Corneal elevation asymmetry vector: Viable predictor of severe one-year-averaged orthokeratology lens decentration

Background

To assess the predictive value of pretreatment corneal elevation asymmetry vector (CEAV) for severe orthokeratology (Ortho-k) lens decentration (LD) in Chinese myopic adolescents.

Methods

A retrospective analysis of 247 myopic participants over one year employed a novel MATLAB algorithm to calculate CEAV and precise LD vector. Subjects were categorized into mild (<1 mm) and severe (≥1 mm) yearly averaged LD (YALD) groups. Logistic regression and ROC analysis evaluated the relationship between corneal parameters and severe YALD.

Results

LD reached stability within the first month, with severe YALD compromising visual quality and corneal health. Notably, univariate linear regression revealed a paradoxical correlation between axial length elongation (ALE) and YALD: ALE negatively correlated with YALD in the mild group (standardised β = -0.546, P < 0.05), contrasting with a positive correlation in the severe group (standardised β = 0.599, P < 0.05). Horizontal CEAV (standardised β =  − 0.237, < 0.05) and curvature differences between nasal and temporal quadrants at 8 mm (K_TN) (standardised β = 0.227, P < 0.01) significantly correlated with horizontal YALD, while vertical CEAV vector associated with vertical YALD (standardised β =  − 0.237, < 0.05). Multivariate analysis identified CEAV as an independent predictor of severe YALD (OR = 3.145, 95 % CI: 1.334 ∼ 4.607, P < 0.01). Other risk factors included larger horizontal visible iris diameter (HVID) (OR = 2.430, 95 % CI:0.6136 ∼ 10.07, P < 0.05), corneal astigmatism (CA) (OR = 1.506, 95 % CI: 1.017 ∼ 2.244, P < 0.05), and K_TN (OR = 1.864, 95 % CI: 0.934 ∼ 3.864, P < 0.05). CEAV magnitude alone predicted severe YALD with AUC = 0.698 (95 %CI: 0.615–0.783, P < 0.001), improving to AUC = 0.732 (95 % CI: 0.660–0.805, P < 0.001) when combined with other risk factors.

Conclusions

Pretreatment CEAV may emerge as a viable predictor of severe Ortho-k YALD, warranting its consideration in further tailored lens fitting to improve outcomes.