I don't think it's an idiom -- at least, not one that is used very much. It does, however, appear in poetry.
Forugh Farrokhzad, born in Teheran in 1935, wrote a poem called "Another Birth", in which the following lines appear:
My lips your kisses prize
Your lips are the temple of my eyes.
This was translated from the original Persian; it may well be an idiom in Persian, but I couldn't say. The poem, incidentally, is available
on this page.
In context, it would seem that the phrase "temple of my eyes" indicates something the eyes want to worship, i.e. something that is beautiful to look at.
The phrase also appears in the English translation of a poem called
You Are Peace by Friedrich Rückert:
The temple of my eyes
Is illumined
Only by your radiance,
Oh fill it completely!
The phrase actually translates the German "Augenzelt", which means literally "eye-tent". That could be a specific tent -- the tabernacle, the tent which housed the Ark of the Covenant, the most holy object the ancient Israelites had, before the temple was built -- a kind of temporary temple, in other words. The usual English translation is probably misleading, and it probably refers to the eyes themselves. It's worth noting that Rückert is not regarded as a good poet, and sometimes chose strange words because he had to make his poems rhyme.
idiom meaning 
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