The eye is one of the most complex parts of the human body, provides light to the rest of the body.
(Matthew 6:22) "The eye is the lamp of the body; so then if your eye is clear, your whole body will be full of light. (NAS95)
(Matthew 6:22) The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light. (KJV)
In the previous verses Jesus was speaking about storing up treasures in heaven, in verse 24 He states that no one can serve 2 masters , sandwiched in between are verses 22-23 which speak about the eye and it’s function is to be the light of the body which dispels darkness. The KJV translates the word sound or clear as single, scholars believe that the point is to be focused on a single point similar to (Proverbs 4:25-27) Let your eyes look directly ahead And let your gaze be fixed straight in front of you. Watch the path of your feet And all your ways will be established. Do not turn to the right nor to the left; Turn your foot from evil. (NAS95) OR (Hebrews 12:2) fixing our eyes on Jesus, the author and perfecter of faith, who for the joy set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God. (NAS95)
All of these passages are teaching the same thing: Have a distinct object in view, devoted to one object, steady, unwavering, fixed on the object of our affection—Jesus Christ, His son and our Savior.
Other scriptures describe different type of eyes:
Bright eyes—Prov. 6:17 Failed eyes--- Psa. 38:10
Open eyes—Mt. 20:33 Closed eyes—Mt. 13:15
Blessed eyes—Mt. 13:16 Lustful eyes—1 John 2:16
Seeing eyes—1John 1:1 Blinded eyes—1 John 2:11
Enlightened eyes—Psa 19:8 Haughty eyes—Prov 6:17
Fixed eyes—Heb. 12:2 Foolish eyes—Prov. 17:24
Returning to the text [Mt. 6:22-23] if the whole body is full of light then our conduct will be steady because the eyes will be fixed on Jesus. Looking to Jesus the author and finisher of our faith, who is the perfect example of how to run the race that is set before us. [ Heb 12:1] We are in the race of life, how successful we are will depend on how well we follow His example, in endurance, determination, and strength, which allows us to finish the course, giving Him the glory.
The Proverb writer used the term “wise in your own eyes” as a warning we should be ”looking to Jesus” NOT to ourselves, so we can finish the course, keep the faith and receive the crown of righteousness awarded to ALL who faithfully finish the course.