'A’isha (RAA) narrated, The Messenger of Allah (ﷺ) applied kohl to his eyes while he was fasting.’ Related by Ibn Majah with a weak chain of narrators. According to At-Tirmidhi, nothing authentic has been related from the Prophet (ﷺ) concerning this issue, i.e. applying kohl, eye drops etc. to the eye while fasting.

وَعَنْ عَائِشَةَ رَضِيَ اَللَّهُ عَنْهَا, { أَنَّ اَلنَّبِيَّ ‏- صلى الله عليه وسلم ‏-اِكْتَحَلَ فِي رَمَضَانَ, وَهُوَ صَائِمٌ } رَوَاهُ اِبْنُ مَاجَهْ بِإِسْنَادٍ ضَعِيفٍ [1]‏ .‏ قَالَ اَلتِّرْمِذِيُّ: لَا يَصِحُّ فِيهِ شَيْءٌ [2]‏ .‏