SJWEH Supplements are open access, (mostly) non-peer-reviewed articles usually published in theme issues or as part of a series of papers from a conference or workshop. Scand J Work Environ Health stopped publishing SJWEH Supplements in 2009.


SJWEH Supplements 2007;(no 3):60-67    pdf

Accommodation–vergence performance after low levels of oculomotor load

by Richter HO, Crenshaw AG, Lyskov E

Objectives This experimental pilot study assessed the effects of sustained low-level accommodative vergence loads on oculomotor performance, eyestrain, and musculoskeletal functioning.

Methods A high-contrast fixation-point stimulus [light-emitting diode (LED)] was introduced into the optical axis of the viewing eye or into the midline in case of binocular viewing. The participants (N=6) were asked to compensate for the blur incurred by adjusting the strength of their eye lens. The participants performed in the following three standardized sequential viewing tasks: (i) resting with eyes open in darkness, (ii) accommodating alternately on a near versus a far LED illuminated sequentially (near–far response), and (iii) sustained fixation upon a LED at near. After the third task, the first and second tasks were repeated once.

Results The main effects of the third task were to decrease the overall rate of binocular accommodative relaxation time (diopters/s) in the repetition of the second task trial. The baseline shifts in individual response times also correlated with changes in the response amplitudes under the binocular stimulus conditions, which required contraction of the ciliary muscle.

Conclusions The results taken as a whole validate a technique of essential interest to applied vision research.