Learn Hardcore Greek: Φοράω γυαλιά όταν διαβάζω, γιατί αλλιώς τα μάτια μου δεν βλέπουν καθαρά. - I wear glasses when I read, because otherwise my eyes don’t see clearly.

Φοράω γυαλιά = “I wear glasses / I (usually) have glasses on.”
If you wanted to stress the moment of putting them on, you’d use something like βάζω τα γυαλιά μου (“I put my glasses on”). Here the sentence talks about a general habit when reading, so φοράω is the natural choice.

Why is γυαλιά in the plural? Is there a singular form?

In Greek, γυαλιά is almost always plural when it means “(eye)glasses.”

τα γυαλιά = “the glasses”
There is a singular το γυαλί meaning “glass” as a material or a pane of glass (e.g. a window), not eyeglasses. So when you talk about the thing you wear to see better, you use the plural γυαλιά.

Why is there no article before γυαλιά in φοράω γυαλιά?

Greek often omits the article with plural nouns when talking about something in a general or habitual way, especially with clothing or things you wear:

φοράω γυαλιά ≈ “I wear glasses (in general).”
If you say φοράω τα γυαλιά μου, you’re specifying particular glasses (my own pair, in a specific situation). Here the idea is “I (generally) wear glasses when I read,” so no article is needed.

What nuance does the present tense φοράω have here?

The present tense in Greek (here φοράω) usually expresses:

a present state (“I am wearing right now”), and/or
a habitual action (“I wear / I usually wear”).

In this sentence, combined with όταν διαβάζω, it clearly has a habitual meaning: “Whenever I read, I (typically) wear glasses.”

Why is όταν used, and not something like αν?

Όταν means “when” in the sense of “whenever/each time that,” referring to a time situation.

όταν διαβάζω = “when(ever) I read.”

Αν means “if,” introducing a condition rather than just a time.
You’d say αν διαβάζω only in specific conditional contexts, and it would usually sound odd for a simple routine like this. For ordinary “when I read” = “whenever I read,” όταν is the standard conjunction.

Why is διαβάζω also in the present, not a future or something else?

Greek often uses the present with όταν for general, repeated actions:

Όταν διαβάζω, φοράω γυαλιά. = “When(ever) I read, I wear glasses.”

If you talked about a specific future event, you could use the future:

Όταν θα διαβάζω για τις εξετάσεις, θα φοράω γυαλιά.
But for a general habit, present + present is normal and corresponds to English “when I read, I wear …”

How is γιατί functioning here, and how is it different from its “why” meaning?

Γιατί has two main uses in Greek:

As a question word: Γιατί; = “Why?”
As a conjunction: γιατί = “because.”

In your sentence, it’s the conjunction “because”:

… γιατί αλλιώς τα μάτια μου δεν βλέπουν καθαρά. = “… because otherwise my eyes don’t see clearly.”

You can tell it’s “because” because it doesn’t start a direct question and it follows a comma, introducing the reason.

What exactly does αλλιώς mean here?

Αλλιώς means “otherwise,” “in a different way,” or “or else.”
In this sentence:

γιατί αλλιώς τα μάτια μου δεν βλέπουν καθαρά
means “because otherwise my eyes don’t see clearly” = “if not / if I don’t wear glasses, then my eyes don’t see clearly.”

So αλλιώς is expressing the alternative situation: the way things are if the first clause doesn’t happen.

Why is it τα μάτια μου and not just μάτια μου?

Greek normally uses the definite article with body parts, even when a possessive pronoun (μου, “my”) is present:

το χέρι μου = “my hand”
τα μάτια μου = “my eyes”

Saying μάτια μου without the article is possible, but it’s more marked—often endearing or poetic (“my eyes!” as a term of affection). In neutral, everyday speech, τα μάτια μου is the default.

Why is μάτια plural, and what is the singular?

The noun is:

Singular: το μάτι = “eye”
Plural: τα μάτια = “eyes”

Since you naturally have two eyes, and we’re talking about eyesight in general, Greek uses the plural μάτια (“eyes”), just like English “my eyes don’t see clearly.”

Why is the verb βλέπουν in the third person plural?

Verbs in Greek must agree with their subject in person and number.
The subject in that clause is τα μάτια μου (“my eyes”), which is third person plural.
So the verb must also be third person plural:

αυτά βλέπουν → “they see”
τα μάτια μου βλέπουν → “my eyes see”

Hence δεν βλέπουν (“do not see”) is the correct form here.

Why is the negative δεν used and placed before βλέπουν?

Δεν is the standard negation particle used with indicative verbs (present, past, future) in Greek. It always comes directly before the verb:

βλέπουν → δεν βλέπουν (“they don’t see”)

The other negation particle, μη(ν), is used in different contexts (imperatives, subjunctive, certain fixed expressions). Since this is a straightforward indicative statement, δεν is the right choice and goes right before βλέπουν.

What is καθαρά grammatically, and how is it formed?

Καθαρά here is an adverb meaning “clearly.”
It comes from the adjective καθαρός (“clean, clear”):

καθαρός (masc.), καθαρή (fem.), καθαρό (neut.) → adjective
καθαρά → adverb (“in a clear way”)

So δεν βλέπουν καθαρά literally means “they don’t see in a clear way” = “they don’t see clearly.”

Is the word order γιατί αλλιώς τα μάτια μου δεν βλέπουν καθαρά fixed, or can it change?

Greek word order is fairly flexible. The given order is very natural, but you could also hear:

… γιατί τα μάτια μου αλλιώς δεν βλέπουν καθαρά.
… γιατί τα μάτια μου δεν βλέπουν καθαρά αλλιώς. (less common, more marked)

Placing αλλιώς near the beginning of the clause (γιατί αλλιώς …) nicely introduces the “otherwise / or else” scenario right away, so that order is especially natural here.