This item seems strictly worse than the staring octopus eye (same equipment slot, same requirement, same bonus, not significantly easier to make, but gives -7 Strength), so I figured using it must grant a special technique or have some other benefit. So far, using it underwater with Ocean Sight and Burning Vision going has done nothing special vs. ruins octopus, foreign shark, or deep hunter even when I use eye-related techniques like Evil Eye and Withering Gaze.
Toxic Octopus Eye / Discussion
This is the discussion related to the wiki page Toxic Octopus Eye.