Issued January 6, 1996 by the Congregation for the Eastern Churches. The Vatican. Libreria Editrice Vaticana - 1996
107. Prayer facing the east
... 'For just as lightning comes from the east and is seen as far as the west, so will the coming of the Son of Man be' (Mt. 24:27). Waiting for him, we prostrate ourselves toward the east. It is an unwritten tradition, deriving from the Apostles."
This rich and fascinating interpretation also explains the reason for which the celebrant who presides in the liturgical celebration prays facing the east, just as the people who participate. It is not a question, as is often claimed, of presiding the celebration with the back turned to the people, but rather of guiding the people in pilgrimage toward the Kingdom, invoked in prayer until the return of the Lord.
Such practice, threatened in numerous Eastern Catholic Churches by a new and recent Latin influence, is thus of profound value and should be safeguarded as truly coherent with the Eastern liturgical spirituality.
(HT to The Hermeneutic of Continuity)