בדיקת הראייה מודדת חדות ראייה.

Because בדיקת is the construct form of בדיקה (test / examination).

In Hebrew, when one noun is followed by another noun to mean X of Y, the first noun often changes into a construct form:

• בדיקה = a test / an examination
• בדיקת = test of ...

So:

• בדיקת הראייה = the eye test / literally the test of the vision

This is a very common Hebrew pattern:

• בית ספר = school, literally house of book
• חדר מיון = emergency room, literally room of sorting/triage
• בדיקת דם = blood test

The ה is the definite article, meaning the.

So:

• ראייה = vision / eyesight
• הראייה = the vision / the eyesight

In a construct chain like בדיקת הראייה, the definiteness is usually shown on the second noun, not the first.

So:

• בדיקת ראייה = an eye test / a vision test
• בדיקת הראייה = the eye test

Even though בדיקת itself does not get ה, the whole phrase becomes definite because the second word is definite.

Because the subject, בדיקת הראייה, is feminine singular.

The base noun is בדיקה, which is feminine, and its construct form בדיקת is still feminine. Hebrew verbs in the present tense agree with the subject in gender and number.

So:

• מודד = masculine singular
• מודדת = feminine singular
• מודדים = masculine plural / mixed plural
• מודדות = feminine plural

Since בדיקת הראייה is feminine singular, the correct form is:

• בדיקת הראייה מודדת

Because את is normally used before a definite direct object, and חדות ראייה here is indefinite.

Compare:

• הבדיקה מודדת חדות ראייה = The test measures visual acuity
  → no את, because the object is not definite

But if you said:

• הבדיקה מודדת את חדות הראייה = The test measures the visual acuity / the sharpness of the vision

then את would appear, because the object is definite.

So the absence of את tells you that חדות ראייה is being treated as a general concept: visual acuity.

Because the two phrases mean different things grammatically:

1. בדיקת הראייה = the eye test
   Here הראייה is definite, so the whole construct phrase is definite.

2. חדות ראייה = visual acuity / sharpness of vision
   Here the phrase is indefinite and functions more like a general term.

So even though the same noun appears twice, its role is different in each phrase.

A useful way to see it:

• הראייה = the eyesight / the vision
• ראייה = eyesight / vision

And:

• חדות ראייה is almost like a set expression meaning visual acuity

חדות comes from the adjective/root idea of sharpness.

So:

• חד = sharp
• חדות = sharpness

In חדות ראייה, it literally means sharpness of vision, which is the standard Hebrew way to say visual acuity.

This is another construct phrase:

• חדות = sharpness
• חדות ראייה = sharpness of vision

So the sentence is structurally:

• בדיקת הראייה = the vision test
• מודדת = measures
• חדות ראייה = visual acuity

ראייה is pronounced roughly like re-i-YA.

The א here is not usually a strong consonant in everyday speech, but historically it marks a separation between vowels. For learners, it helps to think of the word as having three parts:

• ר
• א
• ייה

So instead of one smooth syllable, it is more like:

• re-i-yah

This is why the word may look a little unusual in writing.

In everyday Israeli pronunciation, many speakers do not strongly pronounce the א, but it still affects the structure of the word.

Yes, literally that is how the structure works, but in natural English you would usually say:

• the eye test
• the vision test
• the eyesight test

So grammatically, Hebrew is using an of relationship:

• בדיקת הראייה = test of the vision

But natural translation usually sounds less literal.

This is very common when learning Hebrew: understand the literal structure, but translate it idiomatically.

Yes. This is a very normal Hebrew word order:

subject + verb + object

• בדיקת הראייה = subject
• מודדת = verb
• חדות ראייה = object

So the sentence pattern is straightforward:

• The eye test measures visual acuity

Hebrew can sometimes move things around for emphasis, but this version is the neutral, standard order.

Yes, but it would mean something slightly different.

For example:

• הבדיקה מודדת חדות ראייה = The test measures visual acuity

This is more general and uses a simple noun with the definite article.

But:

• בדיקת הראייה מודדת חדות ראייה = The eye test measures visual acuity

This is more specific, because it names the particular kind of test.

So both are grammatical, but בדיקת הראייה is more precise.

Yes, it is very useful to learn it as a set phrase.

• חדות ראייה = visual acuity
• literally: sharpness of vision

Even though you can analyze it grammatically, it is common enough that it is worth remembering as one unit, especially in medical or optometry contexts.

Similarly useful phrases are:

• בדיקת ראייה = eye test
• לקות ראייה = visual impairment
• שדה ראייה = field of vision

So yes: treat חדות ראייה as both a grammatical construct phrase and a vocabulary item.