Retinal scan
From Memory Alpha, the free Star Trek reference
A retinal scan or retinal print is a security method by which individuals are identified when accessing critical or secured information. Retinal scans were in use, at least on Earth, since the early 21st century and were still used in the 24th century, although voiceprint access was more common.
The storage lockers in the assay office aboard Deep Space 9 were secured by a retinal print of a Cardassian MK-12 scanner. (DS9: "Q-Less")
In 2369, Kobliad Security officer Ty Kajada asked Doctor Julian Bashir if he did a retinal imaging scan of Rao Vantika's dead body to confirm that there was no residual activity in his visual cortex. (DS9: "The Passenger")
Major Kira Nerys personnel file featured both a retinal scan and a voiceprint in addition to a psychiatric profile and a holopicture. (DS9: "Meridian")
In the 2020s, SafeTech provided a retinal scan service for the United States of America government on Channel 178. (DS9: "Past Tense, Part I")
In 2370, Miles O'Brien was able to piece together data fragments of Vedek Bareil's retinal scan taken when he sealed a set of incriminating communications logs. (DS9: "The Collaborator")
