האופטומטריסט בודק את העדשה בלי שהוא נוגע באישון.

The prefix ה־ is the Hebrew definite article, equivalent to the in English.

So:

• אופטומטריסט = optometrist
• האופטומטריסט = the optometrist
• עדשה = lens
• העדשה = the lens

Hebrew attaches the definite article directly to the beginning of the noun instead of writing it as a separate word.

את is the direct object marker. It appears before a definite direct object.

Here, העדשה is definite because it has ה־, so Hebrew uses את:

• בודק את העדשה = checks the lens

This את does not have a meaning you usually translate into English. It is mainly a grammatical marker.

Compare:

• בודק עדשה = checks a lens
• בודק את העדשה = checks the lens

Because the subject is האופטומטריסט, which is grammatically masculine singular here.

In Hebrew present tense, the verb agrees with the subject in gender and number:

• בודק = masculine singular
• בודקת = feminine singular
• בודקים = masculine plural or mixed plural
• בודקות = feminine plural

So if the subject were a female optometrist, you would say:

האופטומטריסטית בודקת את העדשה...

It can mean either one, depending on context.

Hebrew present tense often covers both:

• he checks
• he is checking

So האופטומטריסט בודק את העדשה could mean either:

• The optometrist checks the lens
• The optometrist is checking the lens

Hebrew usually does not force you to distinguish those two the way English often does.

Both are possible, but they are slightly different in style.

• בלי לגעת = without touching
• בלי שהוא נוגע = without him touching

The version with שהוא makes the subject more explicit. It is a fuller clause, not just an infinitive.

So:

• האופטומטריסט בודק את העדשה בלי לגעת באישון
  = a more compact way to say it

• האופטומטריסט בודק את העדשה בלי שהוא נוגע באישון
  = a more explicit way, emphasizing he as the one not touching

In many everyday contexts, native speakers might prefer the shorter בלי לגעת when the subject is already obvious.

שהוא is made of:

• ש־ = that / who / which or a general subordinator
• הוא = he

Together here, it introduces a subordinate clause:

• בלי שהוא נוגע = without him touching

This is one of the common things ש־ does in Hebrew: it connects one clause to another.

You can think of it loosely as:

• בלי = without
• שהוא נוגע = that he is touching / him touching

Even if that sounds awkward in literal English, it is a normal Hebrew structure.

Because the verb לגעת takes the preposition ב־.

So in Hebrew you touch something by saying literally touch in something:

• לגעת באישון = touch the pupil
• לגעת בעין = touch the eye
• לגעת ביד = touch the hand

Because the verb requires ב־, the noun is not a direct object here, so you do not use את.

That is why you get:

• נוגע באישון
  not
• נוגע את האישון

Because it is a combination of:

• ב־ = in / on / at / with, depending on context
• ה־ = the
• אישון = pupil

When ב־ joins ה־, they contract:

• ב + ה + אישון → באישון

So באישון means in the pupil or, with this verb, simply the pupil after touch.

The same thing happens with other prepositions too:

• בבית = in the house
• לילד = to the boy
• מהספר = from the book

נוגע is the masculine singular present-tense form of the verb לגעת = to touch.

So:

• נוגע = touches / is touching for a masculine singular subject
• נוגעת = feminine singular
• נוגעים = masculine plural or mixed plural
• נוגעות = feminine plural

In this sentence, it agrees with הוא inside שהוא נוגע.

Yes. The sentence follows a very normal pattern:

subject + verb + object + additional clause

So:

• האופטומטריסט = subject
• בודק = verb
• את העדשה = direct object
• בלי שהוא נוגע באישון = subordinate phrase

A native speaker would understand this easily.

That said, Hebrew also allows other natural phrasings, for example:

• האופטומטריסט בודק את העדשה בלי לגעת באישון
• בלי לגעת באישון, האופטומטריסט בודק את העדשה

The original order is straightforward and natural.

It is grammatical and understandable, but many native speakers would probably choose the shorter version:

האופטומטריסט בודק את העדשה בלי לגעת באישון

That is because when the subject is the same in both parts of the sentence, Hebrew often prefers the infinitive construction בלי + infinitive.

So:

• בלי שהוא נוגע באישון = fine, more explicit
• בלי לגעת באישון = often more compact and idiomatic

Still, the version you were given is useful because it clearly shows how Hebrew can build a clause after בלי.

Because of the grammar.

• האופטומטריסט is the subject
• בודק agrees with that subject
• את העדשה marks the lens as the direct object

The marker את is especially helpful here. It signals that העדשה is receiving the action.

So the structure is clearly:

The optometrist checks the lens

not the other way around.

In this sentence it is definite, because באישון includes the definite article.

As explained earlier:

• ב + ה + אישון → באישון

So this is specifically the pupil, not just a pupil.

If it were indefinite, you would normally expect באישון without the article only in a different form, but with אישון beginning with א, the spelling can look similar to learners. What matters is the grammar of the contraction: here it is understood as ב + ה.

So in this sentence, it is best read as the pupil.