La retina está en el ojo.

In Spanish, it is very common to use the definite article (el, la, los, las) where English might use the, a, or sometimes no article at all.

So La retina está en el ojo sounds natural in Spanish:

• la retina = the retina
• el ojo = the eye

Spanish often uses articles when talking about body parts in a general or anatomical way.

Spanish has two verbs for to be: ser and estar.

Here, estar is used because the sentence talks about location:

• La retina está en el ojo = The retina is in the eye.

A very common rule for learners is:

• ser = identity, origin, characteristics
• estar = location, states, conditions

So:

• La retina es importante = The retina is important.
• La retina está en el ojo = The retina is in the eye.

The accent mark shows where the stress goes when you pronounce the word.

• está is stressed on the last syllable: es-TÁ

It also helps distinguish forms in writing. In this case, está is the he/she/it is or you are form of estar.

Nouns in Spanish have grammatical gender.

• retina is feminine, so it takes la
• ojo is masculine, so it takes el

There is not always a logical reason from meaning alone; gender is part of the word and usually has to be learned with it.

A useful habit is to learn nouns together with their article:

• la retina
• el ojo

In Spain Spanish, ojo is pronounced roughly like OH-ho, but the j is not an English h exactly. It is a stronger, raspier sound made in the back of the throat.

So:

• o = like oh
• j = the Spanish j sound, similar to the ch in Scottish loch for many learners
• final o = oh

Approximation: OH-kho or OH-ho, depending on how precise you want to be.

It is pronounced roughly reh-TEE-na.

A few useful points:

• r at the beginning of retina is a soft tapped r, not a strong English r
• ti here sounds like tee
• stress is on the middle syllable: re-TI-na

Yes, you could. It means something like The retina is inside the eye.

But there is a slight difference:

• en el ojo = in the eye
• dentro del ojo = inside the eye

En el ojo is simpler and very natural. Dentro del ojo is a bit more explicit about being physically inside.

Also note:

• del = de + el

So:

• dentro del ojo = inside the eye

No, that would sound incorrect in standard Spanish.

You need the article:

• en el ojo

Spanish usually requires the article in this kind of phrase.

So:

• correct: La retina está en el ojo
• incorrect: La retina está en ojo

Yes, you could say En el ojo está la retina, and it is grammatically correct.

However, the most neutral and natural order is:

• La retina está en el ojo

Putting En el ojo first can add emphasis or sound more literary or contrastive, depending on context.

For a basic factual sentence, learners should normally stick with:

• La retina está en el ojo

Está is the third person singular form of estar in the present tense.

It can mean:

• he is
• she is
• it is
• also formal you are

Here it means it is, because la retina is a singular thing.

Present tense of estar:

• yo estoy
• tú estás
• él/ella/usted está
• nosotros estamos
• vosotros estáis
• ellos/ellas/ustedes están

Spanish often prefers a simpler structure with articles when talking about body parts or anatomy.

So instead of something like:

• the eye’s retina

Spanish naturally says:

• La retina está en el ojo

This is just the normal way to describe anatomical location. Spanish does not always express possession the same way English does.

Yes.

Singular:

• La retina está en el ojo = The retina is in the eye.

Plural:

• Las retinas están en los ojos = The retinas are in the eyes.

Notice the changes:

• la → las
• retina → retinas
• está → están
• el → los
• ojo → ojos