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Inter-eye Differences in Ocular Biometric Parameters of Concomitant Exotropia
Weifen Gong1, Haoyu Chen1, Fan Yang1
1Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong, Shantou, China.
Frontiers in Medicine
|January 21, 2022
Summary
Patients with concomitant exotropia exhibit greater inter-eye differences in ocular biometric parameters, including axial length and anterior chamber depth. Early advice for children may help prevent or delay this condition.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Pediatric Optometry
Background:
- Exotropia is a common childhood strabismus characterized by outward deviation of the eyes.
- Accurate ocular biometric measurements are crucial for understanding refractive development and managing strabismus.
- Swept-source optical coherence tomography (SS-OCT) offers high-resolution, non-contact measurement of ocular parameters.
Purpose of the Study:
- To compare ocular biometric parameters between patients with constant and intermittent exotropia and healthy controls.
- To evaluate the utility of the OA-2000 SS-OCT biometer in assessing these differences.
- To identify potential biometric markers associated with exotropia development.
Main Methods:
- A cross-sectional case-control study involving 79 exotropia patients (55 constant, 24 intermittent) and 77 orthotropic controls, aged 4-18 years.
- Non-contact ocular biometry using the OA-2000 SS-OCT biometer under standardized conditions.
- Statistical analysis included intraclass correlation coefficient (ICC), Bland-Altman plots, and independent t-tests to compare inter-eye differences (AnisoSE, AnisoPD, AnisoACD, AnisoLT, AnisoAL).
Main Results:
- Patients with concomitant exotropia demonstrated significantly larger inter-eye differences in spherical equivalent (AnisoSE), axial length (AnisoAL), anterior chamber depth (AnisoACD), lens thickness (AnisoLT), and pupil diameter (AnisoPD) compared to controls.
- Binocular correlation (ICC) for ocular parameters was excellent in controls (0.943-0.987) and good in exotropia patients (0.767-0.955).
- Bland-Altman analysis revealed wider agreement ranges for all measured parameters in exotropia patients than in controls.
Conclusions:
- Concomitant exotropia is associated with greater inter-eye asymmetry in key ocular biometric parameters.
- The OA-2000 SS-OCT biometer effectively quantifies these differences.
- Early intervention and advice for at-risk children may be beneficial in preventing or delaying the onset of concomitant exotropia.
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