Assessment Methods and Causes of Eye Irritation in Humans in Indoor Environment. In: Knöppel H, Wolkoff P, editors. Chemical, Microbiological, Health and Comfort Aspects of Indoor Air Quality — State of the Art in SBS. Dordrecht: Springer Netherlands; 1992. pp. 115-27. [DOI: 10.1007/978-94-015-8088-5_9]

Self-reported eye symptoms and related diagnostic findings--comparison of risk factor profiles

Profiles of factors affecting self-reported eye symptoms and objectively determined tear film characteristics have been examined and compared using data from 814 office workers. Multiple logistic regression analysis reveals significantly increased risks of subjective perception of eye symptoms for female gender, use of contact lenses and persons with health problems. A reduced break-up time (BUT) depends on personal criteria such as a history of eye disease and female gender. Age under 40 years, high relative humidity and formaldehyde exposure exceeding the 90th percentile are protective regarding BUT. For a thin lipid layer (as an indication of dry eyes) significantly increased risks are detected for high particle load, high endotoxin concentration and female gender. A thick lipid layer (as an indication of inflamed eyes) is significantly associated with a low educational level. The estimation of foam in the medial eye canthus seems to be unsuitable for evaluating indoor problems. The risk factor profiles agree on a few points only. The objectively examined thin lipid layer is the best eye-related indicator of the indoor environment. We therefore conclude that there is a need for the development and application of objective clinical methods for field monitoring in parallel with questioning.

PRACTICAL IMPLICATIONS

Self-reported eye symptoms in conjunction with indoor environmental problems should be validated by objective medical examinations such as semi-quantitative estimation of the superficial lipid layer, measurement of the break-up time or assessment of conjunctival epithelial damage. For unbiased proof of environmental impact, personal factors such as acute illness or low job satisfaction should be excluded. As a minimum requirement, measurements of particles, NO(2) and relative humidity (and if possible endotoxin) should be carried out to detect any indoor environmental reason for eye symptoms.

Eye trigeminal sensitivity, tear film stability and conjunctival epithelium damage in 182 non-allergic, non-smoking Danes

The population distributions of CO(2)-induced irritation sensitivity in the eyes (COI), tear film stability (break-up time, BUT), and epithelium damage (ED) and the relation of these to basic potential confounders were assessed in an age- and gender-stratified random sample of citizens in Aarhus County, Denmark. One hundred eighty-two non-allergic, non-smoking persons participated. A general health questionnaire and an indoor air questionnaire was filled out before the measurements. The BUT was non-normally distributed, as was COI at 16% CO(2) and single ED-scores. However, COI average for all levels was normally distributed and the total score for ED was only marginally deviating. BUT decreased, the threshold to CO(2) increased, and irritation intensity at CO(2) eye exposure decreased with increasing age. ED was increased among women. There were no internal relations between the three measures, but reduced BUT was seen among subjects rating high levels of exposure to dust, electrostatic fields, and dry air. ED decreased by perceived unpleasant odors and increased with experiences of high temperatures. CO(2) sensitivity increased by perceived draught, dry air, and noise exposure prior to measurements. Selection bias cannot be excluded and the results may therefore not be truly representative of the general population. However, the results may be used as reference data for future use of measurements of break-up time, epithelium defects, and CO(2) sensitivity of the eyes in the indoor air.

PRACTICAL IMPLICATIONS

The most direct implication is that results can be used as reference level for measurements in problem buildings and for individual measurements. The reference can also be used in research and the other results as basis for future hypotheses and for support of existing hypotheses.