arteria ciliaris OS epicanthic fold eyeball human face palpebra canthus arteria lacrimalis nictitating membrane oculus dexter ciliary artery arteria centralis retinae crystalline lens uveoscleral pathway third eyelid sensory receptor lacrimal apparatus OD cornea simple eye stemma iris lacrimal artery sclerotic coat sclera eyelid ciliary body optic lens uvea lid visual system vena lacrimalis choroid eye muscle retina pupillary sphincter face naked eye central artery of the retina musculus sphincter pupillae eye compound eye ocellus choroid coat receptor conjunctiva epicanthus orb ocular muscle lacrimal vein aperture sense organ lens of the eye peeper oculus sinister