Vision loss happens in a variety of types. Some people lose their peripheral vision, some may suffer from central vision loss, while some may see smudges in their field of view. However, partial eyesight loss is not the only form of visual impairment. There is a vision problem related to the brain which will cause trouble with literacy. This brain-related visual impairment is common in children and the process of diagnosis and treatment is complicated. The read aims to introduce this vision problem in order to help more kids get early intervention.
What is CVI?
CVI, the abbreviation of cerebral visual impairment, also known as cortical visual impairment, is a brain-related visual problem that occurs frequently in children. Unlike the regular ocular issues, CVI is neurologically related. Usually, the lights will reflect on the brain through our eyes, and then a specific area of our brain will handle these signals so that we are able to understand what we see. However, CVI indicates that the connection between the eyes and the brain cannot work well. The eyes seem to be good but the internal area in the brain couldn’t interpret the signals anymore.
The causes of CVI often happen before, during or soon after birth the majority of the time, which means this disease may be congenital or required. The common causes of CVI in babies or children might include:
- Inadequate blood flow or oxygen to the brain (because of pediatric stroke, hypoxic-ischemic encephalopathy in infants or other situations)
- Neonatal infection (viruses that enter the brain)
- Metabolic disorders
- Severe epilepsy
- Genetic factors
- Developmental deficiency of the central nervous system
The causes of CVI mentioned above are more prevalent in premature infants, so babies and young children are more likely to suffer from CVI, and the disease can possibly last until adulthood. Besides these situations, CVI can be caused by some special diseases such as autism, cerebral palsy or severe mental retardation. Many researches show that CVI affects up to 70% of children with cerebral palsy. Furthermore, the health condition of the mothers when they are pregnant could affect if their babies would have CVI as well, especially the use of prenatal medication.
The traumatic head injury needs to be explained particularly as it can cause CVI in whether children or adults. Due to the principle of CVI, external damage to the head might hurt the specific area of managing vision interpretation in the brain, which would result in cortical visual impairment eventually. In this case, adults thus acquire the possibility of developing CVI as well, and combat-related injuries may put veterans at a higher risk for this visual issue. Meanwhile, to avoid CVI caused by brain injury in infants, it should be alert of shaken baby syndrome or accidental head injury to the kids.
The diagnosis of CVI is complex and it requires both eye exams and brain exams. Checking the situation of the eyes is the preliminary step to confirm the eye function is in good condition. If there is nothing wrong with the eyes and the vision, then the scanning of the brain might be the next stage to examine deeply. Considering the likely complications that come with CVI, the disease sometimes is barely diagnosed and managed. In this case, the patient may particularly need a doctor who is really familiar with CVI.
What are the Symptoms of CVI?
CVI symptoms are much more complicated than other vision issues. Unlike the symptoms of other eye disorders with eyesight loss, the influences of CVI could demonstrate more on the behaviors of the patients. The possible symptoms of people with CVI could be as the following:
- Couldn’t react or react very slowly to the visual information
- Couldn’t identify objects or people’s faces
- Couldn’t distinguish things in congested places
- Couldn’t understand things they are seeing
- Couldn’t look others’ eyes or avoid others’ gaze
- Like to stare at the lights or show the opposite: being sensitive to the lights
- Like using their peripheral vision to observe
- Like to watch things that keep moving
- Like to see colorful objects more than monochromatic ones
- Like to try to get what they are seeing
- Other health issues: hearing loss, growth retardation and so on
Generally speaking, the symptoms of CVI conclude the aspects of behavior, vision and health. They can be hard to summarize specifically when CVI is accompanied by other diseases like cerebral palsy. Moreover, a concept that is often referred to with CVI is literacy difficulty. It’s an obvious manifestation of CVI as well. People with CVI acquire literacy difficulty since they cannot handle the reading and writing process, just like the above-mentioned symptoms. The literacy difficulty of CVI has a major impact on people’s daily life, and it’s the key to treating the disease for the children.
What’s the Treatment of CVI?
Unfortunately, there is no cure for CVI with modern medical measures, whereas the symptoms can be changed or relieved as the patients grow up since the disease is more prevalent in young children. For those infants and young children who have CVI, the early intervention is crucial for helping them learn and live. Many hospitals, institutions, or organizations offer relevant resources and help for those with CVI. Usually, the treatment would focus on training the literacy of the patients, assisting them to recover vision function as much as possible. To know more about literacy materials for kids with CVI, please check: https://www.pathstoliteracy.org/resource/cvi-literacy-awareness-month/
There are some indicators to describe the situation of the patient when developing the treatment or intervention for the kids with CVI. According to different severity of visual functions with CVI, Dr. Christine Roman-Lantzy gives 10 CVI characteristics to recognize the situation, which includes color preferences, movement, visual latency, visual field, visual complexity (array, target, faces, sensory), attraction to light, distance-viewing, visual reflexes, visual novelty, and visually guided reach. These 10 CVI characteristics consist of an important part to assess the CVI phases:
- Phase I: Impact on the visual function that is the most severe
- Phase II: Mild effect on visual functionality
- Phase III: Visual performance is most similar to normal
The experts might arrange proper treatment following CVI phases, as the situation of the patients varies at each phase.
Cerebral visual impairment truly is a serious problem in children as it’s the leading cause of vision issues. Differing from typical visually impaired children, the issues in the brain make the disease more difficult to diagnose or treat. CVI can happen frequently in many developed countries and it brings huge inconvenience to a lot of families. Therefore, April has been defined as CVI Literacy Awareness Month, aiming to raise the cognition of this brain-related disease. Improving the comprehension of the needs of children with CVI at different phases is also essential. What we are trying to do in CVI Literacy Awareness Month is to spread the knowledge and call on more people to devote to helping children with CVI.
References:
https://www.childrenshospital.org/conditions/cortical-visual-impairment
