Research progress on the influence of decentered orthokeratology treatment zones on myopia control

Orthokeratology (OK) lens is an effective method for myopia control in children and adolescents, and decentration of the treatment zone is a common clinical phenomenon. Currently, the assessment of treatment zone decentration following OK lens wear relies primarily on tangential curvature data derived from corneal topography. Corneal morphological asymmetry, including corneal astigmatism, the mean elevation difference at the 8 mm chord, and the corneal asymmetry vector, is identified as the main contributor to decentration. In clinical practice, inferotemporal direction is a common type of decentration. Regarding the impact of decentration on myopia control, findings are divergent. Some studies suggest a negative correlation between the magnitude of decentration and axial elongation. Proposed mechanisms include alterations in the characteristics of the central optical zone, increasing the value of relative corneal refractive power and altering its spatial distribution, inducing positive spherical aberration to reduce accommodative lag, enhancing the asymmetry and blur intensity of peripheral retinal defocus signals, and influencing the activation state of S-cones. These multiple optical and neurobiological pathways may affect myopia progression. Conversely, other research indicates no association, or even a positive correlation, between decentration and axial elongation. Although severe decentration may increase the risk of corneal epithelial staining, evidence regarding its overall safety profile remains inconsistent. Future research should employ long-term, multi-center studies combined with artificial intelligence-assisted standardized assessment of the treatment zone to define the safe threshold of decentration and explore its potential value for active modulation, thereby optimizing myopia control strategies. This article provides a systematic review focusing on the evaluation methods, influencing factors, myopia control efficacy, potential mechanisms, and complications associated with decentered OK treatment zones.