Abstract OBJECTIVES: The aim of this study was to evaluate the luminance level of monitors as a function of the burning time of the lamp in the monitor and further to evaluate if different areas of the monitor varied in luminance levels at a specific time. MATERIAL AND METHODS: Nine standard liquid crystal display (LCD) monitor models, in total 180 monitors, were evaluated. The monitors' maximal luminance levels were measured, and the burning times of the lamps were noted. The estimated function between burning time and luminance was calculated. On 11 monitors, 9 areas distributed over the full screen were measured to evaluate the extent to which different areas had different luminance levels. RESULTS: Over time, the luminance decreased in all monitor models. No difference was found among the monitor models in how rapidly the luminance levels decreased. Different luminance values were found for different areas on the monitors, but no area deteriorated faster than another. CONCLUSIONS: Standard liquid crystal display monitors undergo gradual deteriorations in luminance levels over time, and these deteriorations are correlated with the time that the monitors have been switched on. The degradation in luminance is similar over all areas of the monitors.