Lecture 31: Eye

• 1. Corneoscleral
• Cornea most refractile part of eye, most imp in focuses image on retina
• 2. Choroid (uvea)
• most of eye's vasculature
• 3. Retina
• photosensitive (rods & cones), neurons, considered part of brain & CNS

• no blood vessels or pigments
• Inflammation from limbus: juction of cornea and sclera, appearance of stroma vasculature & disapperance of Bowman's membrane
• goblet cells in the conjuctiva: statified sq changes to stratified cuboidal
• Stratified squamous epithelium
• Bowman's membrane-collagen fibrils formed by stroma below
• Stroma- thickest, keroatocytes- modified fibroblasts (NOT keratin!), orthagonally arrayed= transparent. continuous in sclera but not the structured arrangement
• Descemet's membrane- basal lamina, diffusion barrier between stroma and anterior chamber
• Corneal endothelium- tight junctions

• problems with cornea
• Myopia- nearsightedness; cornea too far from retina
• Hyperopia- farsightedness; cornea too close to retna
• Astigmatism- light rays can't sharply focus b/c cornea is aspherical

• on Cornea
• Radioal Keratotomy & Astigmatic keratotomy- incisions
• Photorefractive keratotomy (PRK) eximer laser removes corneal epithelium
• Laser assister in-situ keratomileusis (LASIK)- eximer laser removes stroma

• Capsule
• Cuboidal- only epith on anterior side!!
• post-mitotic, anuclear flattens lens fibers runs entire width connected by gap junctions
• zonules- elasic microfibril called fibrillin

• Presbyopia- loss of lens elasticty, NOT corrected by corneal surgery
• Cataracts- loss of lens transparency

• 1. RPE layer- non-neuronal, prevent backscatter
• 2. PR layer- dendrites of PRs (rods & cons)
• 3. Outer limiting membrane- tight junctions between PR neurons and Muller glial cells
• 4. ONL- cell bodies of PRs
• 5. OPL- axons of PRs and axons/dendrites of bipolar, horizontal, amacrine cells
• 6. INL- cell bodies of B,H,A cells
• 7. IPL- dendrites of ganglion cells and axons/dendrites of B,H,A cells
• 8. GCL- cell bodies and axons of ganglion cell neurons, exit eyr thru optic nerve, signals to optic lobe
• 9. NFL- axons of ganglion cells, innermost layer

• Fovea centralis-highest density of PRs, no rods, lots of cons
• Macula lutea- yllo zone around fovea
• Optic disc- where optic nerve joins retina, no retina here =
• "blind spot"

• no anterior layer of epithelium
• posterior chamber-> between iris and lens

• makes aqueous humorpumped into post chamber by inner non-pigmented layer
• outer layer- pigmented, continuous with pigmented iris epith layer
• inner layer- non-pigmented, produce zonules (onto lens), pumps aqueous humor into post chamber

ciliary m contract, loosens zonules, thicken/curve lens-> increase index of refraction can see nearby objects