Gileadi renders these two verses:
21 They roam about embittered by hunger; and when they are hungry, they become enraged and, gazing upward, curse their king and their God.
22 They will look to the land, but there shall be a depressing scene of anguish and gloom; and thus are they banished into outer darkness.
For verse 22, the NIV has:
22 then they will look toward the earth and see only distress and darkness and fearful gloom, and they will be thrust into utter darkness.
The idea of the darkness at the end of verse 22 is clear, but the special meaning of "outer darkness" for most Latter-Day Saints suggests that "utter darkness" would be the better translation, as these are not a people that would fit the LDS category of those thrust into "outer darkness."
When the Assyrian invasion comes, it will be hard on the people of Judah. Isaiah speaks here of hunger, a theme of the previous prophecy. There will be such hunger and trouble that the people will curse their King (with some justification) and their God (with no justification).
Verse 22 lets us know that when the people look upward, they do it not in hope but in anger. It is their cursings that are directed upward, not their repentance. While looking upward could be a sign of repentance, the following verse makes it clear that these are yet unrepentant, as they also look to the world, and see only darkness and despair.