The Immaculate Conception is based upon the idea that the Fall deprived Adam's descendants of original justice, and therefore left man condemned and subject to the devil.
Since St. Photius affirmed the Immaculate Conception before the doctrine was explicitly recognized in the West, it would be rather strange to blame it on Western theology.
That's strange since the Greek Orthodox website says the exact opposite.
PHOTIUS' ENCYCLICAL TO FIVE PATRIARCHS OF THE EAST (866) Patriarch Photius of Constantinople was an outstanding hierarch and leader who as a layman was elected patriarch by vote of the people and ecclesiastical authorities. He brought order to the Church and increased its missionary work, especially in Bulgaria. What became another major source of the teachings of the Church is the encyclical epistle of Photius sent to the Patriarchs of the East, with the consent of the Synod of Constantinople, protesting against the innovations of Pope Nicholas I of Rome: his interference in the affairs of the newly-converted nation of Bulgaria, the addition of the filioque phrase in the Nicene Creed, the issuing of the Pseudo-Isidorian Decrees and the Pseudo-Constantian Gift. This encyclical of Photius restated the correct teaching of the Nicene Creed, opposing the filioque phrase; correctly asserted the canonical jurisdictional order of administration of the Church; reaffirmed the correct teaching against the primacy of the pope, his infallibility, the riches of Christ and the saints, indulgences, purgatory, the Immaculate Conception of the Virgin Mary and her bodily assumption. All of these innovations of the West were among the factors which ultimately led to the Great Schism in 1054, setting the stage for the Protestant movement in 1517 as well. Photius' great encyclical restated and reaffirmed the orthodox teaching of the Undivided Church, and stands as a major source of Orthodox teaching.
What is important, gbcdoj, and what you Latins always seem to ignore, is that the Immaculate Conception or the Filioque were not accepted by the Church officially in the first millennium, regardless of what some individual fathers said at one time or another. Fathers do not make pronouncements for the whole church. Only the Ecumenical Councils do. Fathers speak for themselves; they are not inspired and infallible.
As far as the undivided Church was concerned, neither was the Pope the Patriarch, nor was there Immaculate Conception, nor Filioque, nor indulgencies, etc. no matter what some fathers said.