Purpose

To investigate the relationship between myopia progression and axial length (AL) elongation in orthokeratology (ortho-k) patients.

Methods

This study investigated 184 patients (baseline age 9.0 ± 1.6 years), who underwent overnight ortho-k treatment for 12 to 72 months, and stopped lens wear for 1 to 2 months. Refractive sphere and cylinder after cycloplegia, corneal curvatures along both meridians, and AL were compared before the commencement and after discontinuation of ortho-k treatment. The effects of AL change, baseline AL, corneal curvature change, baseline age, and duration of ortho-k treatment on the change in spherical equivalent refractive error (SER) were analysed.

Results

Myopia significantly progressed and AL increased following 32.8 ± 13.0 months of ortho-k lens wear and 1 to 2 months washout period, as compared to baseline (all P < 0.001). Corneal curvature along the flat meridian (FK) became significantly flatter (P < 0.001) and corneal curvature along the steep meridian (SK) became steeper (P = 0.036). In the first stepwise multiple linear regression model (R² = 0.696), the change in SER over time (ΔSER) is significantly correlated to the change in AL (ΔAL, P < 0.001), baseline AL (P < 0.001), baseline age (P = 0.028), change in SK (P = 0.002), and the duration of ortho-k lens treatment before discontinuation (P = 0.010). In a more simplified model (R² = 0.628), the regression equation using ΔAL to predict ΔSER is: ΔSER = -0.094–1.608*ΔAL.

Conclusions

The change in SER was significantly correlated to the change in AL, change in SK, baseline AL, baseline age, and the duration of treatment among children undergoing ortho-k therapy. The ratio of axial elongation to myopia progression was approximately 1:1.6 between the ages of 6 to 14 years. A simplified equation was derived for clinical use to estimate myopia progression from repeated AL measurement in ortho-k patients.

中文翻译：

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角膜塑形镜配戴儿童近视加深与眼轴伸长的关系

目的

探讨角膜塑形术 ( ortho -k) 患者的近视进展与眼轴 (AL) 伸长率之间的关系。

方法

本研究调查了 184 名患者（基线年龄 9.0 ± 1.6 岁），他们接受了12 至 72 个月的过夜矫正治疗，并停戴了 1 至 2 个月的镜片。在ortho -k 治疗开始前和停止后比较睫状肌麻痹后的屈光球体和圆柱体、沿两条子午线的角膜曲率和 AL 。分析了AL 变化、基线 AL、角膜曲率变化、基线年龄和ortho -k 治疗持续时间对球面等效屈光不正 (SER) 变化的影响。

结果

与基线相比，在佩戴ortho -k 镜片32.8 ± 13.0 个月和 1 至 2 个月的洗脱期后，近视显着恶化并且 AL 增加（所有 P < 0.001）。沿平坦子午线 (FK) 的角膜曲率变得更平坦 (P < 0.001)，而沿陡峭子午线 (SK) 的角膜曲率变得更陡峭 (P = 0.036)。在第一个逐步多元线性回归模型 (R ²  = 0.696) 中，SER 随时间的变化 (ΔSER) 与 AL (ΔAL, P < 0.001)、基线 AL (P < 0.001)、基线年龄的变化显着相关(P = 0.028)、SK 的变化 (P = 0.002) 以及停用前矫正-k 镜片治疗的持续时间 (P = 0.010)。在更简化的模型中 (R ² = 0.628)，用ΔAL预测ΔSER的回归方程为：ΔSER = -0.094–1.608*ΔAL。

结论

SER 的变化与接受ortho -k 治疗的儿童的 AL 变化、SK 变化、基线 AL、基线年龄和治疗持续时间显着相关。在 6 至 14 岁之间，眼轴伸长与近视进展的比率约为 1:1.6。推导了一个简化的方程式，供临床使用，以估计ortho -k 患者重复 AL 测量的近视进展。