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Motility Block 12 > Nystagmus > Flashcards

Nystagmus Flashcards

1
Q

Involuntary rhythmic oscillation of one or both eyes, can be a sign of visual pathway lesion or an ocular control abnormality

A

Nystagmus

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2
Q

Any abnormalities to any of these systems causes the eyes to drift and there is a need for saccadic re-fixation that results in nystagmus

A

Pursuits, saccades, optokinetic and vestibular

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3
Q

Nystagmus features and characteristics

A
  • type of waveform
  • direction of oscillation
  • amplitude and frequency
  • symmetry between the 2 eyes, if bilateral
  • constancy
  • any latent component
  • movement in all fields of gaze
  • ubiulteral or bilateral
  • conjugate or disconjugate
  • congenital or acquired
  • shaking, dancing, wobbling eyes, jerking
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4
Q

Is nystagmus voluntary

A

No

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5
Q

Jerk waveform in nystagmus

A

Have both quick and slow components. There is a fast corrective saccade to bring the eyes back to the target. Characterized by the direction of the fast component

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6
Q

Pendular waveform in nystagmus

A

To and fro movement of equal velocity in each direction (velocity of the beat same in each direction). A sinusoidal movement without a fast phase

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7
Q

What is jerk nystagmus characterized b y

A

The fast phase, but the slow phase of then ystagus reflects the abnormality

  • the eye drifts slowly from the target and there is a quick correcting saccade (fast phase) to return the fovea to the target
  • for instance, a left jerk nystagmus has a slow movement to the right and a fast corrective jerk movement to the left
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8
Q

Horizontal nystagmus

A

Side to side

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9
Q

Vertical nystagmus

A

Up and down

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10
Q

Torsional nystagmus

A

Rotary

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11
Q

Combination nystagmus

A

In any direction

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12
Q

Amplitude of nystagmus

A

The size/extend of movement between the start of the drift away from fixation to the start of the corrective movement (in the opposite direction)

  • basically, distance traveled during the movement
  • large nystagmus or small/fine nystagmus
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13
Q

Nystagmus frequency

A

Number of oscillations per unit of time

  • one hertz means a waveform completes a full rotations in 1s
  • the greater the number of beats, the higher the frequency
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14
Q

Frequency greater than _____ is fast

A

2Hz

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15
Q

Frequency les than _______ is slow

A

2Hz

Need slit lamp to view

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16
Q

Variation in field of gaze for nystagmus

A

The null point of a jerk ystagmus is where the intensity of the nystagmus diminished and VA improves. This may be associated with an anomalous head position

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17
Q

Chances with occlusion in nystagmus

A

Latent nystagmus

  • the fast phase is towards the uncovered eye; amplitude and frequency increase
  • latent component usually indicates a congenital condition
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18
Q

Other consideration in nystagmus

A

Variation in field of gaze
Changes with occlusion
Changes with visual demand

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19
Q

Most common type of nystagmus

A

Jerk

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20
Q

Etiology of nystagmus

A

Genetics
Developmental abnormalities
Ocular pathology.conditions

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21
Q

Anterior seg conditions associated with nystagmus

A

Congenital cataract
Congenital glaucoma
Iridocorneal dysgenesis

22
Q

Fovea hypoplasia and nystagmus

A

Very little fovea depression on OCT

23
Q

Null point in nystagmus

A

Where the jerk nystagmus slows down. VA improves at this point. This may be associated with an anomalous head position

24
Q

In changes with occlusion in latent nystagmus, the fast phase is towards the _________; amplitude and frequency increase

