Just as Visine "gets the red out®" of irritated eyes, it provides temporary redness removal in acne in lieu of cosmetic camouflage. It takes just a few minutes to work but lasts up to six hours, especially when using Visine L.R.®.
As ginseng states above, Visine's active ingredient is either Tetrahydozoline-, Oxymetazoline-, or Naphazoline HCl. Since this main ingredient acts as a vasoconstrictor, it constricts blood vessels as well as skin tissue, reducing swelling. Applying it to the eye contracts the tissue around it, producing an extremely wide-eyed appearance. To minimize disparity, Visine can applied to both eyes even if only one is affected with redness or irritation. As with other eye drops, it may be easier to apply near the corner of the eye rather than plonking from above.
In emergency situations of having to store contact lenses overnight without the presence of saline solution, some Visine in a shot glass or a small container works well, but is not recommended for regular practice. The solution contains preservatives which may build up and damage lenses in the long run.
The Vaults of Erowid1 recommends consuming a ratio of 125 mL Visine/L water to pass a urine drug test after doing marijuana or hashish. However, Visine laden urine samples may seem suspicious in EMIT® tests in their inability to foam.2
2Testing Info. http://www.passitkit.com/testing.htm