I'm struggling with this method. for some time now. I'm going to use ethidium bromide staining method but it occured to me that my epifluorescent microscope may not be enough for observation of cell nuclei.
we use a pretty old epifluorescence microscope with a 25x objective and an even older 768x576 grayscale CCD camera for visualization and evaluation of EtBr-stained nuclei from cultured cells. The resolution and sensitivity is adequate for routine analysis, but I assume it may be improved using up-to-date hardware, especially a better camera.
What exactly are your concerns and what kind of microscope / camera do you intend to use?
Epifluorescence microscope with 25× objective (long working distance objective is best) and filter set for green-light excitation if using propidium iodide to stain DNA (546 nm excitation from a 100 watt mercury bulb; emission monitored using a 580 nm reflector and 590 bandpass filter)....you may also consult the following literature (Olive, P. L., & Banáth, J. P. 2006. The comet assay: a method to measure DNA damage in individual cells. Nature protocols, 1(1), 23).