Myopic anisometropia: ocular characteristics and aetiological considerations

Abstract

Anisometropia represents a unique example of ocular development, where the two eyes of an individual, with an identical genetic background and seemingly subject to identical environmental influences, can grow asymmetrically to produce significantly different refractive errors. This review provides an overview of the research examining myopic anisometropia, the ocular characteristics underlying the condition and the potential aetiological factors involved. Various mechanical factors are discussed, including corneal structure, intraocular pressure and forces generated during near work that may contribute to development of anisomyopia. Potential visually guided mechanisms of unequal ocular growth are also explored, including the influence of astigmatism, accommodation, higher‐order aberrations and the choroidal response to altered visual experience. The association between binocular vision, ocular dominance and asymmetric refraction is also considered, along with a review of the genetic contribution to the aetiology of myopic anisometropia. Despite a significant amount of research into the biomechanical, structural and optical characteristics of anisometropic eyes, there is still no unifying theory, which adequately explains how two eyes within the same visual system grow to different endpoints.

Key words:

• anisometropia
• myopia
• ocular biometrics
• ocular growth
• refractive error

Acknowledgements

The authors thank Dr Fan Yi and Mr Stephen Witt for assistance in the translation of foreign texts.

SUPPORTING INFORMATION

Additional Supporting Information may be found in the online version of this article at the publisher’s website:

Table-S1. Summary of biometric studies of myopic anisometropia

Table-S2. Summary of cross sectional studies of IOP in anisometropic cohorts

Table-S3. Summary of cross‐sectional studies of corneal power (or radius of curvature) in anisometropia

Table-S4. Summary of studies of accommodation in myopic anisometropia

Table-S5. Summary of studies of higher‐order aberrations in anisometropia

Table-S6. Summary of studies of ocular sighting dominance and refractive error