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Association of Axial Length and Refraction with Near Horizontal Heterophoria in Chinese Children: An Observational
Xiaoqin Chen1,2,3,4, Yanglin Jiang1,2,3,4, Qian Fan1,2,3
1Tianjin Eye Hospital and Nankai University Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin, China.
Insights
Exophoria is the most common near heterophoria in children. More severe near heterophoria correlates with increased myopia and longer axial length (AL), suggesting a role in visual development.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Public Health
Background:
- Near heterophoria is a common condition affecting binocular vision in children.
- Understanding its association with refractive error and axial length is crucial for early intervention.
Purpose of the Study:
- To evaluate the association between near heterophoria and refractive error (spherical equivalent) and axial length (AL) in Chinese school children.
Main Methods:
- A cross-sectional study of 11,013 Chinese primary school students (grades 1-6).
- Near heterophoria measured using Maddox rod and prism test; refraction and AL measured.
- Generalized additive models used to analyze associations, adjusted for age.
Main Results:
- Exophoria was the most prevalent type of near heterophoria (64.96%), increasing with grade level.
- Children with orthophoria had significantly lower myopia and shorter AL compared to those with exophoria or esophoria (P < 0.001).
- Near heterophoria showed a significant correlation with refraction and AL, independent of age.
Conclusions:
- Exophoria is the predominant form of near heterophoria in this pediatric population.
- Increased severity of near heterophoria (exophoria or esophoria) is linked to higher myopia and longer axial length.
- Further longitudinal research is warranted to elucidate the role of near heterophoria in visual development.
Purpose:
To evaluate the association of near heterophoria with refraction and axial length (AL) in Chinese school children.
Methods:
This school-based cross-sectional study included 15,081 Chinese primary school children (grades 1-6) examined during 2017. Near heterophoria was measured at 33 cm using the Maddox rod and prism test. Noncycloplegic refraction and AL were also measured. A generalized additive model with a Gaussian link was used to determine the association of near heterophoria with refraction and AL. Analyses were adjusted for age to account for differences in the age distribution of the sample.
Results:
Overall, data were analyzed for 11,013 students ranging in age from 6 to 13 years. The most common type of near heterophoria was exophoria (64.96%), the proportion and value of which increased according to grade. Exophoria accounted for 62.53% (2,328/3,723), 65.03% (2,501/3,846), and 67.51% (2,325/3,444) of near heterophoria cases for grades 1-2, grades 3-4, and grades 5-6, respectively. Prism diopter (PD) values for near heterophoria in these grades were -6.30 ± 3.69, -6.81 ± 4.01, and -8.32 ± 5.12 PD, respectively. The average spherical equivalent (SE) in children with orthophoria was 0.23 D and 0.25 D lower than those in children with exophoria and esophoria, respectively (P < 0.001). The mean AL in children with orthophoria was 0.11 mm shorter than that in children with either exophoria or esophoria (P < 0.001). Near heterophoria exhibited a significant correlation with refraction and AL, irrespective of age.
Conclusions:
Exophoria represents the most common type of near heterophoria in children. Children with more severe near heterophoria, whether exophoria or esophoria, exhibited a higher degree of myopia and longer AL than those with relatively less severe near heterophoria. These results highlight the need for further, long-term investigation regarding the role of near heterophoria in visual development.
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