Insufficient lighting conditions and glare from luminaires in the visual environment can affect our visual ability and cause eyestrain, headache, and musculoskeletal strain. Knave et al. found that the frequency of reported glare was associated with more eyestrain. In this study a subjectively rated frequency of glare was compared to an objectively rated risk for glare made by trained assessors.

A visual ergonomics risk assessment method (VERAM) was used to gather data at workplaces, mainly computer workstations (n=420). Trained assessors (ergonomists) measured the luminance ratio and assessed the risk for glare (objective risk for glare) divided into three categories high risk (red), low risk (yellow) and no risk (green).Workers rated the frequency of experienced glare at their workplaces (subjective assessment of glare) via questionnaires. The frequency of subjective strain was divided into three categories; no, never; occasionally; a few times a week/almost always.

Workers rated the frequency of glare present more seldom than the trained assessors rated the presence for risk for glare, at the same workplaces. One factor behind this might be individuals’ ability to evaluate the visual environment such as risk for glare. A trained assessor can easier evaluate any risks in the visual environment.

When the objective risk for glare was assessed to be high (red) or low (yellow) the percentage of individuals reporting strain, such as eyestrain and musculoskeletal strain, increased for most symptoms compared to when there was no risk (green). An objective risk assessment for glare needs to be performed together with a subjective rating of the frequency of glare to find the individuals with problems.