I've heard anecdotal evidence that UV can cause blindness in lighter Corn morphs as they lack the dark pigment that would protect them from damage. Kind of like putting a redheaded person out in the midday sun without any sunblock. However, this was just an observation from someone who ran a reptile rescue, so I don't think it's ever been proven (she'd taken in blind Corns over the years and they had mainly been paler morphs kept under UV).
Corns don't need UV, because Corns aren't a basking species and have never developed a dependency on it. This is different to Beardies, which will suffer major health problems without it.
I've never used it - these days I don't have any form of artifical light in my vivs and my lot seem to do OK. As with most things Corn-y, there are no hard-and-fast rules, but generally most folks don't seem to use UV with their Corns and I can't remember ever having seen health problems attributed to this.
There are other sorts of light you can use if you want it for your benefit, just to make vivs appear more attractive. Sure others will be along to advise in due course.