Ci, którzy mają krople do oczu, często noszą je w torbie przez cały dzień.

Together, Ci, którzy means those who.

They are doing two different jobs:

• Ci = those
• którzy = who

So Polish builds this idea as those, who..., where którzy introduces the relative clause.

Both forms are masculine-personal plural, which is the normal form for a group of people that is male or mixed. If you were talking about a group of women only, you would usually say:

• Te, które...

Because Polish normally uses a comma before a clause introduced by words like który, która, którzy, które.

So:

• Ci, którzy mają...

is standard punctuation in Polish.

This is different from English, where those who have... usually has no comma.

Because the subject is plural: Ci, którzy... = those who...

So both verbs must also be plural:

• mają = they have
• noszą = they carry / they wear / they keep with them

These are both 3rd person plural present-tense forms.

This is the normal Polish expression for eye drops.

• krople = drops
• do oczu literally means for the eyes or for use in the eyes

In Polish, do often means for / for use with / intended for, especially in product names and set phrases.

Compare:

• pasta do zębów = toothpaste
• krem do rąk = hand cream
• krople do oczu = eye drops

So this is not a word-for-word copy of English structure; it is simply the standard Polish way to say it.

Because the preposition do takes the genitive case.

The basic plural form is:

• oczy = eyes

But after do, it changes to genitive plural:

• do oczu

This form is also a bit irregular, because the noun oko has an unusual plural pattern:

• singular: oko
• plural: oczy
• genitive plural: oczu

So krople do oczu is grammatically required.

Je refers back to krople.

Since krople is a plural noun, the object pronoun is also plural:

• krople → je

Here je means them.

So:

• noszą je = they carry them

Even though English speakers may sometimes think of eye drops as one product, in Polish krople is grammatically plural, so je is the natural pronoun.

Because the preposition w meaning in takes the locative case when it refers to location.

The basic noun is:

• torba = bag

After w, it becomes:

• w torbie = in a bag / in the bag

So this is a case ending change:

• torba → torbie

Because Polish often leaves out possessive words like his, her, their, own when the meaning is already obvious from context.

So:

• noszą je w torbie = they carry them in a bag / in their bag

If you say:

• w swojej torbie

that adds emphasis to their own bag, especially if you want to contrast it with someone else’s bag.

So the shorter version is perfectly natural.

This phrase means for the whole day or all day long.

The preposition przez is often used to express duration of time, and it takes the accusative case.

So:

• przez
  • cały dzień

Here:

• cały = whole / entire
• dzień = day

Together:

• przez cały dzień = throughout the whole day

You can also hear simply cały dzień in Polish, but przez cały dzień clearly emphasizes duration.

Because nosić and nieść are related but used differently.

• nosić = to carry regularly, habitually, or for some time
• nieść = to be carrying something right now, in one specific act of carrying

In this sentence, the idea is habitual or extended:

• they often carry them
• they keep them in a bag for the whole day

So noszą is the right choice.

If you said niosą, it would sound more like they are carrying them right now.

Yes. Polish word order is more flexible than English word order.

The given sentence is natural:

• Ci, którzy mają krople do oczu, często noszą je w torbie przez cały dzień.

But you could also say:

• Ci, którzy mają krople do oczu, często je noszą w torbie przez cały dzień.

That also sounds very natural.

Changing the order usually changes emphasis, not the core meaning. Polish often moves words like często and short pronouns like je around more freely than English does.

Yes, in this expression krople do oczu is normally plural.

That is because krople literally means drops, and the medicine is commonly named that way in Polish.

If you specifically want to talk about the container, you would use a different noun, for example:

• butelka kropli do oczu = a bottle of eye drops

So in the sentence, the grammar follows the noun krople, which is why you get plural agreement and the pronoun je.