The passage contrasts two ways of describing effects: an event occurring at the presence of a cause and an effect occurring through a cause. The former stresses divine creation on the occasion of an accustomed means; the latter may speak of the efficacy of means under divine power.
Classical Sunni theologians discuss these formulations in more than one way. The shared principle is not to grant created things efficacy that is autonomous of God.
The eye and light are ordinary conditions of sight. Whether the result is ascribed to the cause as an instrument or directly to divine creation is a distinct metaphysical question.
The meaning intended by “cause” must be established rather than inferred from the word alone.