Vision Flashcards
Cones
– color – requires more light
Rods
– black & white – not as light sensitive
Visual acuity
– clarity of what see – can change over time – near sighted/far sighted
Visual fields
– gives panoramic view
Accommodation
– helps focus in on object coming closer to you
Fixation
– being able to have gaze remains fixed on object
Pursuit
– following something moving
Saccades
– ability to scan, to be able to watch something – scan one object over another
Convergence
– ability for eyes to come in together (cross eyed)
Binocularity
– the integration of accommodation & convergence
Stereopsis
– depth perception – know where are in relation to objects
Anosognosia
– can’t identify something
The Visual System
Consists of two systems:
- Anterior Visual System
- All structures anterior to the optic chiasm
- Provide high-quality, accurate visual sensory input
- Posterior Visual System
- All structures posterior to the optic chiasm
- Transfers information from anterior system to posterior system components for processing, interpretation, and utilization for additional neural processes
Anatomy of the Eye
- Light goes to retina
- Lens can change shapes to refract light – cilliary bodies in it that help change the shape of the lens
- Macula – sensitive spot in retina – responsible for detailed vision (a lot of cones) – part of macula is called phobia
Posterior Visual System
- Optic Nerve, Optic chiasm & Tracts
- Lateral Geniculate Nucleus of thalamus
- Superior Colliculi of midbrain
- Visual Cortex in Occipital Lobe
- Primary visual cortex
- Visual association cortices
Visual Cranial Nerves
3 – occulomotor – up & down
4 - Trochlear – lateral & down
6 - lateral
Visual Acuity
- Normal Vision
- Normal – read 8 point at 40 cm
- Near normal – read newsprint by bringing close
- Low Vision
- Moderate – very close to read, can read with glasses
- Severe – can read very close with difficulty, avoids activity
- Profound – reading limited without magnification
- Blindness
- Near Blindness – vision unreliable- uses other senses
- Total blindness – no vision
Hyperopia
- Far sighted – can see far away, can’t see close up
Myopia
- Near sighted – can see
Astigmatism
– combo of two
Vestibulo-Ocular Reflex
Head moves RIGHT
Eyes move to the LEFT
Visual field deficits
- Controlateral homonymous hemianopsia
- Loss of visual field on opposite side of brain lesion
- Lesion to optic tract
- Bitemporal hemianopsia (tunnel vision)
- Temporal fields in both eyes lost
- Lesion to central optic chiasm
- Blindness unilateral
- Ipsilateral optic tract lesion
- Blindness bilateral
- Lesion to entire optic chiasm
- Blind spot
- Retinal damage
- Cortical blindness
- Visual cortex damage
Visual field
Temporal field – nasal nerve - crosses
Nasal field – temporal nerve – doesn’t cross
Diplopia
double vision
Strabismus
Medial or lateral deviation
Glaucoma
- Pressure builds up in eye
- It can’t drain properly
Macular Degeneration
- Can be common
- Can lead to blindness (leading for blindness of those over 55 y-o)
- Deterioration of vision
- Can’t focus well
Visual Agnosia
-Can copy but cannot name or describe the function
