visual field Flashcards
What is the visual field?
what can be seen at a particular time without moving the head is the visual field
How can it be displayed?
By a perimeter for both eyes
What does the visual diagram display?
shows the peripheral vision for each eye and the central vision.
The information that reaches the visual cortex in the occipital lobe is not…
an exact replica of the visual field.
The image detected on the retina is upside down but…
becomes interpreted correctly in the brain
What reinforce the selected information and supress other information and why?
The retinal neuronal layers beyond the rods and cones
to enhance contrast
Which aspects are separated and projected in paralell pathways to different regions of cortex?
visual information like movement, colour and form
From which visual field does the right cortex receive information?
From the left visual field. Left side of cortex receives info from the right visual field
What can the visual field method be applied for?
for diagnosis of blindness in a specific portion of the retina
What are blind spots found in the field of vision called and what are the cause of them?
Scotomas, caused by damage to the optic nerve resulting from glaucoma, allergic reactions in retina or toxic conditions (lead poisoning /tobacco)
What causes the blind spot on the retina?
lack of rods and cones in the retina over the optic disc
How can you demonstrate blind regions in the retina?
By the test of Mariott
How many layers of exitable cells does the neural portion of the retina consist of?
3 layers:
- outermost layer closest to the choroid with rods and cones
- middle layer of bipolar cells
- inner layer of ganglion cells
The ganglions join to form?
The optic nerve –> leaves the retina slightly off centre (optic disc) –> refers to the blind spot
