Optic Nerve Hypoplasia and Autism: Common Features of Spectrum Diseases

Abstract

Autism is a developmental disorder characterized by impaired social interaction, problems in verbal and nonverbal communication, and stereotyped or repetitive activities and interests. Rather than a single condition, autism is today generally regarded as consisting of a spectrum of pervasive developmental disorders that together are known as autism spectrum disorders (ASDs). Optic nerve hypoplasia (ONH) is a congenital condition characterized by underdeveloped optic nerves and neurological impairment involving endocrine dysfunction and developmental delay, with or without brain malformations that are visible by way of neuroimaging tools. Increasing in prevalence, ONH is now the leading single ocular cause of blindness in children in the developed world, affecting 10.9 per 100,000 births (Patel, McNally, Harrison, Lloyd, & Clayton, 2006; Hatton, Schwietz, Boyer, & Rychwalski, 2007). Clinical observations and recent reports indicate a high frequency of ASDs in children with ONH (Ek, Fernell, & Jacobson, 2005; Parr, Dale, Shaffer, & Salt, 2010). In children with ONH, there are additional characteristics of ASD beyond those attributable to visual impairment alone, such as echolalia and stereotypic motor movements. We argue that ONH, like ASDs, should be considered a spectrum disorder to account for the range of severity in outcomes and symptoms associated with this condition. In addition, we believe the similarities in the two conditions illustrate the possibility of a shared neurodevelopmental origin. Comparing the similarities in these conditions may lead to a greater understanding of the risk factors contributing to either condition, as well as potential clinical outcomes, as the relationship is further explored. ASD AND BLINDNESS It is not surprising that ASDs are prevalent in children with ONH when one considers that published data indicate ASDs are overrepresented in the visually impaired population, with prevalence estimates as high as 1 case of autism in every 4 visually impaired persons (Brown, Hobson, Lee, & Stevenson, 1997), compared to 1 out of 110 in the general population (Rice, 2009). The behaviors and characteristics of children with vision impairment that resemble those of children with ASDs, including echolalia, pronoun reversal, stereotypic motor movements, and delays in developing pretend play, are often attributed to the vision impairment itself (Andrews & Wyver, 2005). These behaviors may be termed blindisms, since they are explainable in the context of vision impairment. (For example, rocking or spinning may provide needed vestibular stimulation in a child with limited mobility due to lack of vision; language development and social interactions may be impaired in congenitally blind children due to their lack of concrete experiences and visual models.) The similarity of these blindisms to autistic-like behaviors, coupled with the absence of autism diagnostic measures designed for use with people who are blind or visually impaired, complicates the diagnosis of ASDs in children who are visually impaired. Thus, the debate concerning whether true autism is prevalent in children who are visually impaired remains unresolved. ASDs AND ONH Most reports of ASDs in children with vision impairment (ASDVI) are limited to children who have severe congenital blindness regardless of any cause (Brown, Hobson, Lee, & Stevenson 1977; Ek, Fernell, Jacobson, & Gillberg, 1998). There are a few reports focused specifically on children with ONH. In a group of 13 Swedish children with ONH and blindness, 6 had ASDs and 3 had autistic-like conditions. The remaining 4 children did not fall on the autism spectrum (Ek, Fernell, & Jacobson, 2005). Parr and colleagues reported in a sample of 83 children with ONH and severe vision impairment (with acuities of worse than 6/30), 31 (37%) had social, communicative, and repetitive or restricted behavioral difficulties. …