DVI stands for "digital visual interface". DVI cables are most commonly used to transmit video data from older PCs to older monitors (HDMI cables are a more advanced replacement that transmit audio data as well as video, unlike DVI cables). ...
Because it sends only sound, an optical audio cable is usually used with a video-only cable, such as DVI (Digital Visual Interface) or S-video. So, what's the catch? Well, optical cables tend to be somewhat brittle, and the plastic ones are not as lossless as their glass counterparts...