Die oogtoets gaan die sigsveld en die oogdruk na.

Because this is the separable verb nagaan, which means to check, inspect, go over, or examine.

In a main clause, Afrikaans often splits a separable verb into:

• the conjugated verb part earlier in the sentence: gaan
• the particle at the end: na

So:

• nagaan = to check
• Die oogtoets gaan ... na = The eye test checks ...

Here, gaan is not being used with its basic meaning to go. The meaning comes from the whole verb nagaan.

That is normal for separable verbs in Afrikaans main clauses.

With nagaan, the na part moves to the end:

• Die oogtoets gaan die oogdruk na.

But when the verb stays in its full form, it is written together:

• Die oogtoets wil die oogdruk nagaan.
• Ek dink dat die oogtoets die oogdruk nagaan.

So the split form is not random; it follows a regular grammar pattern.

Yes in form, but not in meaning by itself.

Afrikaans uses the same form gaan, but in this sentence it is part of nagaan. So you should understand it as part of one verb, not as the ordinary movement verb to go.

A good English comparison is something like:

• go vs. go over
• take vs. take off

The little extra part can change the meaning a lot.

Afrikaans main clauses usually follow the verb-second rule.

That means the finite verb normally comes second in the clause:

• Die oogtoets
  • gaan
    • die sigsveld en die oogdruk
      • na

So even if the sentence begins with something else, the verb still stays second:

• Vandag gaan die oogtoets die sigsveld en die oogdruk na.

This is very typical Afrikaans and similar to Dutch and German word order.

Because one definite article can cover both nouns when they are joined by en and both are being understood as definite.

So:

• die sigsveld en die oogdruk

means:

• the visual field and the eye pressure

Afrikaans does not need to repeat die before the second noun, although it can sometimes be repeated for emphasis or clarity:

• die sigsveld en die oogdruk
• die sigsveld en die oogdruk

In this sentence, using it once is the most natural choice.

No. That is one of the nice things about Afrikaans.

die is used for:

• singular definite nouns
• plural definite nouns
• all grammatical genders

So Afrikaans does not do things like:

• the / der / die / das
• masculine vs. feminine vs. neuter article changes

You just use die for the.

Examples:

• die oog = the eye
• die oë = the eyes
• die toets = the test
• die toetse = the tests

Because Afrikaans normally writes compound nouns as one word.

These are compounds:

• oogtoets = oog

  • toets
    eye + test

• sigsveld = sigs

  • veld
    sight/vision + field

• oogdruk = oog

  • druk
    eye + pressure

English often uses separate words where Afrikaans prefers one compound word. This is very common, so learners should get used to looking for one long noun instead of several smaller ones.

That -s- is a linking sound used in some compounds.

So sigsveld is built from:

• sig = sight, vision
• linking -s-
• veld = field

It does not add a separate meaning like a plural or possessive here. It just helps form the compound in the standard way.

These linking sounds are common in Afrikaans compounds, but they are not always fully predictable, so it is best to learn the whole word as a unit:

• sigsveld, not sig veld

You would usually say:

Die oogtoets gaan nie die sigsveld en die oogdruk na nie.

Afrikaans typically uses double negation:

• one nie after the verb area or before the object area, depending on structure
• another nie at the end of the clause

Because this sentence has a separable verb, the final nie comes after the final particle na.

In compounds, the main stress is usually on the first part.

So approximately:

• OOG-toets
• SIGS-veld
• OOG-druk

A few pronunciation notes:

• oog has a long vowel, roughly like the vowel in Scottish-style go, but not exactly English.
• g in Afrikaans is usually a throaty sound, not the English g in go.
• ui is not in this sentence, so the pronunciation is a bit easier than in many Afrikaans words.

Even if your pronunciation is not perfect yet, getting the stress on the first part of each compound will already make you sound more natural.