O's dominated the first half but paid the price for scoring just once when County were on the rack.
Orient's pressure told when Michael Raynes put through his own net but the visitors battled back and levelled on 56 minutes when Rob Clare headed home.
As both side's lost the plot defensively, John Mackie restored Orient's lead but County hit back immediately and Jermaine Easter headed his side back on terms within sixty seconds.
Orient, who went into the game unbeaten in ten league matches, made a lacklustre start but gradually moved through the gears after County skipper Matthew Hamshaw tested their nerve when he sent a free kick inches wide on nine minutes.
Orient were lucky not to be awarded to penalty when Shane Tudor appeared to be tripped in the box and, as the pressure started to mount on the visitors it came as no surprise when Justin Miller's ball in from the right found Jabo Ibehre and his shot deflected off luckless defender Raynes and looped over goalkeeper James Spencer.
O's were now in full flow and Miller headed wide from close range as a catalogue of chances fell their way.
Tudor twice and then Michael Simpson could have stretched Orient's lead before half time.
After the break Ibehre wasted a golden chance to add a second when he fired over from close range and it proved to be a costly miss.
Shortly afterwards Clare headed home unmarked at the far post from Hamshaw's free kick from the right.
The dangerous Ikeme went close to giving County the lead with a speculative overhead kick before O's defender Mackie popped up at the far post to drill home Matt Lockwood's free kick from the left.
Orient's joy lasted just 60 seconds as Easter superbly headed home Harpal Singh's excellent left wing cross.
After that the floodlight's dimmed and the lights went out on Orient's bid to stay top of the table as Lockwood and substitute Daryl McMahon had chances to win the game but failed to beat County keeper Spencer.