Laterality of Amblyopia in the United States: A Preliminary Analysis from the 2017 IRIS Registry

Abstract

Purpose : Laterality differences in amblyopia have been observed in several studies, though typically with small sample sizes. Here, we utilized a large population dataset to determine the prevalence of amblyopia in the left versus right eye in the United States.

Methods : Electronic medical records of patients diagnosed with amblyopia in at least one eye were extracted from the 2017 Intelligent Research in Sight (IRIS) Registry database curated by the American Academy of Ophthalmology. Categories of amblyopia were defined by the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) code. Four types of amblyopia were documented: unspecified amblyopia (ICD-10 code H53.00), deprivation amblyopia (H53.01), refractive amblyopia (H53.02), and strabismic amblyopia (H53.03). For each type of amblyopia, the prevalence of unilateral or bilateral disease was calculated. Subsequently, among those with unilateral amblyopia, the prevalence of disease in the left or right eye was analyzed. The binomial test was used to assess statistical significance.

Results : A total of 112,800 patients with amblyopia were extracted from the 2017 IRIS Registry. Of these patients, 51,484, 3,421, 37,918, and 19,977 had unspecified, deprivation, refractive, and strabismic amblyopia, respectively. The mean and standard deviations (SD) of age and gender ratios can be found in Table 1. All four types of amblyopia occurred significantly more commonly in one eye than in both eyes (all P values < 0.001), with strabismic amblyopia having the highest ratio of unilateral diagnosis (89.5%; Figure 1A). Among those with unilateral amblyopia, the left eye was consistently more affected across all types of amblyopia (Figure 1B). Specifically, the left eye accounted for 55.4% (unspecified), 54.2% (deprivation), 55.2% (refractive), and 55.1% (strabismic) of unilateral amblyopia, respectively (all P values < 0.001).

Conclusions : For all four types of amblyopia defined by the ICD-10 code, unilateral amblyopia was significantly more prevalent than bilateral amblyopia. In patients with unilateral amblyopia, the prevalence was approximately 10% higher in the left eye than the right eye. These results are consistent with trends reported in the previous literature, confirming the findings using the much larger IRIS Registry.

This is a 2020 ARVO Annual Meeting abstract.

 

Table 1.

 

Figure 1.