The scholars differed concerning eye drops and whether or not they break the fast.
The view favoured by Shaykh al-Islam Ibn Taymiyah and by Shaykh Ibn ‘Uthaymeen, is that they do not break the fast.
Shaykh Ibn ‘Uthaymeen said:
Shaykh al-Islam Ibn Taymiyah was of the view that kohl does not break the fast, not even if the taste of the kohl reaches the throat. He said, this is not called food or drink, and it is not like food or drink, and it does not have the same effect as food or drink. There is no saheeh hadeeth from the Prophet (peace and blessings of Allaah be upon him) which expressly indicates that kohl breaks the fast, and the basic principle is that it does not break the fast. An act of worship remains valid unless it is proven that it is invalidated. What he said is correct, even if a person can taste it in his throat. Based on the view favoured by Shaykh al-Islam, if a person puts drops in his eyes whilst fasting and tastes it in his throat, that does not break his fast.
Al-Sharh al-Mumti’, 6/382.