by Dan Roberts
Waiting until late childhood to provide vision correction could cause permanent brain dysfunction and life-long psychological disorders.
The majority of people are dependent upon their eyes for the largest part of their sensory input. As much as 80% of sensory input is afforded by vision, and the brain devotes about 35% of itself to process that input.(1) But what problems might children encounter who are visually deficient from birth through their formative years, who never develop the level of visual dependency of a fully-sighted child, and who then finally receive correction providing normal or near-normal vision? “Delayed vision correction” (DVC) will be used here to identify this small, but important population.
By the time the eyesight of a DVC child is corrected, nature will have altered the functional and structural organization of the child’s brain to allow other senses to play a more important role in processing input.(2) This physiological process is called compensatory plasticity, an hypothesis which has been supported by data from functional MRI studies.(3) With eyesight taking a back seat, the child may, therefore, become more dependent upon gustatory, auditory, olfactory and tactile stimuli than upon eyesight. This altered sensory balance can manifest itself in various ways:
- Hypersensitivity to physical stimuli
- Need for tight control of the environment
- Poor visual observation skills (eg. recall of faces, attire, and landmarks)
- Unusually good aural discrimination (eg. timbre and pitch)
- Low level spatial awareness
- Gaze avoidance (4)
Such characteristics are shared by many people who have no useable eyesight due to permanent damage or underdevelopment of the visual system. Delaying vision, therefore, risks creating an interesting type of individual who has usable eyesight, but who functions as a blind person. In effect, this describes cortical vision impairment (CVI), a disability resulting from either an insult to the brain or how the brain organization becomes configured during prenatal development.(5)
Christine Roman-Lantzy, Ph.D. describes it this way:
“CVI is an issue of deprivation. Kids with CVI see the world. The information [goes] into their eye and passes through the front part of the visual system [the retina] to the back part of the visual system [the visual cortex], which is usually where CVI exists. But obviously something goes very wrong due to lots of different causes. Kids with CVI theoretically see, but they can’t interpret what they see, and they see the world . . . as kind of a kaleidoscope of meaningless colorful color and pattern.”(6)
Two Case Histories
Mike May, the subject of Robert Kurson’s book, Crashing Through,(7) is a familiar example of CVI. Blinded by a chemical explosion at the age of three, May lived with only light/dark response for more than four decades before his vision in one eye was restored to normal by corneal stem cell transplantation. His visual cortex was, however, still permanently affected by deprivation of visual input during his formative years. He had regained eyesight, but he remained cortically underdeveloped—a condition which might be called “acquired” cortical vision impairment (ACVI) in order to differentiate it from the syndrome’s prenatal pathology. Recognition of this variance has been validated by Roman-Lantzy as “a legitimate possibility” (based upon early studies by Wiesel and Hubel)(8) showing that “deprivation can forever [alter] the visual cortex, affecting a child’s ability to see the same way other children do”.(9)
A more common case is that of “Lee” (not his real name), who, like May, was born with a supposed healthy visual system. In Lee’s case, however, ACVI developed as a result of poor visual input over nine years. Not having been diagnosed and corrected for high myopia until the age of nine, he unconsciously developed heightened non visual senses during his brain’s most important development period. After receiving bilateral correction with glasses from about 20/100 to 20/20, Lee’s eyesight normalized, but he began displaying new and disturbing behaviors, to include hoarding, withdrawal, phobias, compulsiveness, obsessiveness, and anti-socialism.
By the time he was an adult, Lee had developed, both consciously and unconsciously, coping mechanisms that led him to seek employment and activities in which he could control his environment, i.e. managerial positions and solitary recreational pursuits. This served him well, but eventually, out of curiosity about his self-perceived unusual behavior, he sought private psychotherapy. The therapist concluded that Lee’s behaviors appeared to stem from sensory overstimulation, but a clear pathology and diagnosis was still out of reach.
It was not until several years later that Lee read about CVI and saw strong similarities with his symptoms. Remembering his own experience and realizing that his behaviors had begun at the time he was first fitted with corrective lenses, it was an almost too easy connection to make. He said, “When I first put those glasses on, I could see better, but I always felt like a bird out of its cage after that, and I didn’t know why. My self-diagnosis of ACVI was a perfect fit.”
Symptoms of ACVI
Lee’s symptoms exist abundantly in CVI children. Terese Pawletko, Ph.D. et al listed and compared symptoms of CVI and compared them with autism spectrum disorder. They shed light on undeniable parallels in the areas of socialization, language, communication, perseverative or narrowly focused interests, and hypo- and hyper-sensory systems.(10) It is understandable to confuse various manifestations of autism with those of CVI, and, by extension, those of other like syndromes, such as:
- anxiety disorder
- clinical depression
- Asperger syndrome
- obsessive-compulsive disorder (OCD)
- dysfunction of sensory integration (DSI)
- bi-polar disorder
Many ACVI children may be unwittingly labeled with wrong diagnoses. Researchers at the Ratner Children’s Eye Center in San Diego discovered that children with convergence insufficiency (inability to maintain proper binocular eye alignment) are three times as likely to be diagnosed with ADHD than children without the disorder.(11) Additionally, 21 to 50 percent of the autistic population is affected by strabismus, compared to 3-4 percent of the normal population.(12)
Recovery From ACVI
Sudden vision correction may lead to sensory overload in an ACVI child, but might the problem resolve over time? A study in 2006 at the Massachusetts Institute of Technology(13) suggested that the visual cortex of the human brain can retain its ability to learn new functions later in childhood. Researchers found that a 32-year-old woman whose sight was restored at age 12 showed normal or near normal abilities on most tests of high-level vision. Interestingly, the researchers also found that she had difficulty visualizing objects with her eyes closed, and she would define a person’s gaze by which way his head was pointed, rather than by the direction he was looking. This case suggests that CVI might partially recover after a delay of as long as 12 years, but that the sense of sight may play a lesser role.
