The writer now focuses on God's relationship with all people. The point is if we can't be grateful for specific things in our own lives, we can always be grateful for the good things that happen in the world around us. This is the main theme found in verses 7-9.
In verse 7 we read, Which executeth judgment for the oppressed. God "upholds the cause of the oppressed". He is a perfect and holy God who knows who is oppressed and suffering. He may physically rescue them in their lifetime or He may choose to rescue them through salvation. God never promises to end all suffering. He does promise we can have joy through the worst of times if we trust in Him for the ultimate outcome of our lives.
Verse 7 goes on to say He (God) gives food to the hungry. The point is God puts a need in people to care for others and their well being. God also made it possible to grow food and raise animals for consumption. Food is a basic as well as a consistent human need that God graciously provides in our life.
The phrase, The LORD looseth the prisoners, probably refers to a practice of cultic law for Israel's most vulnerable citizens that was established in Israel's history (see Exodus 22:21-22, Deuteronomy 24:12). The writer is saying that God even defends their cause.
 The LORD openeth the eyes of the blind: the LORD raiseth them that are bowed down: the LORD loveth the righteous:
The Psalmist declares that God gives sight to the blind. Ultimately one day in the future, God will give sight to every believer who is physically blind. However, the bigger picture is that those who don't care about God at some point in their life can one day "get it". Once they learn to trust in God, the eyes of their "heart" are opened to His existence and His guidance in their lives.
Notice in verse 8, the term "bowed down". This is describing those who humble themselves before God. The "righteous" is about those people who trust in Him and not their own ability to do the right thing. In both cases, it is about humbling ourselves before God in our lives.