To better understand cytomegalovirus retinitis, it helps to understand the anatomy of the eye.

Structures of the eye include:

• Bony orbit and extraocular muscles:
• The bone around the eye that protects it and the muscles that move the eyeball in the socket
• Conjunctiva:
• The thin, clear membrane that covers the white part of the eye, as well as the inside surface of the eyelids
• Sclera:
• The strong, white, outer layer of the globe
• Cornea:
• The clear, firm cap that protects the pupil and the iris
• Pupil:
• The opening that allows light to pass to the lens
• Iris:
• The colored part of the eye that controls the size of the pupil
• Lens of the eye:
• The clear, soft disc that receives light through the pupil and focuses images on the retina
• Ciliary body:
• Contains muscles that control the shape of the lens.
• Vitreous:
• The clear gel inside the globe that helps to maintain the shape of the eye
• Choroid:
• The thin layer that contains blood vessels that supply the parts of the eye
• Retina:
• The retina is to the eye what film is to a camera. It is a thin membrane in the back of the eye that contains the rod and cone cells for vision. After receiving light, the retina sends messages to the brain though the optic nerve. This information is processed into images by the brain.