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What is the pathway of the opthalmic system
- Retina
- Optic Nerve
- Optic Chiasm
- Optic tract
- Lateral Geniculate body
- Suprachiasmatic nucleus
- Pretectal nuclei
- Superior colliculus
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What is the role of the Pretectum in the opthalmic system
Reflex control of pupil and lens
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What is the role of the superior colliculus in the opthalmic system
Orienting the movements of the head and eyes
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In the mammalian retina besides the conventional rod-cone system, what also exists
Malanopsin-associated intrinsic (RGC) photoreceptive system which conveys info for Circadian rhythm
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Stereo vision
The eyes see two different pictures, the brain puts them together to give depth perception
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What do the right and left cortex see
Right cortex sees the the left visual feild, and the left the right
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What are the clinical signs of the pituitary tumour pressing on the optic chiasm
- Bitemporal hemianopia (loss of the temporal visual fields)
- Bitemporal hemianopia is often caused by
- Chiasma lesion or pituitary adenoma
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Where do the retinal ganglion cells end
Lateral geniculate nucleus
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Where is the primary visual cortex
Around the calcarian fissure in the occipital lobe
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What is the difference in what the primary and secondary visual cortex sees and what the associated visual cortex sees (use an apple as an example)
- 1o & 2o see a green round object
- Associated cortex fills in the rest
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In respect to the associated visual cortex (extrastriate areas) a parietal lesion would present itself how
There would be a deficit in the "where" pathway (spatial orientation, size, motion)
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In respect to the associated visual cortex (extrastriate areas) a temporal lobe lesion would present itself how
Deficit in the "what pathway" (recognition of color, naming, and face recognition)
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In respect to the associated visual cortex, what is the difference in awareness of patients with a Temporal lobe lesion and a Parietal lobe
lesion
- Patients with a temporal lobe lesion are aware that there is a problem and will compensate for it
- Patients with a Parietal lobe lesion are unaware of their deficit
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What portion of the brain is used for facial recognition
Medial temporo occipital lobe (Fusiform gyrus)
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Retrochiasmal lesions have what clinical signs
Contralateral Homonymous visual deficits (ex. Right field in both eyes)
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Loss of blood supply to what arteries would cause a retrochiasmal lesion
- Posterior cerebral artery
- Middle cerebral artery
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Quadrantanopia
A loss of sight affecting a quarter or quadrant of the field of vision
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Periventricular leukomalacia (PVL)
- White matter lesion around ventricles
- Peripheral lower visual field deficits
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Temporal epilepsy
- Very common, can be resistant to antiepileptic medication
- Performing a lobectomy can fix it
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What is the complication with a lobectomy at the anterior temporal lobe
Contralateral superior quandrantanopia
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Anton Syndrome
When a patient has blindness but fervently believes that they can see. The patient can describe objects they haven't previously seen but in complete error and they are oblivious to it
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Occipto-temporal cortical disorder
- Trouble recognizing objects and naming them
- But can recognize them buy hearing or touching them
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Visual agnosia
The inability of the brain to recognize familiar objects or faces
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What is the effect of a Occipito-parietal lesions
Trouble seeing things in motion
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Autoprosopagnosia
Person doesn't recognize themselves in the mirror
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Prosopagnosia
- Disorders of face recognition
- Typically results from bilateral lesions of the lingual and fusiform gyri
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Flashing and lightning seen in the eye can be caused by
Retinal detachment (no pain)
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Small flashing in the eye accompanied by pain can be caused by
Optic neuritis
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