Human eye of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock. The eye is not shaped like a perfect sphere, rather it is a fused two-piece unit, composed of the anterior segment and the posterior segment. The anterior segment is made up of the cornea, iris and lens. The cornea is transparent and more curved, and is linked to the larger posterior segment, composed of the vitreous, retina, choroid and the outer white shell called the sclera. The cornea is typically about 11.5 mm (0.3 in) in diameter, and 1/2 mm (500
His Eye Is on the Sparrow His Eye Is on the Sparrow "His Eye Is on the Sparrow" is a Gospel hymn. The song was written in 1905 by lyricist Civilla D. Martin and composer Charles H. Gabriel. It is most associated with actress-singer Ethel Waters who used the title for her autobiography. Mahalia Jackson's recording of the song was honored with the Grammy Hall of Fame Award in 2010. The theme of the song is inspired by the words of David in the Psalms and Jesus in the Gospel of Matthew in the Bible: "I will instruct thee and teach thee in the way which