From the end of the 9th century this is the mosaic above the Emperors Portal. Christ sits on a jewel studded throne. He holds a book with “Peace be to you all. I am the light of the world.” Thus, with the blessing hand upward, he is known as Pantocrator (Creator of the Universe). At his feet Leo VI. In medallions Maria and an angel.
I have been informed from a dependable source that iconoclasm was ended by Leo's "grandmother" Theodora. The same source wrote: The mosaic is depicting a scene which took place late in Leo's reign- he was denied entrance to the church because he took a fourth wife and he threw himself to the ground and wept. The Patriarch commissioned the mosaic and placed it above the imperial doors as a warning to future emperors.