S. R. Faruqi:

The opening-verse is by way of introduction, but it's not devoid of pleasure. The first point is that in both lines there's the care taken with the 'setting' [tar.sii((]-- that where a metrical foot ends, there a word ends. In Ghalib and Iqbal, this quality is frequently found.

A second point is that to call the eyes an evident 'proof' is fine, because the eyes (and especially red eyes) are after all the most conspicuous part of the face-- or rather, of the body.

A third point is that the way blood-closed eyes are a proof that there's no blood in the liver, in the same way the presence of the liver is a proof that the eyes will be blood-closed, because the blood of the liver is drawn along and always comes into the eyes. Between 'eyes' and 'evident' there's also the relationship of a zila.

Qa'im has versified the theme of blood congealing in the eyes much better than Mir has:

vuh ma;hv huu;N kih mi;saal-e ;habaab-e aa))iinah
jigar se ashk nikal tham rahaa hai aa;Nkho;N me;N

[I am so absorbed that, like a bubble in a mirror
having emerged from the liver, tears are halting in the eyes]

FWP:

SETS
MOTIFS == LIVER; MIRROR
NAMES
TERMS == METER; PROOF

Why does the liver, the blood-making organ (in the ghazal world), 'long for' more blood? Because the speaker has been using up his blood so quickly: he has had it flowing out from a wound in his heart, and also from his eyes as he sheds tears of blood. The proof of the liver's need for more blood is that now the speaker's tears of blood have 'congealed' in his eyes-- a sign that the flow of fresh blood has slowed or stopped.

It's also an enjoyable touch that the proof of this situation is 'evident, conspicuous', so that anybody can see it-- except the speaker himself, whose eyes have been sealed shut by the clotted blood.

Qa'im's verse assumes a glass mirror; older hand-blown glassmaking methods tended to produce wavy or bubbly effects.