Lecture Wednesday September 19: histology of the eye

Recognize the basic anatomy of the eye



1. Cornea
3 main layers from outside in: corneal epithelium, stroma, corneal endothelium



2. Sclera
Irregular connective tissue

3. Choroid
Vascularized connective tissue
Anteriorly forms:
- Ciliary Body (ciliary process produces aqueous humor, and ciliary muscle that functions to change the shape of the lens).
- Iris contains constrictor papillae muscle (parasympathetic CN III) and dilator pupillae muscle (sympathetic)
- scleral venous sinus (canal of Schlemm) for drainage of aqueous humor produced by the ciliary body



4. Retina and Pigmented Epithelium

Pigment epithelium important for recycling products of the rods and cones

Layers of the retina


1. Outer nuclear layer = Rods and Cones that depolarize in response to light stimulation
2. Outer plexiform layer = processes of rods and cones that synapse on the cells of the inner nuclear layer
3. Inner nuclear layer = several types of neurons that process the information from the rods and cones
4. Inner plexiform layer = processes of neurons from the inner nuclear layer that synapse on the ganglion cells.
5. Ganglion cell layer = neurons whose axons give rise to the optic nerve.
6. Nerve fiber layer = axons of the ganglion cells

Clinical correlations
1. Cataract - clouding of the lens
2. Glaucoma - Increased ocular pressure due to blockage of aqueous humor drainage through the scleral venous sinus (canal of schlemm)
3. Papilledema- bulging of the optic disc due to increased intracranial pressure.


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