visual fields 2 Flashcards
scotoma
an area of partial or complete blindness surround by normal or relatively normal visual field
absolute scotoma
vision is entirely absent in the affected area
relative scotoma
some vision left in the affected area / there is blindness to some stimuli not others
positive scotoma
the person is aware that they are not seeing properly in a particular area
negative scotoma
the person isn’t aware that they are not seeing properly in a particular area
the HFA
threshold test
visual field plot
multiple stimulus test
henson
multiple stimulus is shown and px reports how many stimuli seen
advantages - more pateint friendly and faster
disadvantages - manual operation , can be more time consuming if defects present
suprathreshold screening
stimuli are presented slightly brighter than expected threshold.
advantages - faster and easier for px
disadvantages - may miss small defects and not good at monitoring change
what are some visual field defects
nasal step
temporal wedge
altitudinal
arcuate
paracentral
advanced glaucomatous
arcuate defect
its like a semi circle on the top half only but fades away a bit near the blind spot. so a full quarter and then half of the other superior quarter
paracentral defect
partial notch at the optic disk
mostly on nasal side
superior visual field projects to…
…inferior retina and inferior visual field projects to superior retina
nasal step
usually between inferior and superior nasal side. usually beginning of arcuate defect
temporal wedge
on temporal side near optic nerve on visual field plot
this means damage to nerve fibres on the nasal side of optic disc
altitudinal defect
half visual field is being affected inferior or superior
