Cerebral Visual Impairment (CVI), also known as cortical visual impairment, is a prevalent condition affecting children, often associated with neurodevelopmental disorders or complex disabilities. However, CVI can also occur in children with typical development, presenting a spectrum of visual acuity from normal to severely impaired. Effective identification of CVI necessitates a comprehensive visual performance evaluation beyond standard high-contrast acuity tests, acknowledging the fluctuating nature of visual function in affected individuals. Historically, CVI has received limited attention in ophthalmology training, leading to a knowledge gap among professionals. This has resulted in inconsistent detection and diagnosis across regions, causing varied experiences for patients and their families.
This article provides a detailed overview of current research and clinical approaches for diagnosing CVI in pediatric ophthalmology settings. It reflects the latest understanding in this evolving field, incorporating insights reviewed by the UK CVI specialist interest group. This guide addresses crucial questions surrounding CVI diagnosis, aiming to equip healthcare professionals with the knowledge for accurate identification and effective management.
Understanding Cerebral Visual Impairment
Cerebral Visual Impairment (CVI) is an encompassing term for a wide array of vision problems originating in the brain, not the eyes themselves. It stands as the leading cause of visual impairment in children across developed nations. While a general agreement exists regarding the characteristics of CVI – visual difficulties not explained by ocular issues – definitive diagnostic criteria and thresholds are still under development.
Varied perspectives exist within the medical community; some consider impaired visual acuity or visual field (not due to eye or optic nerve pathology) as essential for CVI diagnosis, while others adopt a broader view, encompassing any brain-related visual deficit as potentially CVI. For this discussion, we embrace the more inclusive definition, pending the establishment of universal diagnostic guidelines.
Currently, there is often no cure for CVI. Instead, management focuses on mitigating the impact of visual dysfunction. This is achieved through personalized strategies and environmental modifications tailored to each child’s unique set of visual challenges.
Current Consensus Definition of CVI
Based on established research, the current consensus definition of CVI is:
A verifiable visual dysfunction that cannot be directly attributed to disorders of the anterior visual pathways or any co-occurring ocular impairment.
The diagnosis of CVI relies on expert clinical judgment, acknowledging that assessment methodologies and individual interpretations may differ across practices. Ongoing efforts, such as those by a European multidisciplinary group, are dedicated to establishing standardized diagnostic criteria through systematic reviews and professional surveys. Despite the lack of universal criteria, established protocols and pathways offer valuable guidance for pediatric ophthalmology services in assessing children suspected of having CVI.
Epidemiology of Cortical Visual Impairment
Cerebral Visual Impairment is the most frequent cause of registered visual impairment in the UK. Reports indicate that CVI affects a significant proportion (20–90%) of children diagnosed with common neurodevelopmental conditions, including prematurity, cerebral palsy, hypoxic-ischemic encephalopathy, hydrocephalus, meningitis, and Down syndrome. Children with special educational needs are significantly more vulnerable, being 28 times more likely to experience vision problems compared to typically developing children. The CVI Project has revealed that approximately 3% of children in mainstream schools – about one child per classroom – experience CVI-related visual difficulties. This prevalence positions CVI alongside amblyopia as a common visual disorder in childhood.
Children with CVI often present with varying profiles:
- Children with significant developmental delays and impaired visual acuity, along with other fluctuating visual deficits.
- Children with minimal or no developmental delay, near-normal or normal visual acuity, but with impaired oculomotor and visual processing skills.
- Children exhibiting a mix of characteristics from both profiles.
- An emerging fourth group includes children who functioned well and appeared asymptomatic until experiencing a point of decompensation.
Regardless of their specific profile, all children with CVI face substantial visual difficulties impacting their daily lives, educational progress, and independence.
The Ophthalmologist’s Crucial Role in CVI Identification and Diagnosis
Ophthalmologists are pivotal in addressing concerns about visual development raised by parents, educators, and healthcare professionals. Their role includes providing timely and accurate diagnoses, enabling children to access necessary services and support.
Figure 1: Diagnostic pathway for pediatric cortical visual impairment, highlighting the stepwise approach.
Existing services may employ different approaches, and collaborative efforts among pediatric ophthalmology, developmental support services, and education sectors are essential to refine local protocols.
Figure 2: The multidisciplinary team crucial for supporting a child diagnosed with Cortical Visual Impairment, showing the network of agencies involved.
While defining a specific model of care is beyond this document’s scope, a general pediatric ophthalmology department is expected to contribute to CVI diagnosis by:
- Ruling out or managing any co-existing ocular conditions, such as optic disc anomalies, structural issues like cataracts or coloboma, refractive errors, and accommodation dysfunction.
- Gathering patient history to identify risk factors and symptoms of CVI, facilitating proactive detection of visual dysfunction or indicative behaviors.
- Collaborating with the broader healthcare team, especially pediatric and developmental disability specialists, to ascertain associated conditions.
Diagnostic Process for Cerebral Visual Impairment
Diagnosing CVI involves three primary components, as detailed in Tables 1 and 2. A positive finding in all three areas strongly suggests the presence of CVI. Positive findings in two out of three elements should raise suspicion and prompt further investigation, gathering more evidence from parents or other professionals to confirm or rule out a CVI diagnosis.
Table 1: Core Elements in Cortical Visual Impairment Diagnosis
| Diagnostic Element | Description
