Blair Underwood is starring in a new drama on NBC called "Ironside," which follows a parapalegic NYPD detective. Underwood’s casting for the role was controversial all on its own since he does not have a physical disability that requires him to use a wheelchair. But since the show has aired, it’s shed a new light on the way that disability appears on screen and the challenges facing actors who have physical disabilities.

There are only six disabled primetime characters on television, according to a report from GLAAD. Nearly 20 percent of people in America live with some form of physical disability, but fewer than two percent of roles in TV and film feature any characters who are physically disabled. Those characters have most often been portrayed in science fiction films like X-Men, and even then the idea is that someone’s physical disability is a gateway for another extrordinary superpower. According to a new documentary called CinemAbility looks at how the portrayal of disability on screen has changed over time. 

It’s a discussion that’s slowly gaining more traction. Blair Underwood has said in interviews that the role is especially meaningful to him because his mother, Marilyn, is in a wheelchair as a result of her battle with multiple schlerosis.