Senza gli occhiali, non vedo nulla.

Vedo is the 1st person singular present tense of vedere (to see).

• io vedo = I see
• tu vedi = you see
• lui/lei vede = he/she sees

Italian often drops the subject pronoun when it is clear from the verb ending, so (io) vedo naturally means I see.

Yes, nulla means nothing, but standard Italian usually uses negative concord. That means a negative word is often used together with non.

So:

• non vedo nulla = literally not I-see nothing
• natural meaning: I see nothing

This is normal Italian grammar, not a double negative in the English sense.

Compare:

• Non ho niente = I have nothing
• Non conosco nessuno = I know nobody

In this sentence, yes, they are basically interchangeable.

• Non vedo nulla
• Non vedo niente

Both mean I see nothing / I can’t see anything.

A small nuance:

• niente is usually more common in everyday speech
• nulla can sound a little more formal or literary in some contexts

But in a simple sentence like this, both are perfectly normal.

Because occhiali is a masculine plural noun that begins with a vowel sound, and the masculine plural definite article used before vowels is gli.

Compare:

• il libro → i libri
• l’occhio → gli occhi
• l’occhiale → gli occhiali

So:

• singular: l’occhiale
• plural: gli occhiali

That is why you get gli occhiali.

Italian normally uses occhiali in the plural to mean glasses or eyeglasses, just like English usually says glasses rather than a glass when talking about something you wear on your face.

There is a singular form, occhiale, but it usually refers to:

• a single lens or eyepiece
• one part of a pair of glasses
• or it appears in technical/specialized contexts

In everyday Italian, if you mean the thing you wear to see better, occhiali is the normal word.

Yes, you can say both, but the nuance is a little different.

• senza gli occhiali = without the glasses, often understood as without my/the usual glasses
• senza occhiali = without glasses, more general

In real life, when the glasses are already understood from context, Italian often uses the definite article:

• Non trovo gli occhiali = I can’t find my glasses
• Senza gli occhiali, non vedo nulla = Without my/the glasses, I can’t see anything

So the article does not always mean a very specific the in the English sense; it can also refer to something obvious from the situation.

Because Italian often omits the possessive when ownership is obvious from context, especially with personal items, clothing, and things closely associated with a person.

So:

• Mi sono tolto gli occhiali often means I took off my glasses
• Senza gli occhiali, non vedo nulla naturally suggests without my glasses

If you want to emphasize ownership, you can say:

• Senza i miei occhiali, non vedo nulla

But it is not necessary in ordinary speech.

The comma is not strictly necessary, but it is very natural when senza gli occhiali is placed first for emphasis or as an introductory phrase.

So all of these are possible:

• Senza gli occhiali, non vedo nulla.
• Senza gli occhiali non vedo nulla.
• Non vedo nulla senza gli occhiali.

They all mean essentially the same thing.

The version with senza gli occhiali first gives a slight feeling of: As for without glasses... I see nothing.

Gli is one of the trickier Italian sounds for English speakers.

A rough guide:

• it is not pronounced like English glee
• it is a soft sound similar to the lli in some pronunciations of million, but smoother and more clearly one sound

In careful Italian, gli occhiali sounds roughly like:

• lyi ok-KYA-lee

That is only an approximation, but it helps.

A few pronunciation notes:

• gli = a special Italian sound
• occhiali has stress on -a-: oc-CHIA-li
• ch before i or e is a hard k sound, so occhiali begins with ok-

Yes. In everyday Italian, people often say:

• Senza gli occhiali, non ci vedo.

This means something like:

• Without glasses, I can’t see
• Without glasses, I can’t see properly

The ci here is part of the idiomatic expression vederci, which often refers to one’s ability to see in general.

So:

• non vedo nulla = I see nothing
• non ci vedo = I can’t see / I’m unable to see well

Both are natural, but the original sentence is more explicit and stronger.