Sadly, I do not know the answer to your very interesting question. However, I do know where you should look, if you do not get a suitable answer here:
It's a contentious question. Traditionally the Byzantine Iconoclasm was thought to be very much influenced by the Islamic rejection of icons. Historians like Toynbee (and also I think Bury and Runciman) wrote that the military victories of the Muslims convinced the Byzantines that their attitude towards icons was wrong and thus the Iconoclasm started.
Modern historians more often point to theological and social motivations behind the iconoclasm (although the Arab conquests indirectly contributed to these).