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37 Cards in this Set
- Front
- Back
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What wavelengths of light can the eye process
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400-700 nm
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What are the three layers of the eye (outer to inner) and what does each contain?
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1. Corneosclereal
Cornea - central Sclera - dense CT laterally 2. Choroid or uvea - vasculature 3. Retina - rods and cones |
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What are the functions of the cornea?
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1. Protection
2. Structural support 3. Filtration of undesirable wavelengths 4. Focus image on retina |
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What are the 5 layers of the Cornea and what does each layer contain?
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1. Stratified squamous epithelium
2. Bowman's - random collagen fibrils 3. Stroma - layers of kertocytes and collagen fibrils 4. Descemet's membrane - thick basal lamina, dense collagen 5. Simple squamous epithelium - tight junctions |
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What is myopia?
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Nearsightedness, caused by cornea too far from retina
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What is hyperopia?
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Farsightedness, cornea too close to retina
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What is astigmatism?
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Aspherical cornea --> light not properly focused on retina
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What is Radial Keratotomy?
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Incision near center of cornea to correct mild myopia
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What is astigmatic keratotmy?
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Incision in steepest part of cornea to correct astigmatism
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What is photrefractive keratotomy?
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Laser removes part of corneal epithelium to correct mild/moderate myopia, hyperopia and astigmatism
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What is LASIK?
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Laser removes part of stroma to correct hyperopia, astigmatism, and myopia
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What is the Limbus and what does it do?
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Junction of cornea and Sclera, where Bowman's membrane disappears, vasculature appears
WBC's migrate from here to cornea in inflammation response |
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What is the conjunctiva?
What are the characteristics of its epithelium? |
Lines inner surface of eyelids and eye surface beyond cornea
Continuous with skin epithelium, has goblet cells |
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What is the function of the lens?
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Focus nearby objects on the retina
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What are the 4 structural parts of the lens?
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1. Capsule - collagen and proteoglycans
2. Cuboidal cells - anterior 3. Flattened cell fibers - extend width of lens, gap junctions 4. Zonules - elastic microfibril, fibrillin support lens |
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What is Presbyopia?
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Loss of lens elasticity
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What is cataracts?
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Loss of lens transparency
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What are the functions of the retina?
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1. Photoreception
2. Transmission of images to optic lobe of brain 3. Prevents light backscatter |
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What are the 9 layers of the retina (post to ant)
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1. Rods and codes
2. Outer limiting - tight junctions btwn photoreceptor and Muller glial cells 3. Exteran nuclear layer - cell bodies and nulei of rods and cones 4. External plexiform - photoreceptor axon/interneuron process 5. Internal nuclear - Interneuron cell body 6. Internal plexiform - dendrites of ganglion cells/process of interneurons 7. Ganglion layer - ganglion cell bodies 8. Nerve fiber layer - axons of ganglion 9. Pigmented epithelium - prevent backscatter |
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What can rods do and not do?
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CAN - vision in low light
CANNOT - colors |
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How does rod concentration change from Fovea?
What is the light sensitive pigment and how does it work? |
Increasing concentration as distance increases
Light-sensitive pigment = Rhodopsin --> GPCR bound to vit. A prosthetic group |
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What do cones do, where are the most abundant, and what is the light-sensitive pigment?
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Sense color
Highest conc. in fovea, decrease outward Iodopsin pigment |
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What is the fovea centralis?
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Visual axis with greatest visual acuity
Highest density of photoreceptors, no vessels |
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What is the Macula lutea?
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Yellow pigment around fovea
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Wht is the optic disc?
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Where optic nerve joins retina
Since no rods and cones --> blind spot |
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What are the structures in the choroid/uvea? (5)
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Iris
Ciliary body/processes Vessels Pigmented region Outflow tract |
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What is the job of the iris?
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Regulate amount of light that reaches retina
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What muscles control pupil size and how are they arranged?
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Dilator pupillae = radially from pupil
Constrictor pupillae = circumferentially around pupil |
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What are the posterior and anterior layers of the iris?
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Posterior = layer of blue pigmented cells that blocks light
Anterior = myoepithelial cells with melanin |
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What is the structure of the ciliary body?
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Disk-shaped, hollow core, with lumen of ciliary processes, smooth muscle
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What does the outer layer of the ciliary body contain?
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Pigmented epithelial cells, continuous with pigmented epithelium of iris
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What does the inner layer of the ciliary body contain?
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Non-pigmented, produces zonules that anchor basal lamina to lens capsule
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What are the functions of the ciliary body?
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Accomodate lens, control thickness via zonules
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What happens when the ciliary muscle contracts?
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Zonule tension decreases, lens thickens, increases index of refraction --> near focus
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What do ciliary processes produce?
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Aqueous humor into posterior chamber, moves to anterior chamber passively b/c of pressure difference
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How does aqueous humor move through the eye?
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Ciliary process --> posterior chamber --> anterior chamber --> trabecular meshwork --> canal of Schlemm --> episcleral veins -->general circulation
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What is Glaucoma?
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Buildup of fluid pressure in eye:
Inflow > Outflow |
