Clutter, Fatigue and Fluctuating Vision: Untangling CVI in Children

September is Cerebral/Cortical Visual Impairment (CVI) Awareness Month, and Mays Dairi, M.D., says one problem sits at the center of how the condition is handled. Dairi, a professor of ophthalmology at Duke Eye Center who specializes in neuro-ophthalmology and pediatric ophthalmology and strabismus, said the field has a definition of CVI but no set criteria for diagnosing it.

CVI is vision loss that comes from the brain rather than the eyes. Dairi said conditions such as optic nerve hypoplasia are diagnosed by finding a specific, visible abnormality. CVI is instead identified through a list of behaviors, and the National Institutes of Health definition is so nonspecific that it has become a “catchall umbrella diagnosis.” As a result, general pediatricians and even pediatric ophthalmologists can miss mild or moderate CVI, or diagnose it while a larger, overlapping problem goes unaddressed.

Two cases where the label got in the way

Dairi shared two examples. In the first, a 10th-grader with developmental delays and an abnormal MRI read at a second-grade level. Eye exams over the years had been normal at times, but one showed vision of 20/800, and the teen was thought to be “acting up.” Dairi used a test designed for cognitive visual impairment in adults, since no pediatric version exists, and the patient demonstrated noticeable impairment. The school could then provide visual breaks and a less cluttered environment. The parents said no one had ever told them about the vision problem.

In the second case, a child struggling in school was steered toward neuropsychological testing after an optometrist raised concerns about cognitive issues. The testing produced a CVI diagnosis. By the time the child reached Dairi’s clinic, the child had optic atrophy caused by a vitamin deficiency that had gone untreated for a year.

How the brain learns to see

Dairi explained that the classic visual pathway taught in medical school, from the eye through the optic nerve to the occipital lobe, delivers lights, lines and shapes. It does not tell the brain what those shapes are. Infants gradually learn to recognize a parent’s face or a favorite toy, which is why books for 6-month-olds use a few high-contrast colors rather than a busy page.

In CVI, injury to the parts of the pathway that process what and where things are means children reach age-appropriate vision more slowly, or may never reach it. Because many of these children are nonverbal early on, clinicians must work out how they see. Dairi noted that few pediatric ophthalmologists have the time for that, and that assessment tools such as the CVI Range and other resources include elements that are not all evidence-based.

Clutter, fatigue and early clues

Children with mild to moderate CVI often see small, isolated objects but lose them in visual clutter. A child may spot a needle on a plain floor but not a favorite toy on a busy carpet. Parents frequently attribute this to tiredness or misbehavior. Dairi said the biggest early clue is a child who looks at something and then looks away because of visual fatigue.

In school, the pattern shows up as trouble recognizing items grouped together, difficulty with cursive and complicated fonts, and problems with glare or poor-quality copies. Dairi tells schools to assume a vision of roughly 20/100. A child may briefly reach 20/20 but cannot sustain it, so teachers should expect variability, allow breaks and simplify the visual environment.

A workup that takes time

Dairi said a proper evaluation takes an hour or more. Younger children are tested with finger foods or stickers placed on cluttered and plain backgrounds. Photos of a parent next to a celebrity can show whether a child recognizes family. Dairi disagrees with the claim that children with CVI do not recognize relatives, and believes the difficulty arises in crowds, not with faces.

Eye movements are also checked. Some children cannot move their eyes on command, a problem called oculomotor apraxia, and can be mislabeled with CVI. One such child was initially denied a wheelchair by an insurer that assumed CVI made the chair unusable, until it was clarified that the problem was eye movement. Dairi also performs an optical coherence tomography scan of the retina, which can reveal optic atrophy that a standard exam missed. In those cases, the environment must be enlarged and uncluttered.

What support can and cannot do

Dairi said vision therapy for CVI has not been proven to change outcomes. Its value, in Dairi’s view, lies in teaching parents how their child sees and in letting the child progress at a steady pace.

Dairi’s message this month is to seek a neuro-ophthalmic exam if in doubt, and not to rely on neuropsychological testing alone. CVI is a multidisciplinary diagnosis, and both eye specialists and other clinicians can get it wrong on their own. Families can also explore CVI Now, though Dairi cautioned that some behaviors it lists are not fully supported by evidence.