Small hint: Click on the trigger plates; you can get a fairly good idea of where you need the eyes from this alone.
Another, slightly bigger hint: Take good stock of the force arrows, as they dictate where you'll be able to move before the eyes will hop off and no longer stand on the trigger plates. If you have to, remind yourself of how arrows work. (For example: A force arrow pointing north [up] will let you go east and west as well as in a northerly direction [north-east, north, and north-west], but not in a southernly direction [south-east, south, or south-west].)
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×Get the eyes in three diagonal positions: First is top-left, bottom-right; second is bottom-left, top-right; and third is top-left and bottom-right again. After achieving each position with two eyes, you should be able to immediately kill one of the three 'hidden' eyes.