Why do many Roman statues not have pupils in the eyes?

Answer 1

Roman statues were often heavily painted and so pupils would have been painted on the eyeballs. Later in the Empire under Emperor Hadrian, pupil carving was started to be used in practice. Most statues and portraiture after Hadrian had carved pupils

Answer 2

Classical Roman statues were often created with eyes that lacked pupils to give the figures a sense of timelessness and idealization. The absence of pupils in the eyes was a deliberate artistic choice to convey a sense of divine or noble presence rather than individualized human characteristics. This stylistic convention was influenced by the ancient Greeks and continued in Roman art to emphasize the eternal qualities of beauty and perfection.