Amblyopia, Strabismus More Common in Children with Autism Spectrum Disorder

A recent population-based American Journal of Ophthalmology study suggests an increased risk of ophthalmologic diagnoses in children with autism spectrum disorder (ASD). 

Core diagnostic features of ASD include sensory abnormalities, and several aspects of higher-order visual processing are impacted. Visual attention is recognized as abnormal in individuals with an ASD diagnosis, and it has been suggested as a reason for early screening and treatment. However, the association between ASD and ophthalmologic disorders, such as amblyopia and strabismus, is less understood. 

To better understand the connection, investigators used claims from a longitudinal real-world data asset, OptumLabs Data Warehouse, with de-identified administrative claims and electronic health records data on enrollees and patients. The data was representative of a mixture of ages, ethnicities and geographical regions across the United States to determine the rates of ophthalmologic disorders in children with ASD.

The authors write, “Because we used records from the International Classification of Disease-9 (ICD-9) era, when there was no code for ‘autism spectrum disorder,’ we evaluated records for children diagnosed with pervasive developmental disorders (PDD), as well as the subset of children with autistic disorder (AD). We assessed the rates of the top 5 ophthalmologic disorders (excluding refractive error) reported in prior single-center retrospective studies of children with ASD: amblyopia, strabismus, nystagmus, optic neuropathy, and retinopathy of prematurity (ROP).”

Patients were included in this analysis if they were 18 years old or younger at the time of first claim during the specified date range: 2007 to 2013. Children were categorized into 3 groups: typically developing (TD) controls (10,815,576 participants); pervasive developmental disorder (PDD) (100,854 participants); and autistic disorder (AD)(61,167 participants) based on ICD-9 codes (PDD: 299.XX, AD: 299.0X). Children who did not have either PDD or AD were TD controls. All children with a diagnosis of AD were included in the PDD group, but some children with PDD were not diagnosed with AD, for example Asperger syndrome. 

For each group, the authors calculated the rates of the 5 ophthalmologic diagnoses of interest, based on prior studies suggesting increased risk in children with ASD:

• strabismus 
• amblyopia 
• nystagmus
• optic neuropathy
• retinopathy of prematurity (ROP) 

The authors report that 12.5% of children with PDD and 13.5% of children with AD were diagnosed with any of 5 ophthalmologic disorders (identified in previous studies as the most common in children with ASD), compared with 3.5% of control children. Amblyopia was seen in 3.6% of children with PDD and 3.8% of those with AD, compared with 1.2% of TD controls while strabismus was diagnosed in 9.6% of children with PDD and 10.4% of children with AD, compared with 2.4% of TD controls. Optic neuropathy occurred in 1.0% of children with PDD and 1.1% of children with AD, compared with 0.3% of TD controls and ROP, which was only present in 0.2% of TD controls, was diagnosed in 0.4% of children with PDD and 0.5% of children with AD.

“The association between ophthalmologic disorders and ASD raises the question of whether visual and oculomotor abnormalities, in some patients, contribute to autism symptomatology. As sensory sensitivities are now recognized as a core feature of autism, there is debate as to whether sensory abnormalities are primary or secondary to abnormal social behaviors and attention,” the study says. “This may explain why children with visual impairment exhibit ‘blindisms’ that mimic autistic behavior — for example, repetitive eye poking or body rocking. Oculomotor abnormalities, such as decreased saccadic accuracy, have also been demonstrated in children with ASD, and could relate to ophthalmologic diagnoses such as amblyopia and nystagmus.”

The researchers also note that the association of ophthalmologic disorders with ASD suggests that ophthalmic pathology could represent a new endophenotype of ASD that assists in parsing the heterogeneity of this disorder. Endophenotypes are quantitative behavioral or biological features with a genetic basis; in heterogeneous neuropsychiatric disorders such as ASD, endophenotypes may assist in prognostication and direct targeted therapy.

Reference
Chang MY, Doppee D, Yu F, Perez C, Coleman AL, Pineles SL. Prevalence of ophthalmologic diagnoses in children with autism spectrum disorder using the Optum dataset: a population-based study. Am J Ophthalmol. Published online September 4, 2020. doi: 10.1016/j.ajo.2020.08.048.