MEREDITH VIEIRA is praying an experimental drug will save her husband, whose health continues to deteriorate from his decades-long struggle with multiple sclerosis, a source says.

Ailing Richard Cohen, 65, is legally blind and gets around with a cane, but Meredith, 59, says he’ll soon enter a clinical trial for a therapy using his own stem cells.

The treatment “has not been done with MS be­fore,” she recently told Bravo talk-show host Andy Cohen.

“Fingers crossed that it will be successful and maybe at least it will stop the illness at this point.”

A source close to the valiant TV veteran told The ENQUIRER: “Meredith is desperate to prolong Richard’s life. She’s watched him struggle for so many years, taking medications that haven’t helped.

“It’s been difficult for her. She felt helpless.”

Cohen was diagnosed with MS at the age of 25. Despite that, he went on to an Emmy-winning career as a TV news producer and fathered three children with Meredith.

But the incurable disease, which attacks the body’s cen­tral nervous system, continued its relentless assault, af­fecting his vocal cords, arms and legs. He’s also successfully battled two bouts with colon cancer.

“Meredith has always put on a brave front with Richard and their kids,” said the source. “She never complains, but she sees Richard’s health getting worse every day and she’s terrified that he’ll die if doctors don’t find something to help him soon. “She’s praying this experimental treatment works!”