Caption wrap in lightbox

Is it possible to set the caption to wrap in the lightbox, so that it goes to a new line once it reaches the width of the image? Or at least to set a maximum width for the caption (say, 800px) so that it wraps to a new line when 800px width is exceeded, even if the image is only 500px wide?

Currently the caption continues to the right of the page and off of the screen rather than going to a new line if it is long enough (many of mine are).