Greater axial elongation associated with low accommodative lag: new insights on accommodative lag theory for myopia

PURPOSE We aimed to test the accommodative lag and mechanical tension theories for myopia by assessing the influence of the lag of accommodation on axial elongation by using three different near targets that are known to influence the accommodative response differently. METHODS Forty-two young adults were recruited for the study. Axial length was measured using a non-contact biometer, before and immediately after a 15 minute visual task, with one of the three near targets placed 20 cm from the eye: reading text from a paper, reading text from a smartphone and watching a video on a smartphone. The accommodative response was determined using an open-field autorefractor while the participants viewed the near target monocularly. RESULTS Lag of accommodation was significantly different for the three tasks: watching a video (mean ± standard error of the mean [SEM] 0.92 ± 0.10 D); reading text on the smartphone (0.59 ± 0.08 D); and reading text on paper (0.24 ± 0.09 D). There was a significant (p