El óptico revisó la pupila y la retina.

Not exactly.

In Spain, un óptico is usually an optician or someone who works with glasses, lenses, and vision care in an optical shop. An oftalmólogo is an ophthalmologist, a medical eye doctor.

In everyday learner materials, óptico may sometimes get translated loosely as eye specialist, but in real usage there is a difference. So this sentence sounds natural, but depending on the context, a Spaniard might choose oftalmólogo if they specifically mean a doctor.

The accent mark shows where the stress goes:

• óptico → stress on the first syllable: ÓP-ti-co

Without the accent, Spanish spelling rules would make you expect a different stress pattern. The written accent tells you clearly that the stress is on óp-.

The accent mark distinguishes the third-person singular preterite form from the present tense form:

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

So in this sentence:

• El óptico revisó... = The optician checked...

The accent is important because it changes both pronunciation and meaning.

Because revisó is the preterite, which is commonly used for a completed action in the past.

• revisó = checked / examined once, as a finished event
• revisa = checks / is checking
• revisaba = used to check / was checking

So El óptico revisó la pupila y la retina presents the examination as a completed past action.

Spanish often uses the definite article with body parts when it is already clear whose body parts they are.

So instead of saying:

• his/her pupil
• his/her retina

Spanish commonly says:

• la pupila
• la retina

This is very normal with body parts and clothing, especially when the owner is obvious from context.

For example:

• Me duele la cabeza = My head hurts
• Se lavó las manos = He/She washed his/her hands

Because the personal a is mainly used before specific human beings (and sometimes pets or personified beings), not before things or body parts.

Compare:

• Veo al médico = I see the doctor
• Veo la retina = I see the retina

In your sentence, la pupila and la retina are direct objects, but they are not people, so no personal a is used.

No. Pupila can have more than one meaning.

Common meanings include:

• pupil of the eye
• in some contexts, female pupil/student or someone under care or guardianship

In this sentence, because it appears with retina, it clearly means the pupil of the eye.

Spanish usually repeats the article when two nouns are joined and each noun has its own article.

So:

• la pupila y la retina

This is more natural than:

• la pupila y retina

Repeating the article helps make the phrase sound complete and standard.

Normally, y means and.

It changes to e only before words that begin with the i sound, to avoid an awkward repetition of sound.

For example:

• padre e hijo
• España e Italia

But here the next word is retina, which starts with an r sound, so it stays:

• la pupila y la retina

A helpful pronunciation guide is:

el ÓP-ti-ko reh-bi-SÓ la pu-PI-la ee la reh-TI-na

A few notes for Spain:

• óptico: stress on ÓP
• revisó: stress on the last syllable
• v in revisó sounds very close to b
• y before a consonant sounds like ee

Spanish can often omit subject pronouns like él, but it does not usually omit a full noun subject if you want to state who did the action.

So:

• Revisó la pupila y la retina = He/She checked the pupil and the retina
• El óptico revisó la pupila y la retina = The optician checked the pupil and the retina

The second sentence is used when you want to name the person explicitly.

Yes, revisar works well here. It often means:

• to check
• to examine
• to inspect
• to review

In a medical or vision context, revisar can naturally mean to examine.

So revisó la pupila y la retina could also be understood as:

• examined the pupil and the retina

Grammatically, it sounds like the pupil and the retina in a general sense, probably referring to the patient’s eye examination. The sentence itself does not explicitly say whether one eye or both eyes were checked.

If Spanish wanted to be more specific, it could say something like:

• las pupilas y las retinas = the pupils and the retinas
• del ojo derecho = of the right eye

So your sentence is natural, but somewhat general.