It does not invalidate his fast, even if he finds the taste of kohl in his throat or its color in his mucus or saliva, according to the more correct opinion, and it is not disliked for him; because the eye is not one of the considered openings, and what breaks the fast is what enters through the considered openings. It was narrated from Anas ibn Malik, may Allah be pleased with him, that a man came to the Prophet, peace be upon him, and said: "My eye is bothering me. Should I use kohl while I am fasting?" He said: "Yes." This is found in Jami' al-Tirmidhi 3: 105; and because what reaches the throat from the eye through using kohl only reaches it via the inside of the nose, and the passage from the eye to the nose is small and hidden, it is treated like pores, so what reaches the throat is excused: like dust and smoke that enters his throat, as mentioned in the rules of what breaks the fast by Muhammad Rafi' al-Othmani, p. 59. And see: Tanweer al-Absar and Rad al-Mukhtar 2: 98.