Small-screen icon Bob Newhart (search) will stand tradition on its ear when he joins "ER" (search) tonight for a three-episode story arc.

"This is the first intentional dramatic TV role I've ever done," New-hart told The Post. "I thought it was quite courageous of them to think of me in terms of a dramatic role."

Newhart portrays Ben Hollander, a man suffering from macular degeneration (gradual loss of eyesight). Initially it seems Hollander's visit to the ER is simply a result of his mistakenly ingesting too much medicine - but Dr. Lewis (Sherry Stringfield) has other ideas.

"She suspects there's something more to it than just the dosage - she suspects he's trying to take his life," he said.

Newhart said the arc is a bit like a murder mystery, with a "does he or doesn't he?" ending. "ER" took great care in getting the details right. Newhart said one of the show's technical advisors "showed me how a person with macular degeneration would go around their apartment, where they know where certain things are, but it's a cross between being blind and not being blind," he said.

What also pleased Newhart was the opportunity to create a well-rounded older character.

"There are some real-life older people who don't want to extend their lives," he said, noting that one of the program's writers had based the story on the experiences of an older relative who "was a very bright woman and got cut off from her world."

"A lot of money is spent trying to keep people alive who don't necessarily want to be alive," Newhart said. "It's hard for me to picture. I can't imagine committing suicide but, then again, I'm not losing my eyesight and this guy is."

By no means has Newhart, 74, retired from his comedy roots. Recently seen in "Legally Blonde II," he plays "Papa Elf" in the holiday movie "Elf," (search) which also stars former "Saturday Night Live" cast member Will Ferrell (search).

Will fans buy into the funnyman of "The Bob NewhartShow" and sitcom "Newhart" playing a man contemplating taking his own life?

"It will be interesting to see how it's received," Newhart said. "Whether the people think of me as Bob Newhart, or Bob Newhart playing a guy with macular degeneration, or a guy with macular degeneration."