vision Flashcards
what are the two classes of ganglion cells
magnocellular and parvocellular
what are the eye changes in albinism
nystagmus, astigmatism, hypoplasia of optic nerve
what are the differences between magnocellular and parvocellular pathways
M: motion sensitive pathway and luminance control; L: fine detail and colour vision
what is the split of pathways in reticular radiation
inferior fibres => through Meyers loop of temporal lobe ; superior fibres => through parietal lobe
what are the orientation columns
arrangement of neurons of similar receptive fields in orientation columns=> horizontal, vertical R and L oblique
What is a blob
interaction of orientation column relate to colour vision
what are the hyper-columns
columns that lines between orientations in a region
what is Amblyopia
lazy eye : Abnormalities within the eyes that lead to the brain ignoring one of the eyes to prevent double vision
what is starbism
misalignment of the eyes
what is anisometropia
refractive differences between two eyes
name eye turned out/in eye higher/lower
EN/ESO TROPIA; hyper/hypo TROPIA
define conjugate movement
parallel movements of the eyes in order to maintain focus on a moving object
define saccades
: rapid eye movements allowing rapid re-fixation of gaze from one object to another
define nystagmus
repetitive to-and-from movement of the eye
what are pendular nystagmus
when the two phases are of equal lengths
what are phasic/jerky nystagmus
slow movement to a limit of one direction by jerky movement in the opposite direction (described in relation of the first phase, can be horizontal or vertical)
what are causes of nystagmus
visual, vestibular, cerebellar and brain stem pathways
what are the P and M pathways in the cortex
P (ventral)= V2 (counter) V4 (colour and form) M(dorsal) = V3(global motion) V5 (motion)
define visual field
part of physical world from which source of light impinges on defined part of retina
define retinal field
piece of retina upon which light from external objects falls upon
What is the pathway of ocular reflex
CNII=> lateral geniculate nucleus=> pretectal nucleus=> (No Suggestions) nucleus=> CNIII=> pupil constriction
What is the pathway of corneal reflex
CNV1 => temporal and zygomatic of facial => orbicularis oculi
What is the pathway of vestibulo-ocular reflex
eye movement opposite to the head movement. Vestibular apparatus (movement detection)=>CNVIII=>CN of extraocular muscles
what is the problem with Mayer’s loop lesion how is it different to optic tract lesion
Homonymous Upper Quadrantanopia splitting of fibres in the optic tract it is homonymous hemianopia
What would be presentation and cause of right nasal hemianopia
diplopia, headache and nausea due to loss of vision in temporal retina e.g. due to cortex tumour
what is exophthalmos
Protrusion of the eye, causing the eyelids to part more than normal so that the whites of the sclera are visible all around the cornea and iris
what are the causes of exophthalmos
bilateral Graves; unilateral aneurism or haematoma
what signs of RICP can be seen in the eye
papilloedema
