Parents of children
with cortical visual impairment deserve more of an
explanation of their child’s condition than, “The eye examination is
normal. No glasses are necessary.” In the past, eye-care providers,
including ophthalmologists, were often uncomfortable when dealing with
the patient and family with a complex set of challenges. There was a
perceived dismal prognosis with no hope of recovery. Cortical visual
impairment, which is already the most common cause of vision loss in
children in developed countries, will increase in incidence as medical
technology and research continue to improve survival.1
information and more tools can assist the ophthalmologist in providing
patients with care.
Definition & Characteristics
visual impairment is defined as bilateral visual impairment, involving
acuity and/or higher visual functions, such as visual motor planning,
due to posterior visual pathway disease. It is one component of a global
Patients with cortical visual impairment often
display characteristic behaviors that may improve or resolve as the
child improves. These characteristics include: light gazing;
photophobia; poor visual attention; preferences for certain colors;
visual field abnormalities; difficulty with visual complexity; problems
with viewing distance; eccentric viewing; atypical visual reflex
behaviors; and variability with contrast.2
These characteristics may
resolve as a patient improves. A detailed history may reveal previously
|Figure 1. Axial CT scan illustrating hydrocephalus with volume loss and damage to optic pathways resulting in cortical visual impairment.
Sean P. Donahue, MD, PhD, and
colleagues have demonstrated that the most common causes of cortical
visual impairment in children are perinatal hypoxia, prematurity and
Other etiologies in children and adults include:
traumatic brain injury; stroke; congenital anomalies; central nervous
system infections; neonatal hypoglycemia; and seizures.4
patients may have co-morbidities and associated deficits that make the
identification, evaluation, treatment and rehabilitation of the patient
more difficult. R. Michael Siatkowski, MD, and colleagues have shown
that premature infants are particularly vulnerable to anterior and
posterior visual pathway disease, which may complicate the
identification of the cause of vision loss.5
A. Goodale, PhD, and A. David Milner, PhD, described the two-stream
hypothesis of neural processing in 1999. Information concerning
recognition of objects travels from the occipital cortex to the inferior
temporal cortex (ventral stream). Information concerning the location
of objects and control of movements to locate objects in space travels
from the occipital lobe to the parietal lobe (dorsal stream).6
Pathophysiology affecting the ventral stream may cause difficulty with
object and facial recognition. Pathophysiology of the dorsal stream may
cause difficulty locating objects and visual motor planning (visual
guidance of movements).
Originally, it was thought that these two
systems were separate entities; however, more recent research indicates
that processing of complex visual information requires connections
between the ventral and dorsal streams.7
Classroom learning is
largely vision-based. Both ventral and dorsal stream pathology may
hinder educational progress, unless accommodations and interventions are
made. Activities of daily living are also highly dependent on vision. A
child’s independence in routine activities may also be affected and
require deficit- based compensation.
|Table 1. CVI Internet Resources
Periventricular leukomalacia and
perinatal stroke make premature infants particularly vulnerable to
visual pathway damage, resulting in the previously described typical
visual characteristics associated with cortical visual impairment.
Visual performance often mirrors the global neurologic deficit. More
severely affected patients with quadriplegic cerebral palsy often have
more limited visual performance. Patients with diplegic cerebral palsy
may have better visual acuity and performance but may demonstrate visual
field deficits and higher-level function deficits.
Classification and Prognosis
Roman-Lantzy, PhD, has described a spectrum of phases that correlate
with the severity of visual characteristics displayed by a patient with
cortical visual impairment. Phase I is the lowest level of function,
where a patient displays minimal visual responses. Phase II is a higher
level where visual performance is linked to improved function. Phase III
is the highest level of performance, where some typical characteristics
may become extinct.8
Patients may progress from one phase to another
with improvement in function. This type of classification provides a
common language for families and the multidisciplinary team caring for a
child. It is also the basis for providing interventions and
accommodations that may be used to assist a patient with cortical visual
impairment in the educational setting and with activities of daily
In the past, cortical visual impairment was called cortical
“blindness,” with a perceived poor prognosis. Although some patients may
not have any improvement, studies have shown that the majority of
patients have at least some improvement in vision.9
It is important to
communicate this fact to families when the diagnosis of cortical visual
impairment is made.
