, the relationship between AA and age was investigated in a comprehensive cohort of subjects and compared with Hofstetter equations. Methods Based on the PRISMA strategy, an extensive online survey was performed to collect the reported values of AA as a function of age. Regression analyses were employed to derive three equations, describing the minimum, maximum and mean declining trend of the AA data with age. This set of equation was subsequently compared with the corresponding three equations from Hofstetter. Results The AA data were collected for large number of subjects (n = 5433). Subsequent analyses revealed that the AA values predicted by all three Hofstetter equations are consistently higher than the corresponding values predicted by the regression equations derived in the current study. Specifically, the intercepts and slopes for the minimum, maximum and mean of equations from Hofstetter and from this study were (15, 18.5, 25) vs. (9, 14.9, 22.4) and (-0.25, -0.3, -0.4) vs. (-0.15, -0.24, -0.35), respectively. Conclusions The findings of this study support the postulate that the Hofstetter’s equations overestimate the declining AA as function of age.