4- Visual System Flashcards
What is the function of the retinal pigment epithelium?
Absorb light to prevent excess light rays in the eyeball, causing glare
What are the two type of photoreceptors in the retina?
Cone and rod cells
Which photoreceptor allows for colour and high acuity vision?
Cone cells
Which process do horizontal cells carry out to increase definition of structures in vision?
Lateral inhibition
What is the clinical sign known as amaurosis fugax?
Patients describe it as a curtain coming down over their vision, resulting in sudden vision loss. Sign of central retinal artery occlusion, risk of stroke
What is optical coherence tomography?
A specialist technique used to visualise the layers of the retina
Light from the temporal field is detected by which retinal fibres?
Nasal retinal fibres
Which part of the thalamus do ganglion cell axons of the optic tract project to?
Lateral geniculate nucleus
What is a scotoma?
A small patch of visual loss due to a localised lesion in the retina
Damage to the left optic nerve will give rise to what visual field loss?
Left monocular blindness
Damage to the medial optic chiasm will give rise to what visual field loss?
Bitemporal hemianopia
Damage to the left optic tract or left lateral geniculate causes what type of visual loss?
Right homonymous hemianopia
Damage to the superior optic radiation will give rise to what visual field loss?
Contralateral homonymous inferior quadrantanopia
What is the afferent arm of the pupillary reflex?
Optic nerves
Where do the optic nerves synapse in the pupillary reflex?
Pretectal nucleus
What is the efferent arm in the pupillary reflex?
Oculomotor nerve
What does it mean consensual pupillary constriction?
When light is shone into one eye, the other’s pupil will also contract
What is the afferent arm of the accommodation reflex?
Optic nerve
Which processing centres are involved in the accommodation reflex?
Visual cortex, oculomotor nuclei and Edinger Westphal nuclei
What is the result of the accommodation reflex?
Helps focus on a near object by pupillary constriction, lens thickening and convergence of the eyes
