Measuring glare induced visual fatigue by fixation disparity variation.

Area of Science:

• Ophthalmology
• Optometry
• Human Factors

Background:

• Visual discomfort and fatigue are common issues, particularly with prolonged screen use.
• Fixation disparity is a measure of eye alignment during visual tasks.
• Existing measures of visual fatigue are often subjective.

Purpose of the Study:

• To introduce fixation disparity variance as an objective metric for visual discomfort.
• To investigate the effect of glare on fixation disparity and its variance.
• To determine if fixation disparity variance correlates with visual fatigue.

Main Methods:

• A balanced repeated-measurement experiment involving 16 participants with normal vision.
• Near-vision tasks were performed under four lighting conditions: no glare, direct light, indirect light, and desk luminary.
• Fixation disparity was measured 15 times per condition using a computerized test.

Main Results:

• Average fixation disparity showed a trend towards esophoria with increasing glare adversity, though not statistically significant.
• Fixation disparity variance (standard deviation) was significantly higher under direct light conditions compared to no glare and desk luminary.
• This suggests glare intensity influences the variability of fixation disparity.

Conclusions:

• Fixation disparity variance shows promise as an objective measure of visual fatigue.
• The findings support the use of fixation disparity variance in assessing visual discomfort caused by environmental factors like glare.
• Further research can validate this metric in diverse visual environments and tasks.