olemus
silmapõhi, silmamuna seinakihi seesmisim kiht;
reetina soontevõrgu muster on füüsiline biomeetrik

piltlikult
https://duckduckgo.com/?q=retina&t=h_&iax=images&ia=images

ülevaateid
https://en.wikipedia.org/wiki/Retina

https://en.wikipedia.org/wiki/Retinal_scan

https://www.axonwireless.com/biometric-iris-and-retina-scanner-device/

https://biometrictoday.com/differences-between-iris-recognition-and-retina-scanning/