Kontaktlinsen ligger på hornhinnen.

Because kontaktlinsen is the definite singular form of kontaktlinse.

• kontaktlinse = a contact lens
• kontaktlinsen = the contact lens

In Norwegian, the definite article is often added as an ending instead of being a separate word. So where English uses the, Norwegian often uses a suffix like -en, -et, or -a.

For the same reason: it is also in the definite singular.

• hornhinne = a cornea
• hornhinnen = the cornea

A useful extra point: hornhinne is a noun that can be treated as feminine in Bokmål, so you may also come across hornhinna as a definite form. Both can be acceptable in Bokmål, depending on style and preference.

Norwegian often uses the definite form when talking about a specific thing in a specific situation.

Here, the sentence is about:

• a particular contact lens
• the cornea it is on

Also, with body parts, Norwegian often uses the definite form where English might still use the or sometimes a possessive depending on context. So hornhinnen sounds very natural here.

Norwegian often prefers a position verb instead of just to be when describing where something is.

So instead of a simple equivalent of is, Norwegian often uses:

• ligger = lies / is lying
• står = stands
• sitter = sits / is attached
• henger = hangs

In this sentence, ligger describes the contact lens as being located on the surface of the cornea. English usually just says is, but Norwegian often wants a more specific verb.

Yes, you may hear sitter in similar contexts, but the nuance is slightly different.

• ligger focuses on the lens as resting/lying on the surface
• sitter can suggest that it is attached, fitted, or staying in place

So ligger is a straightforward location description, while sitter can sound a bit more like the lens is properly positioned and adhering as expected.

På is used because the lens is understood as being on the surface of the cornea.

That matches a very common use of på in Norwegian:

• på bordet = on the table
• på veggen = on the wall
• på hornhinnen = on the cornea

If you used i, that would suggest being inside something rather than on its surface, so på is the natural choice here.

The sentence follows normal main-clause word order:

• Kontaktlinsen = subject
• ligger = verb
• på hornhinnen = prepositional phrase showing location

So it is:

Subject + Verb + Place

This is a very common and neutral Norwegian sentence pattern.

Exactly. Norwegian very often forms compound nouns as one word.

So:

• kontakt
  • linse → kontaktlinse

This is very normal in Norwegian. English sometimes writes similar ideas as one word, two words, or with a hyphen, but Norwegian much more consistently prefers a single compound word.

Yes, in a way. Norwegian often does not need to say whose body part it is if that is obvious from context.

So instead of something like on her cornea or on the cornea of the eye, Norwegian can simply say på hornhinnen if the relevant cornea is already clear.

This is common with body parts in Norwegian.

Ligger is the present tense of ligge.

The present tense is used because the sentence describes a current state or a general fact about where the contact lens is. Norwegian uses the present tense very naturally for this kind of description, just as English does in sentences like The book is on the table.