Variation of Ambient Illumination Across Different Locations: An Impact on Antimyopia Strategy.

Purpose: To evaluate whether the level of ambient illumination in winter at different locations, time of a day, sun protection, and source position remains optimum (≥1000 lux) for controlling myopia progression.

Methods: Illuminance level was recorded for 6 outdoor and 5 indoor locations using factory calibrated digital lux meter and under different measurement conditions. Outdoor locations included "open playground," "between two buildings," "between three buildings," "under a porch facing east," "under a big tree," and "under a porch facing west.