What is the ruling in Islam on putting eye drops during the daytime in Ramadan?

Scholars have differed on whether eye drops invalidate the fast. The Malikis and Hanbalis held that they invalidate it if they reach the throat, while the Hanafis and a group of scholars held that they do not invalidate it. The preponderant opinion is that they do not invalidate the fast. It is preferable to delay using them until night or to use a type whose taste does not reach the throat. If the taste does reach, one should spit it out.