إجهاد العين وازدواج الرؤية مشكلتان اليوم.

Because this is a nominal sentence in Arabic. In the present tense, Arabic usually does not use a separate word for is/are.

So:

• إجهاد العين وازدواج الرؤية = the subject
• مشكلتان = the predicate
• اليوم = today

The idea is simply: Eye strain and double vision [are] two problems today.

If you wanted a past or future meaning, Arabic would use a verb such as كان.

Because the sentence is talking about two things:

1. إجهاد العين
2. ازدواج الرؤية

Since there are exactly two items, Arabic uses the dual form rather than the plural.

• singular: مشكلة = a problem
• dual: مشكلتان = two problems
• plural: مشكلات = problems

So مشكلتان is the natural choice here.

Because مشكلتان is in the nominative case.

In this sentence, مشكلتان is the predicate (خبر) of a nominal sentence, so it is nominative.

For dual nouns:

• nominative: -ان
• accusative/genitive: -ين

So:

• مشكلتان = nominative
• مشكلتين = accusative or genitive

Here the nominative is correct.

The noun مشكلة is grammatically feminine because it ends in ة (tāʾ marbūṭa).

When a feminine noun is made dual in the nominative, the ending becomes:

• ة → تان

So:

• مشكلة → مشكلتان

This is a very common pattern.

Because إجهاد العين is an iḍāfa construction, often called a genitive or possessive construction.

In an iḍāfa:

• the first noun is the main noun: إجهاد = strain
• the second noun specifies it: العين = the eye

So the second noun is in the genitive case.

That is why it is العينِ if fully vowelled.

The same thing happens in:

• ازدواج الرؤية

where الرؤية is also genitive.

Arabic often uses a singular body-part noun in general expressions where English may use a plural or a fixed expression.

So إجهاد العين is the standard way to say eye strain as a condition or phenomenon.

It does not necessarily mean only one eye is affected. It is a general term, much like a dictionary label.

They are definite because they are part of fixed, specific noun phrases in iḍāfa constructions:

• إجهاد العين = strain of the eye / eye strain
• ازدواج الرؤية = doubling of the vision / double vision

In Arabic, the second noun in an iḍāfa can be definite, and that makes the whole phrase definite or specific in reference.

So these are not random nouns; they are established expressions.

In nominal sentences, the predicate is often indefinite, especially when it tells you what something is.

Here, مشكلتان means two problems as new information about the subject.

So the pattern is very natural:

• definite subject: إجهاد العين وازدواج الرؤية
• indefinite predicate: مشكلتان

If you said المشكلتان, it would sound more like the two problems, which is a different idea.

اليوم is being used as an adverb of time: today.

Arabic often uses time words directly, without a preposition, when they function adverbially.

So:

• اليوم = today
• غدًا = tomorrow
• أمس = yesterday

In a fully vowelled sentence, this would usually be اليومَ, because it functions as a ẓarf zamān (adverbial accusative of time).

Yes, depending on context.

In many sentences, اليوم can mean:

• today in the literal sense
• these days / nowadays in a broader sense

So this sentence could mean either:

• these two issues are problems today
• these two issues are problems in the modern situation / nowadays

Context decides which reading is intended.

A careful fully vowelled reading would be approximately:

إجهادُ العينِ وازدواجُ الرؤيةِ مشكلتانِ اليومَ

Word by word:

• إجهادُ — nominative
• العينِ — genitive, because of iḍāfa
• وازدواجُ — nominative
• الرؤيةِ — genitive, because of iḍāfa
• مشكلتانِ — dual nominative
• اليومَ — adverb of time, accusative

In normal pause, some final short vowels may not be pronounced.

Because ازدواج begins with hamzat al-waṣl (a connecting alif), not a full pronounced hamza in all positions.

When you start from the word itself, you pronounce it with a helping vowel:

• ازدواج → roughly izdiwāj

But when it comes after another word, especially after و, that initial helping vowel often drops in connected pronunciation.

So in flow, وَازدواج is pronounced more like:

• wazdiwāj

This is normal connected Arabic pronunciation.

Grammatically, it is a coordinated subject made of two noun phrases joined by و:

• إجهاد العين
• ازدواج الرؤية

So it behaves like two things together, which is why the predicate is dual:

• مشكلتان

You can think of it as two coordinated subjects functioning together as the topic of the sentence.

Usually, with two coordinated items like this, the most straightforward choice is the dual predicate:

• مشكلتان

A singular predicate would normally change the meaning or sound less natural here. The sentence is clearly classifying the two items as two problems, so the dual is the best match.

So for standard MSA, مشكلتان is exactly what a learner should expect.