today we're going to do an ayah dissection start by examining the external features of the eye if there are any muscles left behind take a note of their features and locations the straight muscles are rectus muscles this is the superior rectus the lateral rectus and the medial rectus on this I dissection there's also a superior oblique muscle left but the inferior rectus and inferior oblique have been cut if you have eye muscles left cut through them to make room for your dissection there may also be conjunctival membrane left over the eye if there's any conjunctiva remaining also cut through the conjunctiva this outer portion of the eye is the fibrous layer the white is the sclera the clear portion is the cornea the cornea allows light through the eye you're going to start by cutting through the sclera try to make a hole in the side of the sclera it's very tough and it may take a couple of cuts to get through be careful of your fingers here and that the eyeball doesn't slip out of your fingers once you get a cut you can make a circular cut all the way around just outside of the cornea continue with that circular cut until it is complete then you can open the eyeball like a book and lift the cornea on the underside of the cornea the iris and a portion of ciliary body will remain attached if you do this carefully the lens and vitreous humor will stay behind there's the lens and vitreous humor place the back of the eye down for a moment and will view the cornea and the structures behind it use a blunt probe to remove the iris from the back of the sclera and cornea pull the iris off and take a look at its features we can now see that this is a brown colored eye the iris contains muscles that constrict and dilate the hole in the center which is the pupil there's also a portion of ciliary body left on this specimen the ciliary body now can be viewed from behind let's take a look at the lens in this dissection the entire eyeball has been fixed with solution so the lens is very tough in an eye that is fresh the lens will be very delicate and see-through we can now remove the vitreous humor this jelly-like substance in the back of the eye pullout the vitreous humor and what's remaining is the neural layer this is the retina the retina contains the photoreceptors which are sensitive to light it's a very thin layer on the back of the eye the central collection of photoreceptors is the macula lutea with the fovea on the back of the eye you will view where the axons exit the optic nerve that then leaves a blind spot in the eye where the blood vessels and axons from those nerves exit through the optic nerve you can now peel back the retina and see the very thin layer and then it remains attached at the optic disk this exit point what's left in many animals is this shiny shell like structure called the tepee dome lucidum this reflects light and is useful for night vision this is not present in humans you can now view all of the structures of the eye the cornea the iris the lens the vitreous humor the retina and the tip edom lucidum let me know if you have any questions