Dynamics of Accommodative Behavior Under Prolonged Viewing of Electronic Devices in Young Adults

The purpose of this study was to investigate the dynamic characteristics of accommodative behavior in non-myopic and myopic young adults under prolonged viewing of electronic devices.

Sixteen subjects aged 18 to 25 were recruited: 8 non-myopes (-0.25 to +2.0 diopters [D]), and 8 myopes (-0.50 to -6.0 D). Refractive state was assessed using an open-field autorefractor in dynamic mode. A comprehensive evaluation of accommodative behavior included (1) pre-task tonic accommodation (TA), computed as the difference in refraction before and after 5 minutes of dark adaptation, (2) refractive state during a 20-minute sustained near task at 25 cm on an iPhone, and (3) post-task adaptation over 3 minutes, under open-loop (open-loop accommodative adaptation [OLAA]) and closed-loop (near work-induced transient myopia [NITM]) conditions. Data were collected in two sessions for OLAA and NITM.

Pre-task TA (mean ± SD) did not differ significantly between refractive groups (P = 0.74 and 0.05 for the 2 sessions): non-myopes 0.15 ± 0.33 and 0.16 ± 0.22 D; myopes 0.10 ± 0.12 and -0.03 ± 0.08 D in the OLAA and NITM sessions, respectively. In both groups, refractive state and pupil size remained stable throughout the 20-minute near task, with no significant main effects of time, group, or time × group interaction (linear mixed-effects analysis, P ≥ 0.05). Subjects exhibited a typical accommodative lag of approximately 1.00 D (mean ± SD, non-myopes = 1.02 ± 0.06 and 1.08 ± 0.05 D; myopes = 1.09 ± 0.06 and 1.09 ± 0.08 D, in the OLAA and NITM sessions, respectively). Post task, NITM was more commonly observed than OLAA.

Prolonged near tasks did not significantly affect accommodative behavior of participants in either refractive group under open- or closed-loop conditions. Although accommodative adaptation was observed post-task, no systematic relationship was found between its magnitude or decay and refractive status.