Мы оставим антибликовое покрытие, если только рецепт на очки не изменят.

Оставим is the 1st person plural future form of the perfective verb оставить.

• мы оставим = we will leave / we will keep
• Perfective aspect presents the action as a completed decision/result.

Here that fits well, because the speaker is talking about a one-time decision: we’ll keep the anti-glare coating.

If you used an imperfective form, the meaning would change. For example, будем оставлять would sound more like a repeated or ongoing action, which does not fit this context.

Yes. Оставить literally often means to leave, but in many contexts it naturally means to leave something as it is, which English often expresses as keep.

So here:

• Мы оставим антибликовое покрытие
  literally: We will leave the anti-glare coating
• natural English: We’ll keep the anti-glare coating

This is very common in Russian: a verb may be translated differently depending on what sounds natural in English.

In this sentence, если только introduces an exception condition and is best understood as unless.

So:

• если только рецепт на очки не изменят
  = unless they change the glasses prescription

Depending on context, если только can also mean something closer to if only or only if, but here the whole pattern если только ... не works like unless.

The не is part of the negative condition: if they do not change the prescription.

Word-for-word, the Russian structure is roughly:

• if only / if it’s just the case that they do not change the prescription

But idiomatic English normally says:

• unless they change the prescription

So the не is not random. It is the normal negation of изменят.

This is a very common Russian pattern. A 3rd person plural verb can be used with an unspecified human subject:

• изменят = they will change
• but they does not refer to specific named people

It means something like:

• someone will change it
• the doctor/optician/clinic will change it
• they’ll change it in the vague English sense

This is called an indefinite-personal use.

It can mean both recipe and prescription.

In medical and optical contexts, рецепт often means prescription:

• рецепт на очки = glasses prescription
• рецепт на линзы = contact lens prescription

So this is not about cooking at all. Russian uses the same word in both areas, and context tells you which meaning is intended.

Here на means for.

• рецепт на очки = a prescription for glasses

This is just the normal Russian pattern:

• рецепт на лекарство = prescription for medicine
• рецепт на очки = prescription for glasses

So на is the preposition required in this expression.

Because очки is normally a plural-only noun when it means glasses / spectacles, just like English glasses.

So Russian says:

• очки = glasses
• на очки = for glasses

You normally do not use a singular form to mean one pair of glasses.

They are both objects here, so they are in the accusative case. But their accusative forms happen to look the same as the nominative forms.

1. антибликовое покрытие
   This is a neuter inanimate singular noun phrase.
   For neuter inanimate nouns, nominative = accusative.

2. рецепт
   This is a masculine inanimate singular noun.
   For masculine inanimate nouns in the singular, nominative = accusative too.

So although the forms look unchanged, the case is still doing its job in the sentence.

No. It is the direct object.

The implied subject is an unspecified they:

• (они) не изменят рецепт на очки
• they will not change the glasses prescription

So:

• implied subject: they
• direct object: рецепт на очки

This is why изменят is plural even though рецепт is singular.

Yes, that is possible, and it would mean something like if the glasses prescription does not change.

Compare:

• если только рецепт на очки не изменят
  = unless they change the glasses prescription
  Focus: some people may change it.

• если рецепт на очки не изменится
  = if the glasses prescription doesn’t change
  Focus: the prescription itself remains the same.

So the original sentence uses a more human-centered wording, while не изменится is more neutral and event-centered.

Антибликовое is an adjective modifying покрытие.

• покрытие = coating
• антибликовое покрытие = anti-glare coating / anti-reflective coating

The adjective agrees with покрытие in:

• gender: neuter
• number: singular
• case: accusative (same form as nominative here)

So антибликовое has the ending that matches a neuter singular noun.