Lomas admitted they were far from their best as substitute David Robertson headed an equaliser in the second minute of injury time to extend St Johnstone's unbeaten run to eight matches and move them within two points of SPL leaders Celtic.
But the Saints boss impressed with his side's determination to fight to the end after Billy McKay had opened the scoring and Andrew Shinnie missed a penalty for Inverness.
Lomas said: "The boys stuck at it, so all credit to them because we weren't great.
"We probably had the better chances in the first half, but it's important in a game that's tight to take those chances.
"However, I'm delighted with the result because we didn't play well, but give Inverness credit.
"They watched us and had us sussed out before the game. We needed a Plan B, but even that wasn't good enough."