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43 Cards in this Set
- Front
- Back
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Where is a lesion, that affects vision unilaterally?
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anterior to chiasm
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where is a lesion, that affects vision bilaterally?
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post-chiasm
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Define optic atrophy
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-degeneration of nerve fibers
-wasting away, diminution in size of cell, tissue, organ or part -decrease or total loss of function |
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Where is BDGF produced?
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Ganglion cell layer
Inner nuclear layer |
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Why is BDNF important to the ONH?
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-Differentiation
-survival -function |
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Temporal pallor of the ONH, indicates what type of optic atrophy?
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primary optic atrophy
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true or false
Swelling is seen in primary optic atrophy. |
False
-No swelling prior to atrophy |
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What are the general causes of primary optic atrophy?
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trauma
hereditary |
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What is the pathogenesis of secondary optic atrophy?
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nerve becomes swollen--> nerve fibers are damaged --> swelling recedes --> reduced function results
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Papilledema in both eyes is usually due to?
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systemic problem
-disequilibrium in normal pressure balance |
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True/false
Atrophy of nerve fibers is seen immediately after trauma |
atrophy only more detectible after ~2 months
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true/false
primary optic atrophy can be gradual, progressive through ones life |
true
-if hereditary |
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what type of cells replaces damaged/dead ganglion cells?
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astrocytes
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excess neuroglia in the eye can indicate?
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CNS damage.
-if retinal ganglion cells are damaged, astrocytes proliferate and refill the space |
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What can be visibly seen when there is an increase in astrocytes due to retinal damage?
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Pallor
-caused by reflection of the gliosis caused by astrocytes |
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what is expected with neurotrophic factor deprivation?
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sick RGC
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Secondary optic atrophy in one eye can be due to
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tumor
ophthalmic reasons (vein occlusion, ONH ischemia) |
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What effect is seen on axonal conduction if there is a loss of myelin?
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-changes resistance and capacitance
-may result in complete loss of conduction |
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Myelin causes a decrease in capacitance, how is this good for the axonal conduction?
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less energy is required to maintain ionic gradients
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what is pallor?
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ON is same size
-no loss of tissue -color change -qualitative |
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what is excavation?
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-loss of ganglion cells
-less rim tissue -quantity |
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true/false
Retinal ganglion cell death is reversible |
false
-irreversible |
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true or false
Myelination increases sensitivity to reduced oxygen. |
True
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what is the most common outcome of inflammation in the eye?
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demyelination
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what is the most common cause of of neuropathy in young and middle aged people?
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optic neuritis
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What are some causes that can lead to compression of nerves?
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-tumors
-aneurysms -enlarged EOMs -edema -damage can be reversible |
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What is the most common optic neuropathy?
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glaucoma
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True/false
the optic nerve can repair itself |
false
-there are inhibitory molecules on CNS myelin |
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Why is it important to catch optic neuropathy early?
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vision loss from neuropathy is permanent
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Elevation of intracranial pressure causes optic disc edema, this is called?
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papilledema
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If pituitary adenomas are removed quickly, can visual function return?
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yes
-as long as it hadn't been there too long |
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white or grey matter is less sensitive to hypoxia.
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white matter is less sensitive
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what is Uhthoff's phenomenon?
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-transient worsening of MS symptoms
-loss of conduction due to increased temp |
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what is the pathway of axonal conduction?
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1.adjacent membrane depolarizes
2. voltage sensitive sodium channels open 3. sodium ions move in 4. axon becomes more positive (depolarized) |
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is the inside of the axon negative or positive in relation to the environment?
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negative
-resting potential is negative |
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in axonal conduction in the eye, what is the role of sodium? potassium?
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Sodium- conduction is blocked when sodium is eliminated
Potassium- voltage gated channels |
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An increase in CD ratio of 0.3 represents what percentage lost of RNFL?
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30%
increase 0.1=10% loss of RNFL |
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Excavation causes______.
a. visual field loss b. loss of visual function |
a visual field loss
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Occlusion of what BV causes ischemia of ONH?
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SPCA
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What effect does an increase in pressure cause in a glaucoma patient?
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-interrupts transport
-RGC dont receive neurotrophins |
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What are causes of optic nerve injury due to compression?
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tumors
aneurysms enlarged EOMs edema |
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How does myelin aid in axonal conduction?
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-increases resistance - charge doesn't leak
-decreases capacitance- less energy is required to maintain ionic gradients |
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Sodium flows _____of the axon.
Potassium flows ___ of the axon. |
sodium-into axon
potassium- out of axon |
