Mam dalekowzroczność.

Because Polish normally expresses a condition or ailment with mieć (to have) + a noun.

So:

• Mam dalekowzroczność. = I have farsightedness.

If you want to use jestem (I am), you need an adjective, not this noun:

• Jestem dalekowzroczny. — male speaker
• Jestem dalekowzroczna. — female speaker

So Jestem dalekowzroczność would be incorrect.

Usually, no. Polish often drops subject pronouns because the verb already shows the person.

• Mam clearly means I have

So the normal neutral sentence is simply:

• Mam dalekowzroczność.

You would add ja only for emphasis or contrast, for example:

• Ja mam dalekowzroczność, a on krótkowzroczność.

It is in the accusative, because mieć takes a direct object.

However, this noun looks exactly the same in the nominative and accusative singular:

• nominative: dalekowzroczność
• accusative: dalekowzroczność

That is normal for many feminine nouns ending in -ość.

Because this type of noun often has the same form in nominative and accusative singular.

English speakers often expect a visible change in case, but in Polish that does not always happen. Here, the grammar changes, but the spelling stays the same.

So even though the word is functioning as the object of mam, its form remains dalekowzroczność.

Because Polish has no articles.

English says:

• I have farsightedness
• I have a condition
• the condition

Polish usually expresses those ideas without a/an/the. Context tells you whether something is definite or indefinite.

So Mam dalekowzroczność is complete and natural without any article.

A rough English-friendly approximation is:

dah-leh-koh-VZROCH-noshch

A few useful parts:

• w sounds like English v
• cz sounds like ch in chop
• ść at the end is a soft sound, roughly like shch
• the stress falls on the second-to-last syllable: dalekowzroczność

So the stress is on wzrocz.

It is correct and understandable, but it can sound a bit clinical or matter-of-fact, because it names the condition directly.

In everyday speech, some people might also say:

• Jestem dalekowzroczny / dalekowzroczna.

That said, Mam dalekowzroczność is absolutely fine, especially in a medical or explanatory context.

Both refer to farsightedness / hyperopia.

Very roughly:

• nadwzroczność is often the more technical or medical term
• dalekowzroczność is a common understandable term and is also used outside strict medical language

In many situations, people will understand either one. If you are speaking with an eye doctor or reading medical material, you may often see nadwzroczność.

Yes. That is a correct alternative.

Use:

• Jestem dalekowzroczny. — if the speaker is male
• Jestem dalekowzroczna. — if the speaker is female

The difference is mainly grammatical:

• Mam dalekowzroczność. uses a noun: I have farsightedness
• Jestem dalekowzroczny/dalekowzroczna. uses an adjective: I am farsighted

Both are possible.

The neutral, most natural order is:

• Mam dalekowzroczność.

Polish word order is fairly flexible, but changing it usually adds emphasis, contrast, or a special tone. For example:

• Dalekowzroczność mam, nie krótkowzroczność.

That sounds contrastive or marked, not like the default way to say it. So for normal use, stick with Mam dalekowzroczność.

Yes. Besides the literal medical meaning, it can also be used figuratively to mean foresight or long-sightedness in planning or thinking.

For example, in a non-medical context it could describe someone’s ability to think ahead.

But in a sentence like Mam dalekowzroczność, especially if you are talking about vision or glasses, people will usually understand the medical meaning.