I am familiar with lighting issues and requirements and I have opined on visibility and illumination cases in the past, usually in the automotive environment. I have completed both graduate and undergraduate coursework dealing with visibility and illumination issues. Unfortunately, the issue in this case is compounded by several factors which make a “cookie cutter” answer impossible. The level of illumination possible in a theater is constrained by the nature of the activity which occurs in that type of environment (showing movies), which essentially requires a dark environment. Further, the sensitivity of the human eye to illumination in a local area is not only a function of the level of illumination actually present, but also the level of illumination that the observer’s eyes are adapted too. A prosaic example would be the difficulty in seeing inside a darkened theater when the lights initially go down. It appears extremely dark. After some adaptation time, a moviegoer might then notice that he or she can readily see and identify individuals sitting on the far side of the theater from their position, even though those individuals were not initially even detectable. The light level has not changed, the viewer’s eyes have simply adapted to the available light level. A final consideration is the age of the viewer. As the eye ages, the lens yellows, the fluid inside the eye becomes progressively thicker, and the retinal mosaic becomes less sensitive. All of these combine to make it more difficult for older viewers to see clearly at light levels that younger viewers find more than adequate. A rule of thumb is that it requires roughly twice the light to see equally well for every decade of age beyond twenty-five. For example, it would require 2x2x2x2 times as much light for a 65-year-old to see as well as a 25-year-old. In general, when entering a dimly lit area, the appropriate action is to remain stationary for at least a short period to allow the eyes time to adjust to the prevailing light level to at least some degree prior to proceeding onward. Some theaters provide limited illumination in the form of pin lights or other low intensity, highly-focused illumination at ground level along entrance and egress paths, particularly at changes in elevation. These lights are typically adequate to indicate where the changes in elevation are located, but may or may not be adequate to allow an individual to assess the size of the change in elevation. The success of such illumination in preventing falls is, of course, a direct function of where an individual is looking prior to encountering the change in elevation–if they are looking at the walking surface, they can be quite effective. If the walker is looking upwards at the movie screen, no amount of illumination will be successful in making them aware of the change in elevation since their gaze is focused elsewhere.