S. R. Faruqi:

From the second line it's clear that the eyes are not useless. But nevertheless, nothing is coming into view. The reason for this can be that the world has become black in his eyes; or that he considers everything in the world to be unreal/insubstantial; or again that he is so absorbed in his imagining of the beloved, or in his own grief, or in his own existence itself, that he doesn't even see anything else.

An interesting aspect of the first line is that the very 'proof' of the world's existence in our eyes is that it has no existence. Between jahaa;N meaning 'world' in the first line, and jahaa;N as a relative pronoun in the second line, there is an 'iham of sound' [iihaam-e .saut].

FWP:

SETS == MUSHAIRAH; REPETITION
MOTIFS == EYES; GAZE
NAMES
TERMS == IHAM; PARADOX

The first line grabs our attention by deliberately playing with a logical paradox. For what else could it be to say that in the speaker's view the existence of the world 'is' the nonexistence of the world? (Can 'A' be flatly equated with 'not-A'?) Then the second line slips out through the back door by saying, in effect, 'I can't see anything of the world'. So we realize that what the speaker really meant in the first line was that the existence of the world was to his eyes (and not just 'in his view/opinion') indistinguishable from the nonexistence of the world, since he was unable to see it. That claim, however odd and perplexing (since he doesn't seem to be blind), is not inherently paradoxical.

This is what I call a 'mushairah' or '1,2' verse, since the order of the two lines is crucial to its effect. If we read the two lines in reverse order, the verse entirely loses its punchiness, since the first line then does not create the effect of paradox.

The possible secondary reading of jahaa;N as 'world' in the second line comes so close to working! If the gaze might go 'as far as the world', then nothing is visible. Such a reading would open the possibility that the gaze might not go that far-- because the speaker is so thoroughly detached or removed from the world, or because his gaze might be so limited or otherwise occupied. But then we would need if not an agar or jab , at least a to to establish the clause structure; and we don't have it. Still, I can feel this reading hovering (mainly, perhaps, because I enjoy the doubleness).

Note for grammar fans: Here is another case in which the apnii is used freely rather than with strict grammatical correctness; it can be considered to be short for merii apnii (or else hamaarii apnii , since the subject can only be inferred).