Examples where “vision” (optasia) denotes a physical and supernatural event abound. In the New Testament, it is more often physical than not, where the term (optasia) is used these five times in total:
• Lk 1:22 applies it to Zacharais’ encounter with an angel physically next to the alter of incense.
• Lk 24:23 applies it to the women’s seeing the angels physically standing at the empty tomb.
• Acts 1:3 applies it (a cognate: optanomai) to Jesus presenting himself alive over 40 days, “with many convincing proofs” in a context where the author was making clear Jesus physically interacted with them.
• [Acts 26:19 is the verse under consideration.]
• 2 Cor 12:1 does not say whether the visions were intra-mental or extra-mental.1
Given that this vision (optasia) is a reference to Jesus's appearing, it is also--inevitably--a physical appearince since the author of Acts is clear in reporting that Paul said it was physical. He said in the immediate context that the light shine all around them and that “we had all fallen to the ground” (in verse 13). This is relevant because, if Paul (and the author of Acts) are competent users of the Greek, then we can expect that a physical appearance like this can be properly called an optasia.