Term
| Retina covers entire posterior eye except ___ |
|
Definition
|
|
Term
|
Definition
depression on the retina which is thin and contains only cone receptors. Is in the middle of the macula. Is the location of greatest visual acuity. |
|
|
Term
| where blood vessels travel in the eye |
|
Definition
| through the middle of the optic nerve |
|
|
Term
| Describe the optic cup vs disc |
|
Definition
Cup is outer part aka the optic nerve head
Disc is the central part where the vessels go into (is a hole) |
|
|
Term
| embryologic origin of the eye |
|
Definition
|
|
Term
| # of synapses in the eye/retina and what kind of potential it makes |
|
Definition
Only 2 synapses (photoreceptor to bipolar then bipolar to ganglion)
Makes a graded potential, not an action potential (except for the ganglion cell) |
|
|
Term
| What are the 9 layers of the retina? |
|
Definition
Outtermost to innermost:
Choroid>
Bruchs membrane>
Retinal pigment epithelium (absorbs light)> Outer nuclear layer: contains photoreceptors>
Outer plexiform layer: horizontal cells which regulate on-center and off-center. Determines what gets through to the ganglion cells>
Inner nuclear layer: bipolar cells= take info from horizontal cells and photoreceptors and transmit to ganglion cell>
Inner plexiform layer: contains amacrine cell>
Ganglion cell layer: send info to the lateral geniculate nucleus>
Nerve fiber layer |
|
|
Term
| What are the 2 cells that do interneuron pathways in the retina (lateral inhibitory or excitatory connections)? |
|
Definition
| Horizontal and amacrine cells |
|
|
Term
| What is the distribution of rods and cones in the retina? |
|
Definition
Cones are in the middle of the retina and Rods are out to the side
This way the central vision is most clear
There is a 20:1 ratio of rods:cones in the total eye |
|
|
Term
| Cones have a __:__ synapse with ganglion cells |
|
Definition
|
|
Term
| What are the 2 types of ganglion cells in the retina? How do they differ? Where do they project to? |
|
Definition
A cells (parasol cells)
-Large cell bodies, large receptive fields, mainly concerned with rods (are achromatic, high contrast, movement, peripheral vision)
-Project to the magnocellular layers of the lateral geniculate nucleus (layers 1 and 2)
-Rods use rhodopsin
B cells (Midget cells)
-Are 1:1 for cones
-Small cell bodies, fine vision, detailed, color
-Project to the parvocellular layer of the lateral geniculate (layers 3-6)
-Cones use photopsin |
|
|
Term
| At what point does the optic nerve become myelinated? |
|
Definition
| Posterior to the lamina cribosa |
|
|
Term
| What arteries supply the optic nerve? |
|
Definition
Optic nerve gets blood supply from ICA to ophthalmic artery which supplies:
-Central retinal artery and vein (central)
-Posterior ciliary artery (peripheral) |
|
|
Term
| Why does optic neuritis hurt? |
|
Definition
| There is sensory innervation to the dura surrounding the optic nerve (V1) |
|
|
Term
| What are the steps of the visual pathway (just vision itself)? (6) |
|
Definition
| Retina >optic nerve > temporal visual field fibers decussate at optic chiasm > lateral geniculate nucleus > upper quadrant of visual field through temporal lobe, lower quadrant through parietal lobe > Occipital lobe calcarine cortex (area 17) |
|
|
Term
| What artery supplies the optic chiasm and optic tract? |
|
Definition
|
|
Term
| What artery supplies the lateral geniculate nucleus (LGN)? |
|
Definition
| Anterior and posterior choroidal (PCA) |
|
|
Term
| What artery supplies the upper/parietal optic radiations |
|
Definition
|
|
Term
| What arteries supply the lower/temporal optic radiations? |
|
Definition
|
|
Term
| What is the pathway of the pupillary light reflex/ constriction? (5 steps) |
|
Definition
1. Bypasses lateral geniculate nucleus and goes straight to the pretectal nucleus -> 2. posterior commissure to contralateral pretectal nucleus (inside the superior colliculus) AND ipsilateral Edinger westfall nucleus where it synapses -> 3. projections along CN III to the 4. ciliary ganglion where the pathway synapses for the second time -> 5. pupillary muscles
Uses parasympathetics for constriction
|
|
|
Term
| What is the pathway for pupillary dilation? (5 steps) |
|
Definition
1. Hypothalamus -> lateral medulla down to 2. T1 with 1st synapse in the spinal cord (sweat fibers come off before the superior cervical ganglion) -> 3. loops around and travels up the common carotid -> 4. synapse on the superior cervical ganglion -> 4. travels up the ICA -> 5. levator palpebrae and pupillary muscles |
|
|
Term
| What do pilocarpine drops do? |
|
Definition
| are miotic (constriction via parasympathetics, using acetylcholine) |
|
|
Term
| What do phenylephrine and cocaine drops do? |
|
Definition
| mydriatic (pupillary dilation) via norepinephrine (prevents reuptake) |
|
|
Term
| How does atropine affect pupils? |
|
Definition
mydriatic (pupillary dilation) via anticholinergic |
|
|
Term
| How does the hydroxyamphetamine test work? |
|
Definition
Distinguishes preganglionic lesions (before the superior cervical ganglion, b/c it stimulates NE release). Specific use for Horner’s Syndrome.
