A research team in Taiwan measured lamps in the market and found that nearly all the desk lamps are too bright that they may damage the eye.
Jwo-Huei Jou, professor at Taiwan’s National Tsing Hwa University (NTHU), and his team consisting of student from Shu Guang Girl's Senior High School and Ho-Shin Chen and NTHU, measured that white CFL with a color temperature of 5600K at an illuminance of 101 lux permits 29-minute reading time, and white LED of 5300K at 196 lux permits only 13 minutes. Situation would become worse with a blue light-enriched background light.
The team found that if 50-minute is a reasonable reading or working time span, candlelight, having an around 1,600K color temperature, can be lit up to 400 lux. Contrarily, typical white light of 6,000K must be dimmed to 50 lux to prevent causing retina inflammation. Brighter candlelight makes it easier to read fonts of smaller sizes. Also, low blue or blue hazard-free light is recommended.
Dr. P.T Yeh, ophthalmologist of National Taiwan University Hospital, further addressed that lights that are too bright or too dark, might lead to high eyestrain and frequent reading under such an environment could lead to myopia.