What is the significance of the alcor star in the Ursa Major constellation?

I read some time ago that the Alcor star (the star that sits next to the 2nd star along the Big Dippers handle) has some sort of significance for something but i can't remember what it is. Does anyone have any ideas?|||Mizar (The 2nd star) and Alcor (Binary pair) together are sometimes called the "Horse and Rider"





The significance could be the fact that the ability to resolve the two stars with the naked eye is often quoted as a test of eyesight.|||It's supposed to be a test of how good your vision is if you can see more than one star. It's sort of like how many stars you can see in the Pleiades star cluster. Even though there are hundreds of stars in this group, most people can't make out more than about seven of them.|||Alcor was considered by the Arabs to be an indication that your eeyesight was OK, as it is a less bright companion to Mizar.|||The ability to see Alcor separate from its close partner Mizar was a test of vision.|||It is a quadruple star...