El óptico revisó las gafas.

Yes, el means the, and it is required here because óptico is being used as a specific noun: the optician.

In Spanish, you normally need an article with a common noun when you mean a specific person or thing:

• El óptico revisó las gafas. = The optician checked the glasses.

Compare that with profession after ser, where Spanish often drops the article:

• Es óptico. = He is an optician.

So here, el is not optional, because the sentence is talking about a particular optician.

Here, óptico means optician: a person who works with glasses and vision care.

A few useful notes:

• el óptico = the optician
• óptico can also be an adjective meaning optical
• In some contexts, la óptica can refer to an optician’s shop or to optics as a field

In this sentence, though, El óptico clearly refers to the person.

The written accent in óptico shows where the stress falls: ÓP-ti-co.

Without the accent, Spanish stress rules would make you stress a different syllable, so the accent is necessary.

Pronunciation note for Spain:

• óptico ≈ OP-tee-ko

The accent mark does not change the vowel quality very much; its main job is to mark the stressed syllable.

Revisó is the preterite form, used for a completed action in the past:

• El óptico revisó las gafas. = The optician checked the glasses.

Compare:

• revisa = checks / is checking (present)
• revisaba = was checking / used to check (imperfect)
• revisó = checked (preterite, completed event)

So revisó tells you that the action happened and is viewed as finished.

Revisó is:

• third person singular
• preterite
• from the verb revisar = to check / to inspect / to examine

Full mini-conjugation in the preterite:

• yo revisé
• tú revisaste
• él/ella/usted revisó
• nosotros revisamos
• vosotros revisasteis
• ellos/ellas/ustedes revisaron

So revisó matches El óptico because that subject is he / she / it grammatically, here he.

The accent mark in revisó distinguishes it from reviso.

Compare:

• reviso = I check
• revisó = he/she checked

So the accent matters both for pronunciation and for meaning.

Pronunciation:

• reviso = reh-BEE-so
• revisó = reh-bee-SO

That final accent tells you the stress goes on the last syllable.

Because gafas is normally used in the plural in Spanish, just like glasses in English.

So:

• las gafas = the glasses
• even when you mean one pair

This is very common:

• Necesito mis gafas. = I need my glasses.
• ¿Dónde están las gafas? = Where are the glasses?

In Spain, gafas is the normal everyday word for glasses.

Because gafas is a plural feminine noun, so it takes las.

You can see that from the singular form:

• la gafa = one lens / one eyepiece / sometimes one side of glasses in some contexts
• las gafas = glasses

In practice, learners should mainly remember las gafas as a set phrase for glasses.

Because the personal a is generally used before people or personified beings, not ordinary objects.

So:

• El óptico revisó las gafas. = no a, because gafas are things

But:

• El óptico vio a María. = a is required, because María is a person

This is a very common question for English speakers, since English does not have this feature.

Yes, Spanish word order is more flexible than English, although El óptico revisó las gafas is the most neutral and straightforward order.

For example:

• El óptico revisó las gafas. = neutral statement
• Las gafas las revisó el óptico. = puts emphasis on the glasses
• Revisó las gafas el óptico. = possible, but more marked or stylistically specific

English usually relies more heavily on fixed word order, while Spanish can move things around to change emphasis.

Revisar is a very natural verb here. It usually means to check, inspect, look over, or examine.

In this sentence, it suggests that the optician looked over the glasses to see whether they were correct, damaged, adjusted properly, and so on.

Related verbs:

• mirar = to look at
• examinar = to examine, often a bit more formal
• comprobar = to verify/check

So revisó sounds normal and idiomatic for this kind of practical inspection.

Gafas is the standard everyday word for glasses in Spain.

In other Spanish-speaking countries, you may also hear:

• anteojos
• lentes
• sometimes other regional terms

So if you are learning Spanish from Spain, gafas is exactly the word you want to know.

A Spain Spanish pronunciation would be approximately:

el OP-tee-ko reh-bee-SO las GA-fas

A few details:

• óptico: stress on the first syllable
• revisó: stress on the last syllable
• gafas: stress on the first syllable
• In much of Spain, c before e/i and z are pronounced with a th sound, but that does not affect any word in this sentence

So this sentence is fairly straightforward to pronounce once you notice the written accents in óptico and revisó.