A rare eye condition helped Leonardo da Vinci paint distance and depth of objects on flat surfaces with the accuracy which he became famous for, new research claims. Da Vinci, one of the world's most celebrated painters, had intermittent exotropia, a type of eye misalignment in which one eye turns outward, according to a study published in the journal JAMA Ophthalmology. "Looking at his work, I noticed the pronounced divergence of the eyes in all of his paintings," explained the study's author, Christopher Tyler, a research professor at City University of London and the Smith-Kettlewell Eye Research Institute in San Francisco. Click here to read the full story from CNN.