Vision is generated by light that hits the retina of the eye. They are far too small to be visible to the naked eye. Angels are not visible to the physical eye. He located many other stars too distant to be visible with the naked eye. Many lichens have apothecia that are visible to the naked eye. Severe pain is present in the eye. CB1 is also found in the human anterior eye and retina. He had to have eight stitches over his left eye. The hospital catered for the treatment of heart, lung and eye problems. The grandfather returned from the war maimed with the loss of his right eye. It is listed for its use in treating eye disease. Codelli based his ingenious design on his understanding of the human eye. He also uses his microscope in checking clues unseen by the naked eye. Loss of function of any of the eye muscles results in ophthalmoparesis. This is associated with increased pressure in the eye.