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

Abstract

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.