Explanation #1 (Rashi): We discuss eating.

Rebuttal #1 (and Explanation #2 - Ri): No, we discuss putting them on the eye. Our entire Sugya discusses this.

Rebuttal #2: If we discuss eating, how can Rav Sheshes forbid Gargira (rocket plant), since healthy people eat it? A Mishnah (109b) says that one may eat any food for Refu'ah [if healthy people eat it]!

Question (Ri): If so, why did Rav Yosef need to say that [the Isur of] Refu'ah does not apply to coriander, since it harms the eyes? All the more so it does not heal!

Answer (Ri): He means as follows. Refu'ah does not apply to it, i.e. some err and think that it heals. It does not heal. Rather, it harms the eyes!

It can be that it helps him in some way.

Explanation (R. Chananel): This is juice that they strain from watermelon innards, and they drink it in order to loosen the bowels.

Explanation: He means that one may strain from the innards, and they drink it in order to loosen the bowels, like we conclude, since it is eaten like this (without straining), he does not do anything (it is not considered Borer).

Distinction: [Straining] soft-boiled eggs is forbidden, for they are not properly eaten without straining.

Support: According to R. Chananel, it is fine that this was taught here, that we discuss Refu'ah.

Implied question: A Mishnah (below, 147a) teaches "one who bathes in cave water or in Mei Tiverya", and the Gemara infers that this is b'Di'eved, but not l'Chatchilah!

Answer #1: There we discuss one who bathes in the source [of the spring], similar to a bathhouse, but in the river is l'Chatchilah, like I explained above (39b DH v'Ha).

Answer #2 (Rav Nisim Gaon, in a hidden scroll): It taught "one who bathes", i.e. b'Di'eved, but not l'Chatchilah, due to cave water. However, in Mei Tiverya it is permitted even l'Chatchilah;

It taught Mei Tiverya only to teach about cave water, that it is hot, similar to Mei Tiverya.

The reason [why we are more lenient about Mei Tiverya] is because Mei Tiverya is exposed, but cave water is covered, like it says in Bava Kama (50b) that a cave has much hot air because it is covered. We are concerned lest he sweat. Therefore, l'Chatchilah it is forbidden.

Explanation (Riva): The reason is because they are constantly going back and forth, to here and to here, so they are like Zochalim (moving water). Therefore, they are Metaher through Zochalim, like other rivers;

However, they are not Mayim Chayim, for they do not flow, Therefore, it is more reasonable that the Torah called them "Mikveh" to disqualify them from Mayim Chayim.

Question: How do we compare this? The argument above refers to Refu'ah! (This is like Rav Nachman bar Yitzchak's rejection! Maharsha - Rav Nachman merely said that we could distinguish Taharah from Shabbos. Tosfos asks that they must be different, for all forbid in the Dead Sea, even though it is like other seas for Taharah! Kol Yehudah says that Rav Nachman asked only based on the verse. Tosfos asks from reasoning that there is no reason to compare them. Chidushei ha'Ran - the continuation of the Mishnah cited disqualifies salty water for Mei Chatas. R. Yochanan held that R. Yehudah holds that Yam ha'Gadol is a Mikveh, and Pasul for Mei Chatas, because it is salty. Therefore, one may not bathe in it, just like in Yam ha'Melech. Rav Nachman rejects this; it is a Gezeiras ha'Kasuv. It is not due to salt.)