Minecraft Bedrock Testfor Command

I play on the Bedrock edition and I'm looking for an easy way to find and count Eyes of Ender inside portal frames. My initial thought was to use testfor but I can't seem to get the coding right. This is what I tired,

/testfor @e[type=Item,name=ender_eye,r=50]

But it just says "No selector with that name", is there a difference between eyes on the ground and eyes already placed in the portal frame? Am I just looking for the wrong name? Anyone with more knowledge on this subject?

As Fabian said, end portal frames simply have a different data value if they have an eye of ender in them or not. Data values 0 to 3 have no eye of ender and are the directions south, west, north, and east. Data values 4 to 7 are the ones with the eye of ender (same directions).

You need to use testforblock:

testforblock <x> <y> <z> end_portal_frame <data value>

You will need to have 4 commands to test for data values 4, 5, 6, and 7 to match all directions that the end portal frame can face.