The nine- to 12-hour time difference between Sochi, Russia, and the U.S. have tamped down audience levels, in part, because most viewers know the outcome of key competitions long before NBC's prime-time broadcasts begin.
On Sunday night, NBC attracted 21.3 million viewers for its prime-time program, which showcased the breakout performance of American ice dancers Charlie White and Meryl Davis.
Sunday's audience totals represented an 8% decline from the same night during the Vancouver Olympics, when many of the contests aired live.
Through Sunday, the Sochi Olympics have mustered a 6.1 rating in the 18-to-49 age demographic, which is a 14% decline from Vancouver. The Olympics have averaged 23.2 million viewers in prime time, down 11% from Vancouver.
On a conference call Monday with journalists, Costas said he spent most of the last few days holed up in his darkened hotel room in Sochi.
Costas said he ventured out to a balcony that overlooks the Black Sea to get some fresh air. He also went to the hotel restaurant a few times.
Costas wasn't completely out of the loop. He said he followed the Olympics coverage after NBC Sports Group Chairman Mark Lazarus made special arrangements to provide the NBC feed to Costas' hotel room.
Although his pinkeye turned into something of an eyesore for viewers, he said it was the light sensitivity and blurriness that drove him from his longtime anchor role. Costas said his eyes were still red, but he no longer has the sensitivity that was aggravated by the bright TV lights.
"On the injury list of 1 to 10, this is now at about a 2,” Costas said.
Matt Lauer and Meredith Vieira filled in for Costas while he was out.
NBCUniversal and advertisers headed into the Sochi Olympics with reasonable ratings expectations because of the time difference. Some observers also have pointed to the less than spectacular showings for some heavily promoted athletes as another factor contributing to the lower audience totals.
“Would it be nice to have another gold medal here or there? Sure, but that's always the case in any Olympics," said NBC Olympics executive producer Jim Bell. Still, he said, "We couldn't be happier with how things are going."
NBCUniversal also has used the Olympics to raise awareness for its NBC Sports Network, which has seen its ratings soar. The cable channel broadcast Saturday's thrilling hockey match between the U.S. and Russia.