Donald MacKenzie, who was released from prison last October after serving three years for the 21 million fraud, was trying to register as a student in his new chosen profession.
But the General Optical Council (GOC) in London has ruled that his offences involved "startling dishonesty" which could damage public confidence in opticians.
The 48-year-old had already seen his application to the GOC to register as a student dispensing optician refused, sparking his appeal against the decision.
Now this appeal has also been rejected, leaving MacKenzie with the option of challenging it in the Court of Session in Scotland within the next 28 days.
MacKenzie – who was named Royal Bank of Scotland business manager of the year three years in a row – set up false loans worth millions over a five-year period.
While claiming he never kept any of the missing cash, MacKenzie was jailed in 2006 and, a year later, was ordered to pay back 63,000 he made in increased bank bonuses under the Proceeds of Crime Act.
Dismissing his appeal to become a student dispensing optician, Lady Margaret Wall, panel chair of the Registration Appeals Committee, said: "The papers before the committee show offences of startling dishonesty involving sums which are barely credible over a period of some four-and-a-half years.
"They also show unusual features which were very clearly set out in mitigation, in the judge's sentencing remarks and in his report to the appellate court.
"The appellant has been a model prisoner who has been assessed as very unlikely to re-offend. Moreover, he has been supported in his aspiration by a member of this profession."
Lady Wall said that support for MacKenzie's application was "undoubtedly impressive".
But she said that MacKenzie had made it clear that he would like to begin training in September, but his jail term licence did not expire until February 2013.
She added: "Trustworthiness and honesty lie at the heart of what it is to be a professional.
"The committee is deeply troubled by what it thinks is the inevitable reaction of any honest member of the public confronted by these facts and indeed by the reaction of any honest patient.
"Whilst they and the committee would, and do, applaud the attempts of Mr MacKenzie to turn round his life and to respond to imprisonment as he has done, they would be affronted by the notion that a man still on licence for such serious offences could embark on student membership of a profession."
MacKenzie, who had been employed as a business manager at a branch in Princes Street, pleaded guilty to embezzling the 21m having accessed the money through the bank's loan system by setting up false accounts in the names of fictitious customers.
MacKenzie was caught after the RBS introduced a new computer system. The bank found that suspect data had been put in by MacKenzie and traced a series of "highly suspicious" transactions.
He worked at a supermarket just prior to going to jail.