What does Psalm 6:7 mean?

Whether from an illness, fearful stress, or simply from tears, David's grief caused his eyesight to fail. Here, he lays the blame for his poor eyesight on his foes. Unfortunately, in a lapse of faith he had taken his eyes off the Lord and placed them on his enemies. It is debilitating to stop looking to the Lord for protection and guidance.

When a fierce storm arose on the Sea of Galilee, Jesus walked on the water toward the disciples, whose boat was being buffeted by the waves and wind. The disciples saw Jesus, but they thought they were seeing a ghost. However, the Lord assured them that it was He and told them not be afraid. Peter answered, "Lord, if it is you, command me to come to you on the water" (Matthew 14:28). At Jesus' command, Peter began walking on the sea toward Jesus. But, when he took his eyes off Jesus and saw the wind, Peter began to sink. Jesus saved Peter, though, by taking hold of him and escorting him back to the boat.

Whatever the cause, David must have felt that he was sinking. His eyes were dull, and he needed to focus on the Lord.