Refractive Profile of Surgical Patients with Intermittent Exotropia: A Large-Sample Cross-Sectional Study in Southern China

Abstract

Purpose

To describe the refractive profile of surgical patients with intermittent exotropia (IXT) residing in southern China.

Methods

Medical records of patients who received strabismus surgery between June 2014 and August 2020 were retrospectively reviewed. Clinical data, including age, sex, refractive errors, preoperative angle of deviation, types of exotropia, accommodative convergence to accommodation ratio (AC/A ratio) and stereopsis, were investigated.

Results

A total of 2250 patients were included, and 93.6% of patients were younger than 30 years of age. The mean angle of exodeviation was 37.0 ± 14.7 prism degree (PD) and 37.5 ± 15.8 PD at distance and near, respectively. Mean spherical equivalent refraction (SER) values were -0.7 ± 2.4 D and −0.8 ± 2.5 D in the dominant eye and nondominant eye, respectively. Significant differences in SER were observed between the dominant eye and nondominant eye among children at 6 years old or younger. The percentage of myopia increased from 11.0% in children (≤6 years old) to 77.9% in teenagers (13-18 years of age). Significant positive associations between the magnitude of exodeviation and the magnitude of myopia were observed (p < 0.0001). Patients with convergence insufficiency type IXT (p < 0.0001) or AC/A < 2 (p < 0.05) showed a greater magnitude of myopia. The mild hyperopia group included a larger proportion of subjects showing a certain degree of stereopsis (p < 0.05).

Conclusions

Myopia was present in more than half of our patients (51.2%), which is much higher than the percentage in the general population of southern China. Patients with convergence insufficiency, an AC/A ratio < 2, or a larger angle of deviation tended to have a greater magnitude of myopia.

Keywords:

• Myopia
• intermittent exotropia
• AC/A

Acknowledgements

We are indebted to Dr. Zongyi Zhan and Dr. Zhouyue Li for their helpful criticism of this manuscript.

Ethics statement

This study protocol was reviewed and approved by the ethics committee of the Zhongshan Ophthalmic Center, Sun Yat-sen University, approval number NO.2022KYPJ109. This study was performed in compliance with the Declaration of Helsinki. All procedures performed in studies involving human participants were in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Authors’ contributions

YW, TS, JCSY and JHY had full access to the all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: YW, TS, JCSY and JHY. Acquisition, analysis, interpretation of data: YW. Drafting of the manuscript: YW.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

This study was supported by Guangdong Basic and Applied Basic Research Foundation [2021A1515110490] and Medical Scientific Research Foundation of Guangdong Province of China [A2022348] to Yun Wen.