Subjective and objective measurements of the amplitude of accommodation: Revisiting the existing methods and clinical evaluation of newer techniques.

Purpose: To evaluate the repeatability and agreement of established and newer methods for measuring the amplitude of accommodation in non-presbyopic and early presbyopic individuals.

Methods: The amplitude of accommodation of 81 participants was measured using five different methods (two push-up techniques, two minus lens techniques and one objective technique) with different measurement principles. Among these, two new techniques were introduced: an electronic push-up and a minus lens technique with a tunable lens. Three repeated measurements were performed with each method. The repeatability limit and non-parametric Bland-Altman analysis were used to describe the repeatability and agreement of each method.

Results: The repeatability limit was between ±0.7 D and ±1.4 D for the minus lens techniques, around ±1.8 D for the push-up methods and ±1.4 D for the objective procedure. The largest differences in median values were found between the push-up and objective methods.

Conclusions: Push-up methods are most likely to overestimate accommodation, while the objective method gives the lowest results. New techniques show good repeatability for measuring the amplitude of accommodation. Among the subjective methods, the minus lens technique with the tunable lens gives the best repeatability, is one of the fastest and gives results most similar to the objective method.