Retinal scan

From Memory Alpha, the free Star Trek reference.

A retinal scan 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.

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 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")