Occupational Factors Affecting the Accommodative Response in the Human Vision System

Abstract

Accommodative microfluctuations (AMFs) are temporal variations in the accommodative response. AMFs can be divided into two categories, the low frequency component (LFC) measuring below 0.6 Hz and the high frequency component (HFC) measuring between 1.0 and 2.3 Hz. This thesis examined occupational factors that may affect AMFs comprising of cognitive demand, visual fatigue and the type of digital display used. These effects were measured by assessing changes in the LFC, mid frequency component (MFC), HFC, and RMS accommodation. Analysis of chaos and the overall accommodative response (AR) was also used. Furthermore, an investigation into inter- and intra-participant variability was completed. The HFC was shown to increase in line with increasing cognitive demand. A significant effect for task duration was found at higher accommodative demands for the overall AR, LFC and MFC. There was a significant effect on the LFC and AR depending on the type of display used during near work. The HFC and MFC were found to be less repeatable in the same participant relative to LFC, RMS accommodation and AR measurements. AMFs appear to have an effect on occupational factors, however more research is required to assess how much of an effect they may have relative to other ocular factors that affect occupational settings.