Visual system Flashcards
What is the outer layer in the eye called?
sclera - continuous dural sheath of optic nerve
what is the Uvea made up of and what is a property of this layer?
outer choroid, inner ciliary body and iris
pigmented and vascular layer
what are the layers of the retina from superficial to deep?
Retinal pigment epithelium photoreceptor cells bipolar cells ganglion cell layer nerve fibre layer
why is retinal epithelium pigmented ?
to prevent light bouncing so to stop glare
What are bipolar cells in the nervous system and how do they achieve lateral inhibition ?
first order neurones
connected via horizontal cells to enhance edges
What receives input from bipolar cells?
ganglion cells
where does the macula sit from the optic disc?
lateral
what is amaurosis fugax ?
sudden visual loss due to occlusion of central retinal artery
What is used to view the layers of the retina?
OCT- Optical coherence tomography
what is the medial retina referred to ?
nasal retina
what is the lateral retina referred to ?
temporal
What does the optic tract project ?
ganglion cells axons to the lateral genticulate nucleus in the thalamus
what do the optic radiations project?
lateral genticulate to visual cortex
what is a scatoma?
localised defect in to retina causing a small patch of visual loss
how do you name which side the lesion is on?
the side with the lateral visual loss
how do you get macula degeneration ?
non-vascular damage to occipital lobe
how can you get macular sparing visual loss?
occlusion of the posterior cerebral artery.
Where do the superior radiations project to ?
the parietal lobe
where do the inferior radiations project to ?
temporal lobe
Why is there a consensual reflex?
the pretectal nucleus projects bilaterally to EDW nuclei
What is the accommodation reflex?
Pupil constriction, convergence of eyes and thickening of lens
What is the processing centre for the accommodation relfex?
Visual cortex via lateral geniculate nucleus to oculomotor and edinger westphal nucleus
