Various translations are clearly possible depending on the context and tone of the source. I have used an imperative phrase, but it might also be expressed as a rather more neutral description, i.e., "the eye concentrates on [or 'follows'] the [opponent's] stance." The phrase "目随势注" seems to refer to a static situation, in contrast to the dynamic, "手眼相随" "hand and eye follow each other," in which one watches for motion. An explanation from the indicated website: "动作时“手眼相随”，以眼表达出动作的意向。静止时“目随势注”，以眼表达出观敌变化伺机待动的神态"