Was Da Vinci Thinking of the Spherical Lens of the Fish Eye in his Painting Salvator Mundi?

The image of Christ’s robe, seen through the orb held by Christ in the painting Salvator Mundi by the Italian Renaissance artist Leonardo da Vinci, has led to speculation that the orb consists of a glass (or rock crystal, calcite) sphere that is either hollow or solid. Da Vinci’s drawings and notes indicate that he had an intense interest in the optics of the eye and in the natural world around him. Is it possible that he was depicting the optical quality of the spherical fish lens, a lens with a gradient refractive index that neutralizes the spherical aberration that would otherwise exist?