It is important to educate families as well as
other health-care providers who may treat children with cortical visual
impairment in order to prevent inaccurately poor prognostic predictions.
Baseline visual acuity at diagnosis cannot be used to predict final
visual performance. The degree of damage demonstrated on brain imaging
studies cannot be used to predict final visual performance either.
The Ophthalmologist’s Role
The ophthalmologist is an important member of the multidisciplinary team that cares for a child with cortical visual impairment.
the history taking, it is important to solicit observations of visual
performance from the family and other members of the child’s care team. A
child’s performance in a limited examination time, in an unfamiliar
place when he may be tired and hungry, may not be representative of true
function. It is often the occupational or physical therapist who first
notes a visual field defect in a patient.
|Baseline visual acuity at diagnosis cannot be used to predict final visual performance. The degree of damage demonstrated on brain imaging studies cannot be used to predict final visual performance either.
A full ophthalmologic
examination, including cycloplegic refraction, should be performed in
order to assess visual acuity, look for characteristics of cortical
visual impairment, and identify the presence of clinically significant
ocular conditions. Visual performance can be maximized by treating any
ocular co-morbidities, including any significant refractive errors.
Dynamic retinoscopy is a useful tool to evaluate for accommodative
It is vital for the ophthalmologist to make and
document the diagnosis of cortical visual impairment, as well as reduced
visual acuity, if present. Patients may qualify for services based on
the level of visual impairment, especially if a patient has a chronic
visual condition that will impair educational progress. Further
assistance for interventions or accommodations that may help a patient
reach his or her full potential depends on the diagnosis made by the
When appropriate, a referral for an evaluation for
vision services from the appropriate agency should be made. The referral
for infants and children prior to the third birthday can be made
through their early intervention program or appropriate state agency,
depending upon the patient’s state of residence. The referral for
children age 3 and older is made through the school district or
appropriate state agency.
The findings of the eye examination and
diagnosis should be discussed with the family. Educational and resource
materials should be provided. It is important to provide a list of
websites with accurate information appropriate for the patient’s
diagnosis, since many families primarily use the Internet for medical
information. It is also helpful to have pre-printed information ready to
give families whose child has a common diagnosis.
recommendations for treatment, interventions and accommodations should
be discussed with families, documented and given to families in writing
as part of the discharge instructions.
interventions and accommodations should be based on the patient’s level
of function and characteristics of impairment present. Suggestions for a
low-functioning, 6-month-old, former preemie with periventricular
leukomalacia and hypotonia in Phase I may include:
1. High-contrast, lighted and moving visual stimuli;
2. Avoid overstimulation;
3. Provide support for body when performing visual tasks;
4. Allow extra time for response to visual stimuli; and
5. Use auditory and tactile cues to attract and sustain visual attention.
Suggestions for a higher-functioning, school-age child with cerebral palsy in Phase III may include:
1. Allow extra time for response to visual stimuli because of processing and expressive delay;
2. Limit complexity and increase as tolerated;
3. Avoid graphite pencil on recycled paper;
4. Use black marker on white paper for written activities; and
5. Exploit auditory learning skills.
with a disability that interferes with educational progress who attend
school accepting federal funds may qualify for an individualized
educational plan, or IEP, under the Individuals with Disabilities
Education Act (See
.) It is important to document these needs
and communicate appropriately with the family and other members of the
child’s multidisciplinary team.
It is imperative for the
ophthalmologist to be an active and involved member of the team caring
for a child with cortical visual impairment. The ophthalmologist should
provide diagnoses, referrals for services, treatment of ocular
co-morbidities, education and advocacy for the patient. Interventions
and accommodations allow the child with cortical visual impairment to
attain his or her fullest educational potential and maximize
independence in activities of daily living. REVIEW
Dr. Lehman is
the chief of ophthalmology at Nemours/AI duPont Hospital for Children,
Wilmington, and a clinical professor of ophthalmology and pediatrics at
Jefferson Medical College/Wills Eye Institute, Philadelphia.
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