Other research has demonstrated recovery of visual response in the occipital lobes of canines with genetically restored retinal function.(14) Responses to light within the visual cortex increased dramatically, which is encouraging for humans who become impaired after their developmental years. What, however, might be the psychological cost for DVC people who are rescued from impairments less severe than blindness, such as amblyopia, strabismus, or high myopia?
Mike May, more than two decades after corrective surgery, still confuses shadows with holes in the ground, and he still has trouble determining the difference between men’s and women’s faces. He has been heard to say that he sometimes prefers using blindness skills in preference to eyesight.
Lee, now a senior adult with functioning eyesight, is still deficient in facial recognition, spatial awareness, and sensory integration, in addition to retaining all of the DVC symptoms listed above. Concentrated effort and alternate learning modalities have, however, yielded some improvement.
ACVI seems to occur at different levels of severity. Any amount of recovery would likely be analogous to that severity and the duration of the initial impairment. Concerted effort at learning compensatory skills might be the most effective approach.
Action is Needed
CVI is the leading cause of visual impairment in U.S. children,(15) and it is unavoidable. ACVI from delayed vision correction, however, can be prevented. Something as simple as earlier fitting with prescription glasses, plus improved special education services when necessary, might be enough to ward off more serious neurological problems in later childhood.
The Vision Council of America reported in 2005 that only 33 states required vision screenings for students. Since 29 of those states did not require children who fail the screening to seek recommended treatment or correction, as many as two-thirds never received follow-up exams.(16)That would include children with seriously impaired vision (uncorrected VA of 20/200 or worse) whose acuity is eventually corrected, but not until after their most formative years (i.e. age 6 or 7).
If delayed vision correction can lead to ACVI, resulting in behavioral difficulties and unusual learning modalities, an obvious solution is early-childhood diagnosis and correction. Toward that end, public and professional education is vital, and government financial assistance will be necessary to help support screening programs and assist with follow-up intervention when necessary.
Families also need to be aware of the challenges of visual functioning and sensory integration for CVI and ACVI children. Accommodation of their optimum development and their continued quality of life is vital to their well-being and to the benefit of society.
1 SeetoLearnProgram (EyecareCouncil,Inc. http://seetolearn.com)
2 Noppeney, U. The effects of visual deprivation on functional and structural organization of the human brain (Neurosci Biobehav Rev: May 13, 2007)
3 Liu Y, et al, “Whole brain functional connectivity in the early blind” (Brain: May 28, 2007)
4 Mary T. Morse, Ph.D. Autistic Spectrum Disorders and Cortical Visual Impairment: Two Worlds on Parallel Courses (AER/Denver: July 2000
6 Christine Roman-Lantzy, Ph.D., et al. CVI = Consensus, Vision, and Initiative: Mobilizing Advocacy to Improve Special Education for Children with CVI. (The American Foundation for the Blind Teleseminar: March 14, 2018)
7 Kurson,Robert. CrashingThrough (RandomHouse, NewYork: 2007)
8 Torsten N. Wiesel and David H. Hubel. Ordered Arrangement of Orientation Columns in Monkeys Lacking Visual Experience. (J. Comp. Neur 158, pp 307-318: 1974)
10 Terese Pawletko, Ph.D., Lorraine Rocissano, Ph.D. & Mary Morse, Ph.D. Autistic Spectrum Disorders and Cortical Visual Impairment: Two Worlds on Parallel Courses (AER/DENVER: July 18, 2000)
11 David B. Granet, M.D., Interview by Thomas D. Schram (HealthSCOUT, www.healthatoz.com, April 23, 2000)
12 Melvin Kaplan, O. D., Interview by Dr. Stephen M. Edelson (www.autism.org/interview/kaplan.html, September 17, 1996)
13 Sinha, P., Psychological Science (Vol 17. Issue 12. pp 1095-1100, December 2006)
14 Geoffrey K. Aguirre, et al . Canine and Human Visual Cortex Intact and Responsive Despite Early Retinal Blindness from RPE65 Mutation (PLoS Med. 2007 Jun 26; 4(6): e230)
15 Cortical Visual Impairment (published online by the American Association for Pediatric Ophthalmology and Strabismus at https://aapos.org/terms/conditions/40: rev. November 2017)
16 Making the Grade?–An analysis of state and federal children’s vision care policy (Vision Council of America, Alexandria VA: July 2005)