The Briton, who had an operation to remove fluid from the brain after collapsing two days before the the Dubai Desert Classic, said he felt fine and was "back in business", but he is troubled by short-term memory loss.
"I had to ask the caddie the names of my playing partners in the pro- am soon after they told me them because I tend to forget things from five minutes ago," he said. "But I got the thinking side of my game right, the thing that I was most worried I'd forgotten."
Carter had birdies at the 10th, 13th and 17th to finish alongside Britain's Paul Broadhurst and Stuart Cage, and the Dutchman Rolf Muntz. They trail New Zealand's Stephen Scahill.