Bv Lec 12 Flashcards
What’s nystagmus
Rhythmic oscillation if eyes about one or more of its visual axis
NOT A DIAGNOSIS ON ITS OWN BUT A SIGN ID NEUROLOGICAL ANOMALY
Differential diagnosis for nystagmus
Opsoclonus
Superior oblique myokymia
Akinetopisa
Visual allesthesia
What are the 3 types of physiological nystagmus (not a disease)
End point nystagmus
Post rotational nystagmus
Voluntary nystagmus
How is pathological nystagmus classified
Onset (congenital/acquired)
Waveform (jerk/pendular)
Cause (cerebellar/labyrinthine)
What are jerk and pendular nystagmus
Jerk - slow drift then a fast corrective phase
Pendular - sinusoidal oscillations and approx equal amplitude/velocity
What an example of congenital nystagmus
Low vision nystagmus
-lack of fixation reflex secondary to neonatal blindness
- pure pendular (rare)
- pendular changes to jerk in versions (majority)
-no AHP
What’s sensory nystagmus
Any disease that results in bilateral neonatal blindness
E.g cataract/opacity/ONH atrophy or hypoplasia, retinal disorder
Albinism is a common cause of low vision in young px
What’s the symptoms &
mechanism behind it
Reduced VA from fovea hypoplasia
Strabismus from abnormal decussation of ocular fibres (20% temp fibres decussate at chiasm)
Photophobia from iris transillumination
What is idiopathic nystagmus
All types of manifest nystagmus without a primary visual defect at birth or in first weeks of life as visual fixation develops
Hereditary and often irregular Xlinked dominant disorder
First 5 Signs of idiopathic nystagmus
Develops early infancy
Bilateral horizontal and equal amp
Pendular initially but becomes jerk
Null point so has AHP?
Dampens on convergence
Last 4 signs of idiopathic nystagmus
Latent so increases amp on monocular view
Movements abolished in sleep
Oscillopsia rare
Reversed OKN response
Whats latent nystagmus
Horizontal jerk nystagmus present when light stimulus to either eye reduced
No observable nystagmus when eye is uncovered and light in BEs
What’s manifest latent nystagmus
Horizontal nystagmus present when BEs open but increases in amp when one eye covered
Associated with infantile esotropia