What are the characteristics of
children with visual impairment in the
era without Dr. James E. Jan?
A review of the first 10 years since his
retirement.
Carey Matsuba, MD CM
Visual Impairment Program
BC Children’s Hospital
Sunny Hill Health Centre
Objectives
• To review criteria for visual impairment
• To discuss comment on the presentation
of visual impairment in children
• To review the common co-morbid
conditions associated with visual
impairment
• To discuss challenges in diagnosis
Background
• The Visual Impairment Program is in its 5th
decade of existence.
• Initially founded by Dr. James E. Jan, the
program offers consultative assessment
services to assist children and adolescents
with visual impairment throughout the
British Columbia and the Yukon.
James E. Jan
• Recognized that different
visual diagnoses were
associated with unique
characteristics.
• The following represents
the first 10 years of
children who presented
with visual impairment.
Methods
• In this period, 939 new patients were
referred for assessment of which 691
patients met criteria for visual impairment.
• The range of ages for the first assessment
was from birth to 16 years of age.
• Using this cohort, the distribution of visual
impairment and co-morbid characteristics
will be described.
Criteria of Visual Impairment
(Canada)
• Visual Impairment is defined as a
reduction in visual acuity or loss in visual
field.
• Most provinces use
– 20/70 or worse for low vision
– 20/200 or worse for blindness
– Less than 10 degrees from central fixation
Criteria for Visual Impairment
(ICD-10)
Category
Worse than
Equal to or better
0 Mild / No VI
6/18; 3/10; 20/70
1 Moderate
6/18; 3/10; 20/70
6/60; 1/10; 20/200
2 Severe
6/60; 1/10; 20/200
3/60; 1/20; 20/400
3 Blindness
3/60; 1/20; 20/400
1/60; 1/50; 20/1200
4 Blindness
1/60; 1/50; 20/1200
Light Perception
5 Blindness
9
No Light Perception
Undetermined or Unspecified
If the extent of the visual field loss is taken into account, patients with a field no
greater than 10 degrees, but greater than 5 degrees around central fixation should
be placed in category 3 and patients with a field no greater than 5 degrees around
central fixation should be placed in category 4, even if the central acuity is not impaired
Visual Impairment
NLP Blind
Visual Impairment
Normal Vision
Vision develops over time
• It relies on
– Opportunity
– Practice
– Experience – Interaction
– Development
Aetiology of Visual Impairment
DVM
CVI/CNS
ONA
ONH
Retinal
Structure
Nystagmus
Not VI Referrals
Age at Presentation (n = 691)
Age by Diagnosis
Other Visual Diagnosis
Nystagmus
Structure
Nystagmus
Structure
Retinal
Retinal
ONH
ONH
ONA
ONA
CVI
CVI/CNS
0
10
20
30
40
50
60
70
Diagnosis vs Severity
Low Vision
20/200 FC
LP / B
DVM
2
11
3
CVI/CNS
95
118
98
ONA
16
16
5
ONH
14
15
24
Retinal*
56
59
26
Structure
19
31
20
Nystagmus
38
24
0
*1 patient was not testable at assessment
At last follow-up (n = 507)
Not VI
Low Vision
20/200 FC
LP / B / (D)
DVM
4
3
1
0
(1)
CVI/CNS
30
76
76
40
(8)
ONA
7
9
7
5
(1)
ONH
8
9
15
8
(3)
Retinal
15
39
32
15
(2)
Structure
3
21
19
11
Nystagmus
10
21
7
0
(D) = died before follow-up assessment
An additional 3 patients moved out of the area
The acuity was not adjusted for age.
(1)
Hearing
Nystagmus
Structure
Retinal
ONH
Confirmed
Suspected
ONA
CVI/CNS
DVM
0
5
10
15
20
Cognitive
Nystagmus
Structure
Retinal
ONH
GDD / MR
LD / ASD
ONA
CVI/CNS
DVM
0
20
40
60
80
100
Motor
Nystagmus
Structure
Retinal
ONH
CP
Delayed
ONA
CVI/CNS
DVM
0
20
40
60
80
Seizures
Seizures
Nystagmus
Structure
Retinal
ONH
Seizures
ONA
CVI/CNS
DVM
0
20
40
60
80
Challenges
• Cortical Visual Impairment
• Retinal Abnormalities
• Function
Cortical Visual Impairment
• Dr. Jan described patients with CVI
– Reduction in visual acuity that could not be
explained by anterior pathway disease
– Physiological reason for an impairment – the
aetiology for bilateral occipital pathology;
identified by imaging and/or
electrophysiological studies
– Clinical characteristics – light gazing, colour
preference, variability in visual attention
Can you have CVI without
clinical characteristics?
Maybe…
• A patient with isolated (focal) bilateral
occipital damage (eg infarction) may
present with a reduction in visual acuity
without the clinical characteristics of CVI
• These patients are more in keeping with
“cortical blindness”.
Retinal Dystrophies
• There hundreds of different aetiologic
conditions that can lead to retinal
dystrophies.
• The clinical presentation can be quite
variable; as a result some will have a
reduction in visual acuity in the first
decade, while others may be clinical
asymptomatic until well into adulthood.
When should you be
diagnosed with visual
impairment in retinal
dystrophy?
Trends in Diagnosis
• Over the past decade, our program has
had a number of referrals as a result of
abnormalities in the fundi exam and an
abnormal ERG; but normal or near normal
visual acuity
• The patients in the past would not have
presented until they were symptomatic.
Challenges in the context of
“normal” or “near normal acuity”
• Inability to predict course of the condition,
even if there is a family history
• The importance of using vision to
understand concepts vs the introduction of
non-visual strategies
Should we consider function in
the diagnosis of visual
impairment?
Pros
• Represents how a person uses their vision
in the context of the individual’s skill within
the environment
Cons
• Everyone can have functional difficulties
• Function is highly dependent on ability,
familiarity, perspective.
• There is no clear measure to determine
“functional visual difficulties”. For example,
some would consider dyslexia as
functional difficulty
Conclusions
• The epidemiological features of childhood
visual impairment has remain similar over
the past decade.
• There has been some new challenges in
the diagnosis of visual impairment that
needs further discussion
Questions
Contact:
cmatsuba@cw.bc.ca