Accommodation response and visual discomfort

Abstract

Although visual discomfort symptoms associated with near work have been correlated with clinical measures of accommodation, studies using objective recordings have not found corresponding deficits in accommodative function. One problem with previous studies is that accommodation measures have been too brief to assess accommodative fatigue. This study examined steady state accommodative responses among a college population with visual discomfort, over a 90-s time period. Thirty-one participants were grouped into high (n = 15) or low visual discomfort groups (n = 16) based on their scores on the Conlon Visual Discomfort Survey. Using the WAM-5500 autorefractor, accommodation responses were recorded at 5 Hz for two consecutive minutes at five viewing distances. The results showed a significant interaction between the high and low discomfort groups over time in accommodation response. The high discomfort group showed an increase in accommodative lag, whereas the low discomfort group had a stable response. Our study suggests that the high visual discomfort group is characterized by accommodative fatigue, with a higher lag of accommodation developing at a near viewing distance over time.

Accommodation to Uncomfortable Patterns

“…Tosha et al (2009) found that participants with high visual discomfort showed significant signs of fatigue when the distance of the target was 4D compared to 2D. Chase et al (2009) also found larger lags in those with high visual discomfort when viewing targets at 4-5D.…”

“…Tosha et al (2009) found effects of fatigue between individuals with high and low visual discomfort after 60 seconds of viewing the stimulus. However, when using the Pattern Glare Test (which measures the number of illusions reported in grating patterns that vary in their spatial frequency) each pattern is only presented to the participant for 3 seconds (Wilkins & Evans, 2001), and yet individuals report discomfort and illusions.…”

“…Several studies have found an effect of pattern glare/visual discomfort on accommodation (Allen et al, 2008;Chase et al, 2009;Tosha et al, 2009). Individuals who experience discomfort tend to have a greater lag of accommodation.…”

“…Tosha et al (2009) also found that a group which reported high discomfort showed greater fatigue when sustaining accommodation at near distance (3-4D), even over a short time period (90s).…”

The effect of viewing distance on responses to the pattern glare test

“…Accommodative fluctuations have been reported to be greater in individuals who experience visual distortions and benefit from coloured filters. 18 The accommodative lag is greater in individuals who report visual discomfort 19,20, and pattern glare, 21 although these differences may take time to appear and be more apparent at close viewing distances. 20 Close viewing distances affect not only accommodation but also vergence.…”