I almost submitted a tag alias request for this, because the two tags appear to be used for the same thing in practice. But I realized that there is actually a possible distinction between the two. Ideally, red_glasses should probably be for glasses with red lenses, while red-framed_glasses would apply to the frames. Currently, there are only a few images with red-tinted glasses, and both tags are used for red frames. The version without "-framed" is much less used, but e.g. kuriyama_mirai's wiki page links to it.
One possible solution is to add a tag such as red-tinted_glasses. This would make the distinction between the two clearer. Then red_glasses could be aliased to one of the two or just deleted.