The light of the body is the eye: if therefore thine eye be singlethy whole body shall be full of light. But if thine eye be evil, thy whole body shall be full of darkness (Matthew 6:22-23KJV).
If you have double vision, you see two things where you should see only one. Double vision occurs when your eyes are misaligned. In the same way, if you do not align your spiritual eyes to Christ, you will complicate your life and lose the joy of simplicity. Jesus taught us that our eyes indicate whether we are full of light or full of darkness. Two people can look at the same situation and see two very different things. One person may only see a problem, but the other may see an opportunity to change direction.
Jesus’ understanding of the eye of light far exceeds the concept of physical sight. The Hebrew mindset of "seeing" refers to one's viewpoint on life and attitude toward people. The key to enjoying life with its many ups and downs is to love and to receive love. God is light, and He is love. He is on our side making all things work out for our good if we are walking in His purposes and His love.
When we doubt who God is, we cannot trust Him; we live a volatile and problematic life. But if we slow down and devote our inner being to Christ things get clearer for us. We develop a simple desire to serve God by caring for others. Self-gain and frustration, like a gnat, we easily shoo away for the selfless life which brings us great gain.
God created us to see with a single eye of light. We have no desire be double-minded, two-faced, double-talkers who live a double life because of a double heart. We are one in Him!