Optometry & Vision Science

Skip Navigation LinksHome > January 2013 - Volume 90 - Issue 1 > Visual Fatigue and Accommodative Dynamics in Asymptomatic In...
Optometry & Vision Science:
doi: 10.1097/OPX.0b013e31827a233e
Original Articles

Visual Fatigue and Accommodative Dynamics in Asymptomatic Individuals

Thiagarajan, Preethi*; Ciuffreda, Kenneth J.

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Abstract

Purpose: To evaluate accommodative dynamics immediately before and after visual fatigue-inducing tasks with congruent (C) and noncongruent (NC) visual stimuli.

Methods: Accommodative dynamics for a 2-diopter (D) step (2.5 ↔ 4.5 D) stimulus were assessed using the WAM-5500 open-field autorefractor in 10 visually normal, asymptomatic, young-adult subjects before and after C and NC tasks performed on different days in a counterbalanced manner. For the C task, subjects altered binocular fixation (50 cycles) between reduced Snellen charts at 50 and 20 cm every 3 seconds to the beat of a metronome. For the NC task, subjects performed 50 cycles of accommodative flipper (±1.5 D) as rapidly as possible while binocularly fixating on a reduced Snellen chart at 40 cm.

Results: Mean steady-state (SS) response level reflecting its accuracy was significantly (p ≤ 0.05) reduced post-NC task for both increasing (4.5-D level) and decreasing (2.5-D) accommodation. Although the SS response variability was significantly (p ≤ 0.05) increased post-NC task at the 4.5-D stimulus level, it did not change significantly (p > 0.05) for the C task. There were no significant differences between the pretask and posttask group mean initial amplitude, time constant, and peak velocity for either the C or the NC task for both increasing and decreasing accommodation.

Conclusions: The accommodative system exhibited consistent fatigue effects with respect to SS variability and response accuracy. There was no objective evidence of oculomotor learning for these specific tasks.

© 2013 American Academy of Optometry

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