Block 12 Flashcards
(160 cards)
Involuntary rhythmic oscillation of 1 or both eyes
Nystagmus
Can be a sign of visual pathway lesion or an ocular control abnormality
Nystagmus
Type of waveform of nystagmus: has both quick and slow components
Jerk
Which way is the slow phase in a jerk nystagmus
Away from the target
Which way is the fast fast in jerk nystagmus
Back to fixation
How is jerk nystagmus characterized
Direction of fast phase
Type of waveform of nystagmus: to and fro movements of equal velocity in each direction
Pendualr
Type of waveform of nystagmus: doesn’t have a fast phase
Pendular
Which phase of jerk nystagmus reflects the abnormality
Slow
Slow movement to the right with a fast corrective jerk movement to the left
Left jerk nystagmus
The size/extent of the movement during nystagmus is known as the
Amplitude
From what 2 points in nystagmus is the amplitude measured
From the start of the drift away tot he start of the corrective movement
Number of oscillations per unit time in nystagmus
Frequency
Fast frequency nystagmus is how quick
> 2Hz
1 Hz equals
1cyc/sec
- a full rotation in 1 second
Frequency of a slow nystagmus is what time
<2Hz
- need a slit lamp to view
Where the intensity of the nystagmus diminishes and the VA improves
- may be associated with head position
Null point
With latent nystagmus seen with occlusion, the fast phase is towards
Uncovered eye
What does latent nystagmus usually indicated
A congenital condition
Anterior seg conditions with nystagmus (3)
Congenital cataract
Congenital glaucoma
Iridocorneal dysgenesis (didnt form properly)
Foveal condition associated with nystagmus
Foveal hypoplasia in albinism (flattening)
Optic nerve/retinal disorders associated with nystagmus
Coloboma of ON head (fissure doesn’t close)
ON hypoplasia
Toxoplasmosis
Do children with congenital nystagmus usually complain about issues
No
Nystagmus from motor coordination
Less VA loss (better VA)