A

Uncovered eye

-latent component usually indicates a congenital condition

25
Changes with visual demand and nystagmus
Amplitude may decrease with convergence
26
Optic nerve disorders associated with nystagmus
Coloboma of the ONH Optic nerve hypoplasia Toxoplasmosis (retinal disorder)
27
Primary sensory retinal abnormalities associated with nystagmus
Leber congenital amourosis Achromatopsia Congenital stationary night blindness
28
Vitreoretinal abnormalities
Coloboma involving the macula Familial exudate vitreoretinapthy Retinal dysplasia Retinaoblastoma
29
Fovea hypoplasia and nystagmus
Albinism Aniridia Isolated
30
Infectious diseases and nystagmus
Congenital toxo Cytomegalovirus Rubella Syphillis
31
Eval of nystagmus
You will need to modify some of your testing to get adequate results for these patients. You will learn when and how to modify -proper eval necessary to differentiate between pathological and physiology nystagmus
32
Getting Hx for nystagmus
- onset - any associated conditions/events (infection, trauma) - variability and freqnwyc, amplitude, head positioning, null point, head nodding - symptoms: VA, asthenopia, blurred vision, diplopia, HA, vertigo, oscillopsia (is image shaking) - medical Hx: Dm, HTN, tumors, trauma - family Hx: any ocular or systemic - perinatal Hx: very important to get what mom did when pregnant or if premature
33
Children with congenital nystagmus
Seldom complain about problems -ask about neurological signs and symptoms -ask parents about head tilts/movements, gaze preferences
34
Obersevation in nystagmus
Observe position, head position, facial characteristics - since nystagmus could be better in certain gazes, tilts or turns - some characteristics I of nystagmus may be best seen under the slit lamp
35
VA and nystagmus
-varies
36
VA in nystagmus from motor coordination problems
Results in less Va loss than nystagmus from sensory issues, such as albinism, aniridia, or congenital cataracts
37
Marked decreased VA in nystagmus
Sensory, retina, and/or optics erve abnormalities
38
Nystagmus in patients with motor coordination disturbances
More of a cosmetic problem
39
Eval of VA in nystagmus
- eval VA in each eye at distance near, monocular and binocular, near vision can be better than distance vision - allow their preferred head position for the VA testing at distance and near. This is to assess true functional vision - preschool students may need the Allen symbols, lea symbols or matching HOTV - in younger children, assess their visual behavior by determining If there is an objection to occlusion
40
Monocular VA in nystagmus
One eye is covered, latent nystagmus may manifest- jerk nystagmus increases with the fast phase in the direction of the uncover the - need to eval VA without dissociated the eyes or use a plus lens to fog them (high enough plus lens to blur without breaking fusion) - if age appropriate, use the s Ellen chart, however, consider single letter or single line and not the full chart - VEP
41
Refractive error in nystagmus
- eval all nystagmus for this - correction could help - cycloplege to detect significant refractive error - patient should fixate in a gaze that offers best ocular stability during retinoscopy - use trial lenses of a lens bar
42
Bino vision and ocular motility in nystagmus
- move the eyes in 9 positions of gaze - eval pupil for PERRLA and the presence of an APD - moderate to large angels will be noticeabl and comitancy can be determined int he 9 positions of gaze - may be difficult to differntiate a small angel tropia and a phoria because of the Sonya NT nystagmus movement
43
Hirchberg and krimsky in nystagmus
Can be valuable to detainee if the corneal reflec appears symmetrical in both eyes
44
CT in nystagmus
Maybe difficult because it latent nystagmus-a +5.00 lens can be used in the place of a paddle in CT
45
Accommodation in nystagmus
This can be difficult because reduced VA causes a difficult seeing blur. MEM can be used
46
Sensory testing and nystagmus
Sterile and suppression testing is variable on these patients -stereo will allow you to determine if a patient has a phoria W4D Saccades nad pursuits
47
Ocular health and nystagmus
For IOP, try NCT or tonopen Consider Goldmann tonometry if the oscillation allows VF are difficult on these patients because of the change in fixation Interpret th results with causation
48
Slit lamp and nystagmus
To see the pattern of the nystagmus. If there is no cooperation, use a 20D of a hand held slit lamp -also important to detect the presence of iris coloboma or trans illumination
49
Dilation and nystagmus
Need dilation and complete eval of the retina and periphery. You may need to do eval at their null point to allow observation - rule out retinal, macular, or optic nerve abnormalities - photos
50
ERG in nystagmus
Could help identify Leber’s congenital retinal blindness -indicated if MRI is normal, fundus appears normal, but there is decreased VAS and nystagmus. An ERG can help ID retinal problems
51
More eval in nystagmus
- OCT fovea: to identify subtle fovea hypoplasia - eye movements eval: using infrared or video-based eye movement monitors for diagnostic an treatment purpose. Not routinely done in clinic - CT and MRI not done routinely, but indicated in acquired nystagmus, brain stems, cerebellar, or cortical lesions - recent onset or/and nystagmus that has not been diagnosed need neuro referrals

Motility Block 12 (4 decks)

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