This has happened before, they used to accept retest for several years, then they stopped and if you failed that was it your were done, then they started accepting them again.
When they would accept retest originally there were some recruiters that would have their candidates go to different eye docs until they passed, unfortunately they would often fail down the road. I was told that the number that failed, retested and passed, then failed after selection was enough to halt the retest, maybe that has happened again??