Ophthalmos (ὀφθαλμός) is the common Greek word for eye, appearing about 101 times in the NT. It refers to the physical eye as the organ of sight but is used extensively in metaphorical and theological contexts relating to spiritual perception, moral condition, and desire.
The eye in ancient anthropology was not merely a sensory organ but the window of the soul — the organ through which inner character is revealed and through which external influences enter the heart.
Jesus' teaching on the eye is one of his most penetrating psychological and spiritual insights. "The eye is the lamp of the body. So, if your eye is healthy, your whole body will be full of light, but if your eye is bad, your whole body will be full of darkness" (Matt. 6:22-23). The "healthy eye" (haplous, literally "simple/generous") is focused, undivided in its gaze toward God; the "bad eye" is covetous, divided in its loyalties.
The eye also features in Jesus' exhortations about lust (Matt. 5:29 — better to gouge out an eye than to sin) and the warning about judging others while blind to your own fault (Matt. 7:3-5, the plank and the speck). Spiritually, the Pharisees were blind — they could see physically but not perceive the Kingdom (John 9:39-41). The man born blind who was healed stands as a parable of the whole gospel: Christ opens the eyes of those who cannot see, while those confident in their own vision remain in darkness.