Afferent Visual System Flashcards
Sudden vision loss can be caused by what 2 things?
- Vasculopathic
2. Chance Discovery
Progressive vision loss can be caused by what 3 things?
- Compressive
- Neoplastic
- Inflammatory
When visual loss is due to refractive error, amblyopia, media opacity, retinal lesion, ON or chiasmal lesion.. what system is affected?
Afferent visual system
What is the 1 exception to unilateral vision loss?
Amblyopia
An homonymous hemianopia is a lesion that present where?
Between chiasm and occipital cortex
If vision is reduced with a cataract, it will improve with ?
Improves with increased contrast
If vision is reduced with amblyopia, it improves with?
Improves with scotopic and single letter presentation
If vision is reduced with foveal disease, it improves with
improves with increased contrast
If vision is reduced by optic nerve disease, it improves with?
improves with increased contrast
What is the size of the central scotoma for these visual acuity?
a. 20/50
b. 20/100
20/200
a. ~ 5 deg (1.5-4.5)
b. ~ 10 deg (4-11)
c. ~20 deg (9-18)
If a patient can see 20/20, what should their stereopsis acuity be?
40’
The number on a dollar bill is what VA?
20/400
The wristwatch numbers are what VA?
20/40-20/50
If a patient does not improve with a pinhold, what’s the other causes of decreased VA?
- Central media opacity
- central scotoma
- Amblyopia
- Func. vision loss
- Pathology
In optic nerve disease, the color vision deficit will _____ the degree of visual loss
Equal
In retinal disease, VA is ____ effected than color vision
Va is more effected
If one’s VA is bad but color vision is good, what is the etiology?
Retinal
If one’s VA is good and color vision is bad, what is the etiology?
Congenital
If both the acuity and color vision are bad, what is the etiology?
Optic nerve
If the visual field defect equals the RAPD, what is the etiology?
Optic Nerve Disease
If the VF is greater than RAPD, this signifies what?
Significant retinal disease
If the visual field defect is less than the RAPD, what does this signify?
Inaccurate field
If there is a VF defect present and no RAPD, what does this mean?
Not optic nerve disease
The RAPD is not related to what?
Anisocoria
- it is assoiated with;
1. damage to afferent visual system
2. Asymmetric disease
An RAPD has a lesion where?
At or anterior to LGN ON/OC/OT)
What are the retinal causes of RAPD?
- CRAO
- CRVO
- RD
- Macular disease
What are the 5 causes of LND?
- Amaurotic eye
- Tonic pupil
- Argyll robertson
- Tectal/DMS
- Aber. Reg. of CN III
What are the subjective tests of afferent nerve functions?
- Brightness comparison
- Color vision/Desat
- Contrast Senstivity
- Visual Field
What 5 things to you focus on while assessing the optic disc?
- Edema
- Pallor
- Cupping
- Abnormal NFL
- Vessel abnormalities
