What is it?
rhythmic oscillation of one or both eyes
What are the causes of nystagmus. Can be congenital or acquired.
Congenital- albinism/ retinal dystrophies
Acquired- intra-cranial lesions/drug toxicity
2 types of congenital nystagmus.
congenital idiopathic nystagmus ( CIN)- anomoly in motor pathway controlling fine eye movements
sensory deficit nystagmus (SDN) - anomly resulting in poor vision eg cataract, albinism, cone dystrophy, spasmus nutans ( self limiting)
** differentiated by fundus exam + electrodiagnositic techniques
features of congenital nystagmus
similar in both eyes
increase on occlusion
associated strabismus
Uniplanar horizontal waveform in all directions of gaze
how to manage congenital nystagmus in childhood
allow px to adopt AHP/CHP (compensatory head posture)
fog other eye during refraction. dont occlude ( worsens mvt)
fundus + VOLK
advise teachers of correct positioning of child in classroom - closer to front/ according to null position
surgery to reduce CHP ( wait till 8 yrs old)
use yorked prisms - base out RE, base in LE = versional mvt so eyes forced into null position. temporary before surgery bz uncomfortable to wear high power for so long
CLs- esp high Rx or eccentric null zone. px avoids looking thru spec lens edges.
What is the null zone?
posiion of gaze of least mvt
if not primary position = lead to CHP
CHP is in opposite position to null position
causes of acquired nystagmus
Mulitple sclerosis
cerebral vascular accident
menieres disease
tumours
head trauma
side effects of drugs
**presents with known onset and oscillopsia
management of acquired nystagmus
removal of tumour
drugs eg. Baclofen, alcohol & cannabis
surgery to null zone
BOTOX- limited success
What is the foveation period?
MLN
Last changed7 days ago
