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80 Cards in this Set

  • Front
  • Back
anatomy of the eye
Emmetropia (normal)
Describe the vision acuity of this individual
Myopia (nearsighted)
Describe the vision of this individual
Hyperopia (Farsightedness)
Describe the vision of this individual
Describe the pathway light takes as it moves through the layers of the eye
Nerve fiber layer
Ganglion cell layer
Inner Plexiform Layer
Inner Nuclear Layer
Outer Plexiform Layer
Outer Nuclear Layer
Pigment Epithelium
Label the different components of the diagram
Label the portions of the visual pathway
Which reflex is this?
Label the parts
The Pupillary Reflex
Which reflex follows a
similar pathway to the
pupillary reflex?
The accomodation /
convergence reflex
Describe the shape
of an accommodated
The lens increases in diameter and approaches a round shape.
Fill in the blanks
Describe Macular Sparing and the theories behind it.
Macular Sparing is due to a cortical lesion
Two theories:
1. Macula occupies a large amount of primary visual cortex: therefore in a cortical lesion it is likely that part will be spared.
1. Watershed region: dual blood supply allows sparing
What are the 3 main layers of the eye?
1. Sclera/Cornea
2. Uveal Tract (Choroid, ciliary body and iris)
3. Retina
What are the 3 chambers of the eye? Which chamber is the largest?
1. Anterior aqueous humor
2. Posterior aqueous humor
3. Vitreous humor
The vitreous humor is the largest
Which layer of the eye is avascular?
The cornea
The sclera and the cornea are for the most part continuous. Where does each begin and end?
The sclera surrounds the posterior 5/6ths of the eyeball. The cornea, then, surrounds 1/6th of the eyeball.
Define the following components of the sclera:
1. Suprachoroidal Lamina
2. Tenon's space
1. melanocytes in loose CT
2. detached region of the sclera at the sclera-cornea junction
From outer to inner:
1. Epithelium - stratified squamous
2. Bowman's membrane
3. Stroma
4. Descemet's membrane
5. Endothelium - simple squamous
What are the 5 layers of the cornea?
The uveal tract is divided into 3 regions. What are they?
1. Choroid
2. Ciliary Body
3. Iris
What is the choroid made of and what is found in this material?
A loose CT matrix that contains fibroblasts, melanocytes, lymphoid cells
What is the layer of the choroid that nourishes the retina called?
Choriocapillary layer
What is the name of the membrane that acts as a barrier between the choroid and the retina?
Bruch's membrane
The ciliary body is actually a ________ that has extensions called _________.
Ciliary muscle, ciliary processes
What is the function of the ciliary processes?
Anchors lens and aids in lens accommodation
Accommodation is _________ focusing while the iris controls _______ focusing.
fine, coarse
What is the function of ciliary epithelium?
secrete aqueous humor of anterior and posterior chamber
The sympathetic nervous system innervates which pupillary muscle?
dilator pupillae
The parasympathetic nervous system innervates which pupillary muscle?
sphincter pupillae
Label the layers of the lens
Give a characteristic of each
1. Lens Capsule - thick basal lamina
2. Subcapsular epithelium - "stem cell" (regenerating) cell layer of the lens
3. Lens fibers - filled with crystallin protien that refracts light
What are the 3 layers of the retina?
What is found in each layer?
From outer to inner:
1. outer layer - photoreceptor cells
2. middle layer - bipolar neurons
3. inner layer - ganglion neurons from optic nerve
What is this a slide of?
Name the layers
Where are Muller cells found?
What is their function?
The retina - they are specialized astrocytes that form the internal and external limiting membranes
Name the non-nuclear layers of the Retina.
How many rods are in the average retina and where are they located within the retina?
~120 million
more concentrated along the edges of the retina
Which are extremely light sensitive: rods or cones?
Rods - they see black & white and are used in night vision
What is rhodopsin and where is it found?
photopigment; found in disks of rod cells
How many cones are in the average retina and where are they located within the retina?
~6 million (less than rods)
more concentrated along back of retina and fovea
Which are extremely color sensitive: rods or cones?
What is an amacrine cell and where is it found?
Various neurons in the retina: they synapse with different photoreceptors. function not understood
What is a Limbus and where is it found?
trabecular meshwork at corneoscleral junction; contains canal of Schlemm
How does aqueous humor drain from the anterior chamber into the episcleral vasculature?
Via the canal of Schlemm
What are the components of the vitreous humor?
H2O - 99%, collagen, hyaluronic acid molecules
There are no ___________ at the blind spot. What is another name for the blind spot?