-If lesion is preganglionic (in 1st or second order neuron)= both pupils dilate
-If lesions is postganglionic aka in 3rd order neuron= Bad postganglionic pathway does NOT dilate
1st order neuron is hypothalamus to intermediolateral column in thoracic cord (acetylcholine)->2nd order neuron is intermediolateral column to superior cervical ganglionon the carotid (acetylcholine)-> 3rd order is the superior cervical ganglion to the eye (norepinephrine) |
|
|
Term
| What is a medication for Tb that can cause red-green color blindness? |
|
Definition
|
|
Term
| What are the 3 types of cones in the retina? |
|
Definition
Small wavelength: blue and yellow
Medium ": green
Long ": red |
|
|
Term
Leber's Optic Neuropathy
- Pathophys, who, symptoms |
|
Definition
| A mitochondrial disease (point mutation) that destroys retinal ganglion cells due to NADH dehydrogenase deficiency causing central vision loss |
|
|
Term
Foster Kennedy
- Main features (4) |
|
Definition
| Olfactory groove meningioma causing optic nerve atrophy in ipsilateral eye, papilledema in other eye, loss of smell |
|
|
Term
Ischemic optic neuropathy
|
|
Definition
- NAION: sudden painless visual loss upon waking, pale optic disc
- AION: (A is arteritic), basically GCA |
|
|
Term
|
Definition
Dark spot in part of visual field
Central scotome: central lesion
Peripheral scotoma: glaucoma |
|
|
Term
Adie's Pupil
- Symptoms and cause
- Tx |
|
Definition
| Tonically dilated pupil due to parasympathetic disorder. Reacts better to accommodation than light. Constricts (and treat) with pilocarpine |
|
|
Term
Marcus Gunn aka relative APD
- Cause
- Presentation |
|
Definition
Cause: optic nerve/retina damage
Presentation: bad pupil looks like it dilates on swinging flashlight test |
|
|
Term
Argyl Robertson pupil
- Symptoms
- Pathophysiology |
|
Definition
Light near dissociation: pupils constrict much less in response to light than to accomodation.
Lesion to Edinger Westfall efferent fibers (periaqueductal gray)
Usually in tertiary syphilus |
|
|
Term
Retinitis Pigmentosa
- Pathophys
- Genetics
- Tx |
|
Definition
Progressive destruction of rods with progressive night blindness and visual field loss
RPE65 gene which encodes for rhodopsin
Tx: high dose vitamin A |
|
|
Term
| Name the 6 nuclei of CN III and what each supplies |
|
Definition
Medial nucleus: CONTRALATERAL superior rectus
Central caudal nucleus (only one of this): Bilateral levator palpebrae (keeps eyelids the same)
Edinger-Westfall nucleus: Bilateral pupillary constrictors (keeps pupils the same)
Dorsal nucleus: ipsilateral inferior rectus
Intermediate nucleus: ipsilateral inferior oblique
Ventral nucleus: ipsilateral medial rectus |
|
|
Term
What ganglion does the edinger westfall nucleus project to and synapse on?
What nerve does this run with? |
|
Definition
The ciliary ganglion
Runs with the oculomotor nerve on the outside |
|
|
Term
| What runs through the cavernous sinus? |
|
Definition
-ICA is medial, with CN VI just lateral to it
-CN III lies the most superior and lateral with the parasympathetics just lateral to that
-CN IV is just below it
-V1 and V2 are the most inferior on the lateral side |
|
|
Term
| What can a PCA aneurysm cause? |
|
Definition
|
|
Term
| Describe the pathway of the PPRF |
|
Definition
Frontal eye field -> CROSS MIDLINE to PPRF-> CN6 nuclei (and off to ipsilateral CN6)-> CROSS MIDLINE in MLF to CN 3 nuclei
Frontal eye fields look away
PPRF looks towards |
|
|
Term
Perinaud Syndrome
- Cause
- What is seen (4) |
|
Definition
Cause: Dorsal midbrain lesion such as pineal tumor
Features: upward gaze palsy, convergence retraction nystagmus, light near dissociation, bilateral lid retraction |
|
|
Term
Setting Sun Sign
- Cause
- What is seen |
|
Definition
Hydrocephalus in babies/children
Compression of periaqueductal structures |
|
|
Term
1 1/2 syndrome
- Result
- Cause |
|
Definition
Only intact horizontal eye movement is one eye is able to abduct
Lesion to the contralateral MLF and abducens nucleus |
|
|
Term
What cortical layer is the primary visual cortex found in?
What brodmann area is it? |
|
Definition
|
|
