Andrew Gosden vanished from Doncaster in September 2007 and the mystery surrounding his disappearance has been one of the most high-profile missing person cases of the last 20 years.
South Yorkshire Police said the new picture is the first to show Andrew without glasses and detectives appealed to the missing man, or anyone who believes they may know him, to get in touch.
Andrew left his home in the Balby area of Doncaster on September 14 2007 and was seen heading down Littlemoor Lane, towards Westfield Park, at around 8.30am.
Around an hour later, he withdrew £200 from his bank account and boarded a London-bound train at Doncaster station.
Andrew was captured on CCTV at Kings Cross station at around 11.20am the same day.
A force spokesman said there have been many sightings of people bearing some resemblance to Andrew over the years but no positive sighting has ever been confirmed.
Andrew's father Kevin has now released more details about his son's appearance and traits on his blog.
When Andrew went missing, his vision was very poor and he needed strong lenses but the new picture shows him without glasses as he may now be using contact lenses.
Detective Inspector Andy Knowles, who has been overseeing the police investigation into Andrew's disappearance since 2017, said: "While this latest photograph may not seem to show much change, someone's face can look drastically different without glasses and therefore it's important that we share this photograph in case it helps jog someone's memory.
"Andrew has now been missing 12 years and his family are understandably desperate for any answers that may help them understand what happened to their loved one.
"Sharing specific features of Andrew's appearance and character is intended to help the public and reduce the number of generalised sightings we receive.
"We want you to study Kevin's blog closely and think hard about anyone in your lives who may have one or more of these traits.
"Anyone in your life who has an incomplete life history, anyone who might not have easy access to a bank account or a passport possibly, with the distinctive right ear markings that we know Andrew had - we'd be really keen to speak to those people."
Mr Knowles added: "I would also like to take this opportunity to once more appeal to Andrew directly.
"Andrew, know that you can contact us completely confidentially - let us know you are safe so we can reassure your family that you have come to no harm."
Anyone who believes they have information about Andrew is asked to contact South Yorkshire Police on 101, quoting incident number 161 of 13 September 2017, or Crimestoppers anonymously on 0800 555111.