Optic papilla or optic disc is another name
What are the glands of Moll and Zeis and where are they found?
both found in eyelid
Moll - sweat gland
Zeis - sebaceous gland
Which cells make synaptic contact in the outer plexiform layer of the retina?
photoreceptors, bipolar and horizontal cells
Which cells make synaptic contact in the inner plexiform layer of the retina?
bipolar, amacrine, ganglion cells
[cGMP] is ________ (high/low) in the photoreceptor cell in the dark.
high (photoreceptors are activated at in the dark: cGMP keeps the ion channels open)
Light closes cation channels to inactivate the photoreceptors. They are closed in a 3 step process - what is it?
1. Light activates pigment molecules in disc membrane
2. activated pigment stimulates a G-protein. THis G-protein activates cGMP phosphodiesterase (which breaks down cGMP)
3. as cellular [cGMP] is lowered the channels close. This reduces the inward cation current and the cell hyperpolarizes.
light coming from the right visual field is projected onto the ________ portion of the left retina and the _______ portion of the right retina.
The fovea is always ________ to the optic disc
Where does the fovea sit in the visual field?
Where does the blind spot sit in the visual field?
In the center
slightly lateral to the fovea
The Lateral Geniculate Nucleus (LGN) is found _______.
in the posterior portion of the thalamus
Where does the 1st synapse in the visual pathway occur?
At the LGN
Optic fibers associated with the fovea project onto the ________.
posterior calcarine cortex
Meyers loop contains ________ visual fields which project ____________.
on the inferior calcarine fissure.
The _______________ portions of the visual field stay ipsilateral, whereas the ___________ portions of the visual field cross at the _________.
Optic Chiasm
Pupillary light reflex:

1. receptors?
2. afferent limb?
3. CNS center?
4. efferent limb?
5. peripheral effector?
1. photoreceptors
2. CN II
3. pretectal area (tectal=midbrain)& Edinger-Westphal nuclei.
5. sphincter pupillae (bilaterally)
Is there a decussation in the pupillary light reflex? If so, where is it?
Yes. In the CNS (pretectal area and E-W nuclei)
Information decussates here b/c there is bilateral projection from the pretectal area to the E-W nuclei via the posterior commissure)
The Accommodation reflex:
1. Receptors?
2. Afferent Limb?
3. CNS centers?
4. Efferent Limb?
5. Peripheral Effector?
1. photoreceptors
2. CN II
3. Lateral Geniculate Body, primary visual cortex, E-W nuclei
5. sphincter pupillae muscle (pupillary constriction) and ciliary body muscle (lens accommodation)
When the ciliary body muscles are contracted what happens to the lens? Why?
The lens gets fatter. Tightening the ciliary body muscle releases tension on the suspensory ligaments of the lens: this allows the lens to fatten
To see far away how is your lens shaped?
To see close up how is your lens shaped?
far away --> stretched out and thin
close up --> fat
What is an Argyll-Robertson pupil? What is it a sign of?
pupils are:
don't react to light
DO constrict on accommodation
A sign of neurosyphilis
What is Horner's syndrome?
any damage to sympathetic pathways in either the brainstem, intermediolateral cell column or superior cervical ganglion.
How does a lesion in descending sympathetics present?
1. ptosis (drooping eyelid)
2. miosis (constricted, fixed pupil)
3. anhydrosis (no sweating on ipsilateral face)
The sympathetic pathway has 3 synapses. Where are they?
1. brainstem (hypothalamus)
2. intermediolateral cell column in an upper thoracic spinal cord segment
3. superior cervical ganglion
The smooth muscle elevator of the eyelid is ___________ active.
What is the major function of the superior colliculus?
Integration of visual, auditory and somatosensory information resulting in orientation to a particular stimulus. Can be via head, eye or neck movements.
Where does the tectospinal pathway originate?
the superior colliculus; it is a descending motor pathway
If a visual field defect was only in one eye, where would the lesion be?
In the optic nerve of the affected eye (before the optic chiasm)
an area within the visual field where vision is absent or depressed. (artificial BLIND SPOT)
complete loss of vision in one or both eyes
loss of vision in one half of the visual field of one or both eyes
homonymous hemianopia
hemianopia restricted to one visual field (L or R)
heteronymous hemianopia
loss of vision in opposite halves of the visual field. (ie. bilateral temporal field is lost)
loss of vision in a quadrant of a visual field
Meyer's loop carries information from which visual field?
Where does it project?
Superior visual field
Projects to the inferior calcarine cortex
Fibers from the inferior visual fields project where?
Superior calcarine cortex
Function of Tectospinal Pathway?
Controls neurons that innervate proximal and axial musculature (common function - orient head to sensory stimulus)
Blood supply to primary visual cortex?
Blood supply to macula's area on the primary visual cortex?
PCA (Posterior Cerebral Artery)
Macula has both MCA and PCA
What is iodopsin and where is it found?
iodopsin is the photopigment used by cone photoreceptors.
3 different varieties