满眼 is a noun that describes a scene or emotion that fills your eyes — a beautiful view that stretches before you, or tears that well up. It often appears in verb-like patterns such as 满眼是泪 ('eyes full of tears') or 满眼都是风景 ('the view fills the eyes'). Although the POS is noun, the word is frequently used in descriptive phrases where it functions adverbially or as part of a predicate.