The Eye
[ image 1 ] [ image 2 ] [ image 3 ] [ image 4 ] [ image 5 ] [ Eye Review ]
As before, try to identify the structures on the image before reading the text.
On this image, we can identify the cornea (A), the sclera (B), the junction between these two = the limbus (C), and the optic nerve (D). Notice how the optic nerve originates ventral to the posterior pole of the globe. The cornea and sclera comprise the outer fibrous tunic of the eye. The cornea is normally transparent due to its nonkeritinized surface maintained the tear film, its dehydration state, its regularly arranged fibers, the absence of pigment and blood vessels, and the lack of myelination on the nerves fibers.
After removing a portion of the cornea, we can now identify the pupil (E), which is a hole through which light and aqueous humor pass. Aqueous humor is produced by the ciliary bodies; it passes from the posterior to the anterior chamber; and it drains through the spaces of Fontana at the iridocorneal angle (F). The muscles of the iris (G) regulate the size of the pupil. The cloudy layer on the interior surface (image on the right) is the pars optica retinae. Dorsal to the optic disc (H) is the tapedum lucidum (I) of the otherwise darkly pigmented choroid (J). What is the purpose of the tapedum lucidum?
This is an internal view of the anterior half of the globe. The cloudy pars optica retinae ends at a scalloped (serrated) junction called the ora serrata (K). Anterior to this junction are ridges from which you will find fibers extending to suspend the lens. These ridges are the ciliary bodies (L), and the ciliary zonules or zonular fibers suspend the lens (M).
The cloudy appearance of the cornea, lens and optic portion of the retina is artifact from fixation and cooling.
Click on [Eye Review] to review the structures of the eye.