Q: Is it permissible to use contact lens solution while fasting or does it break one's fast.
It is permissible to wear contacts and use contact lens solution while fasting. This is because even if the lens solution were to reach to one's throat somehow it is not food or drink nor is it similar to food or drink, in that it does not nourish.
For more info see the this article. It is also pasted here for ease of reference.
And God knows best.
Can we wear lens while fasting? Note that we have to put lubricant every four hour?
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We have already issued a Fatwa clarifying that it is permissible to wear contact lenses while fasting and that wearing them does not invalidate the fast. If wearing them necessitates using a lubricant as you mentioned, then if you mean that this lubricant is put in the eyes, it takes the ruling of the eye drops. The scholars differed in opinion about eye drops, some are of the view that it invalidates the fast while others are not of this opinion.
The Fiqh Encyclopedia reads: "Putting eye drops, oiling the eyelids, and putting medicine with oil in the eye, none of this invalidates the fast even if one finds its taste in his throat. This is the correct opinion according to the Hanafi School of jurisprudence, and the opinion of the Shaafi'ee School appears to correspond with the Hanafi view. However, the Maaliki and Hanbali Schools of jurisprudence are of the view that putting eye drops invalidates fasting if these drops reach the throat, as the eye is an inlet to the throat even if it is not a usual one."
In our view in Islamweb, we consider the first opinion - which is that putting eye drops does not invalidate the fast - to be the preponderant one, and this is the opinion chosen by Shaykh Al-Islam Ibn Taymiyyah .
This is in case the drops or the solution which you mentioned in the question reaches the throat, otherwise if it does not reach the throat, it does not break the fast even according to the Schools which are of the view that fasting is invalidated if the eye drops reach the throat.
For instance, 'Olaysh from the Maaliki School of jurisprudence, said: "One should not apply Kohl eyeliner (to his/her eye) and should not put oil in his/her ear unless he/she knows that it does not reach his/her throat, and if one applies the Kohl or any other substance, it is permissible if this does not reach the throat."
To conclude, it is permissible to put the solution in the eye when wearing the contact lenses and this does not invalidate the fast according to the most preponderant opinion of the scholars .
Allaah Knows best.