By 2022 residents of Singapore won't be required to show a passport when they return home from another country. Instead, a scanner will compare their face and iris pattern to a matching record in a database. If the scan fails, they can use a fingerprint, also in the database.
From Today Online:
Since 2017, citizens and permanent residents have automatically had their facial and iris biometrics enrolled when they collected their new passport or IC.
ICA said that about 70 percent of Singapore citizens aged six and above and who hold a valid passport already have their iris and facial biometrics enrolled.
The Home Team Science and Technology Agency (HTX) — which collaborated with ICA to roll out the scanning system — said in a statement that iris patterns have a higher degree of variation and uniqueness as compared to fingerprints, and are therefore "more robust and reliable."