Synsfeltet er større med enkeltstyrkeglassene.

Because Danish usually puts the definite article at the end of the noun.

• et synsfelt = a visual field / a field of vision
• synsfeltet = the visual field / the field of vision

So -et is the neuter singular definite ending, equivalent to English the.

Større is the comparative form of stor.

• stor = big / large
• større = bigger / larger
• størst = biggest / largest

So er større means is larger. Danish, like English, uses the comparative when comparing something, even if the thing being compared to is only understood from context.

Because Danish can leave the second half of the comparison unstated when it is obvious from context.

So Synsfeltet er større ... means The field of vision is larger ..., and the listener is expected to know larger than what from the surrounding text or situation.

If you wanted to state it explicitly, Danish could use end for than:

• Synsfeltet er større end med flerstyrkeglas.

Med usually means with, and here it means something like when using or with the help of.

So:

• med enkeltstyrkeglassene = with the single-vision lenses
• more naturally in English: when wearing/using the single-vision lenses

This is a very common use of med in Danish.

Danish often forms compound nouns by joining words together.

This word can be understood as:

• enkelt- = single
• styrke = strength / prescription
• glassene = the lenses

So the whole compound means the single-vision lenses or the single-prescription lenses.

Writing it as one word is normal in Danish. English often writes similar ideas as two or more words, but Danish prefers compounds.

For the same reason as synsfeltet: Danish often adds the to the end of the noun.

So:

• glas = lens/lenses or glass
• glassene = the lenses / the glasses

In this sentence, it refers to optical lenses, not drinking glasses.

It is plural definite: the single-vision lenses.

The ending -ene is a common plural definite ending in Danish nouns.

So the sentence is talking about a set of lenses, not just one lens.

Because comparative adjectives in Danish are usually the same regardless of gender or number.

So større stays større whether the noun is:

• common gender
• neuter
• singular
• plural

That makes it simpler than basic adjective forms like stor/stort/store.

Yes. It is a very standard sentence pattern:

• Synsfeltet = subject
• er = verb
• større = complement
• med enkeltstyrkeglassene = prepositional phrase

So the structure is basically:

[Subject] + [verb] + [description] + [extra information]

That is completely normal in Danish main clauses.

Usually no, not in the same way.

• med focuses on the means or situation: with / when using
• for often means for in the sense of benefit, purpose, or recipient

Here the idea is that the field of vision is larger when using those lenses, so med is the natural choice.