Johansson gave Washington a 1-0 lead on a power-play goal at 3:39 of the first period. Strome passed into the slot for Johansson, whose shot deflected off Vegas defenseman Alex Martinez's stick and over Thompson's shoulder.
Eichel tied it 1-1 on the power play at 18:55 when he beat Lindgren with a low shot from the top of the right circle.
The Capitals took a 2-1 lead at 1:01 of the second period when van Riemsdyk got the puck off a face-off win by Strome and scored from the left point. It was van Riemsdyk's first goal in 43 games dating to Jan. 28 against the Dallas Stars.
Capitals forward Beck Malenstyn left the game with an upper-body injury after blocking a shot in the first, and Laviolette said he was being evaluated. Washington was already without injured forwards Nicklas Backstrom (hip), Tom Wilson (lower body), Carl Hagelin (hip, eye), Connor Brown (lower body) and T.J. Oshie (lower body).
"It's definitely hurting us a little bit," Johansson said. "We're missing some good, key pieces to this team. But there's no excuse. We battled hard and we think we played two good games, but unfortunately we couldn't come out with more than two points."
NOTES: Pietrangelo (397) passed Mark Giordano of the Toronto Maple Leafs (395) for the ninth most assists among active defensemen. … Eichel has 12 points (five goals, seven assists) in 11 games this season. … Golden Knights center Chandler Stephenson won 9 of 11 face-offs (82 percent). … Vegas is 7-2-0 against Washington in the regular season and has won the past four games between the teams. … Alex Ovechkin had an assist for the Capitals but remained at 785 goals, one behind Gordie Howe's NHL record for the most for one team (Detroit Red Wings). He was held to one shot on goal. … Washington was without defenseman John Carlson (lower body) for a second straight game. He is day to day.