Transcript Testing Visual Acuity in Nystagmus Patients

Pediatric Ophthalmology
 sub-specialty of ophthalmology
concerned with eye diseases, visual
development, and vision care in
children.
 Handle cases such as amblyopia,
starbismus, and nystagmus
Testing Visual Acuity in
Nystagmus Patients
TOBI OWOYEMI
DR. HEE-JUNG PARK
WILMER EYE INSTITUTE
Anatomy of Human Eye
What is Nystagmus: Background Information
 According to the American Association for Pediatric
Ophthalmology and Strabismus, Nystagmus is an
involuntary, shaking, “to and fro” movement of the
eyes
 Often congenital but can be acquired as an adult—
usually as a result of brain issues
 Can be caused by side effects of seizure medications
or disfunctions in the brain
What does a person with nystagmus actually see?
 Children with nystagmus typically see the world
similarly to other children, except with some
blurriness.
 The world does not appear to “shake”.
 They see the world in flashes at a time due to the fact
that their brain completely shuts down for less than
a millisecond
 Individuals with adult onset or acquired nystagmus
often report the appearance of movement of the seen
world (oscillopsia). Also, adults with nystagmus
usually have brain problems as well.
Why do people with nystagmus tilt
or turn their head?
 Nystagmus severity can vary upon direction of gaze;
the eyes oscillate more when looking in certain
directions.
 The gaze position of least eye movement is the “null
point” and tends to be where vision is best. Tilting or
turning the head can thus optimize vision.
Can surgery make nystagmus go away?
 Eye muscle surgery (strabismus surgery) may be
indicated for some individuals with nystagmus.
 The goal of surgery in most instances is to help
alleviate a significantly abnormal head position or to
decrease the amplitude of nystagmus.
 Surgery can sometimes cause vision improvement
but does not fully eliminate nystagmus.
What non-surgical treatments exist for
nystagmus?
 Significant refractive error is corrected with glasses
or contact lenses. Contact lenses, in some
circumstances, can be more visually beneficial than
spectacles.
 Variable success has been noted with medications
used to dampen the severity of nystagmus.
Unfortunately, the use of these medications is
frequently limited by side effects.
 Botulinum toxin is helpful for some individuals with
severe, intractable oscillopsia.
Purpose of Project
 Plenty of bias when testing visual acuity in
nystagmus patients– no good way of measuring
nystagmus that compensates for the nystagmus
 Use ATS or SVAT Ipad software?
 Ipad software is specialized for nystagmus patients,
ATS is not
 Test patients more effectively
SVAT Ipad Software
 Presents a staggered full
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field presentation of letters.
Representation dampens
nystagmus
When snapshot moment
occurs, they will be able to
see target in their flashes
Gets rid of need to try to
focus on something—helps
us see potential visual
acuity
Nystagmus gets worse with
fixation attempts
ATS (Standard Use of Measuring Visual Acuity)
 Requires patient to read
single letter at a time
 Distance of six meters
 Nystagmus gets worse
due to fixation attempts
 Patient is looking at
screen while doctor is
measuring visual acuity
Overview/ Questions Being Answered
 Use ATS or Ipad?
 Are we measuring visual acuity properly?
 Are the treatments for nystagmus effective?
 Can we modify visual acuity testing methods to
better capture potential visual acuity?
So, To Sum Things Up…
 In Pediatric Ophthalmology, Nystagmus is one of the
disorders that yield very little improvement
 We want to know why this is, is it because we are not
efficiently measuring visual acuity?