Distance, lighting, and parental beliefs: understanding near work in epidemiologic studies of myopia.
OBJECTIVE
To develop measures and indices of factors (distance of eye from object, posture, and lighting) that may modify a possible effect of near work activity on myopia.


METHODS
The duration of near work, the distance of an object from eye, lighting conditions, and other sociodemographic characteristics were asked in an interview. Both distance and lighting information from the questionnaire were compared with more precise measurements.


RESULTS
Diopter hours were quantified as the duration of near work multiplied by the reciprocal of the distance which the activity was performed. The intraclass correlation coefficient of the reliability of distance information for each type of near work activity ranged from 0.43 to 0.91. Home light meter readings were significantly higher for children who were reading under both room and reading light, and the distances from the questionnaire were comparable to the measured distances.


CONCLUSIONS
Measures of posture, distance, and lighting factors have been developed to study the possible effect modifiers of the effects of near work on myopia.
Saw
S M
SM
Department of Community, Occupational and Family Medicine, National University of Singapore, Singapore. cofsawsm@nus.edu.sg
Nieto
F J
FJ
Katz
J
J
Chew
S J
SJ
D000065:Accommodation, Ocular; D002648:Child; D015331:Cohort Studies; D018450:Disease Progression; D004215:Distance Perception; D006801:Humans; D008029:Lighting; D009216:Myopia / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D010287:Parent-Child Relations; D016487:Parenting; D011187:Posture; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D012846:Singapore / Q000453:epidemiology; D011795:Surveys and Questionnaires