Optikeren måler hornhinnen under linsetilpasningen.

Because -en is the usual definite ending for many singular common-gender nouns in Norwegian Bokmål.

• optiker = optician / an optician
• optikeren = the optician

So Norwegian usually adds the definite article to the end of the noun instead of putting a separate word like the in front.

Måler is the present tense of the verb å måle, meaning to measure.

• å måle = to measure
• måler = measures / is measuring

In Norwegian, the present tense often covers both simple present and present continuous in English. So måler can mean both:

• measures
• is measuring

depending on context.

Because Norwegian usually does not use a special progressive form like English is measuring.

English:

• The optician is measuring the cornea

Norwegian:

• Optikeren måler hornhinnen

The simple present måler is enough. Norwegian can express an ongoing action without adding an extra verb like is.

Because it is a noun with a definite ending attached:

• hornhinne = cornea
• hornhinnen = the cornea

So it is not two separate words. Norwegian normally writes the noun and its definite ending together.

Also, hornhinne itself is a compound noun:

• horn = horn
• hinne = membrane

So literally it is something like horn membrane, but the actual meaning is cornea.

In Bokmål, many feminine nouns can take either:

• -a definite ending
• or -en definite ending

So for some feminine nouns, both forms may be possible depending on style and dialect.

For hornhinne, you may encounter:

• hornhinna
• hornhinnen

Both can occur, but hornhinnen is a very common Bokmål form, especially in more neutral or formal written language.

Here under means during, not beneath.

So:

• under linsetilpasningen = during the lens fitting

Norwegian under can mean either:

• under / below
• or during

The context tells you which meaning is intended. In this sentence, it clearly means during.

Because linsetilpasningen is the definite form:

• linsetilpasning = lens fitting / a lens fitting
• linsetilpasningen = the lens fitting

In Norwegian, abstract events or procedures are often put in the definite form where English might use either the or sometimes no article at all.

So under linsetilpasningen is very natural for during the lens fitting.

Yes. Norwegian very often combines related nouns into one word.

Here the parts are:

• linse = lens
• tilpasning = fitting / adjustment / adaptation

So:

• linsetilpasning = lens fitting
• linsetilpasningen = the lens fitting

This is completely normal in Norwegian. Where English often uses several words, Norwegian frequently uses one compound noun.

On its own, linse can mean lens in a general sense. But in medical or optician contexts, it often refers to a contact lens.

So linsetilpasning usually means a contact lens fitting unless the context suggests something else.

Because this is a normal main clause with standard word order:

• Optikeren = subject
• måler = verb
• hornhinnen = object
• under linsetilpasningen = adverbial phrase

So the pattern is basically:

Subject + Verb + Object + Adverbial

That is often the same as in English. Norwegian word order becomes more noticeably different in other structures, especially when another element comes first, because then the verb usually moves to second position.

Yes. You could say:

Under linsetilpasningen måler optikeren hornhinnen.

That means the same thing, but now the sentence begins with the time phrase. In Norwegian main clauses, the finite verb usually stays in second position, so when Under linsetilpasningen moves to the front, måler must come before optikeren.

That is a very important Norwegian word-order rule.

Yes, this is standard Bokmål.

A Nynorsk version would likely look different, for example with forms such as:

• optikaren
• måler
• possibly other changes depending on wording

So if you are learning Bokmål, the sentence as written is perfectly normal.

Here are the main noun forms:

• en optiker = an optician

• optikeren = the optician

• ei/en hornhinne = a cornea

• hornhinnen or hornhinna = the cornea

• en linsetilpasning = a lens fitting
• linsetilpasningen = the lens fitting

This is a good reminder that Norwegian nouns often show definiteness by adding the article to the end.

Måler is roughly pronounced like MOH-ler, but the Norwegian å does not sound exactly like any single English vowel.

A few helpful points:

• å is a rounded back vowel, somewhat like the vowel in British law for many speakers
• må- is longer than English mo
• the r in Norwegian varies by dialect

You do not need a perfect accent at first; the key thing is to recognize that å is its own vowel letter in Norwegian, not a plus a symbol.

Not in this sentence unless you also change the meaning.

• Optikeren måler hornhinnen = The optician measures/is measuring the cornea
• En optiker måler hornhinnen = An optician measures/is measuring the cornea

Using bare optiker without en or -en would usually be ungrammatical here. Norwegian nouns normally need some marking for indefiniteness or definiteness in this kind of sentence.