Purpose

To study the light distortion effects of soft multifocal contact lenses and the influence of different pupil size and shape.

Methods

A total of 14 eyes of 7 healthy contact lens users (mean age 28.6 ± 8.5 years) were recruited. The “Light Disturbance Analyser” device was employed for light characterization. The selected lenses were the monthly disposable “Biofinity multifocal” (CooperVision, CA, USA), both centre-distance and centre-near designs (addition power +2.50 D). Two circular pupils of 3 mm and 5 mm of diameter, and an elliptical shape (3 horizontal and 5 vertical mm) were used. Metrics such as the light distortion index (LDI), best-fit circle radius and its irregularity were analysed, among others.

Results

The LDI was generally higher with multifocal lenses, varying from 3.7 ± 0.3 % of the single vision lens to 6.1 ± 3.3 % of the multifocal centre-distance design and the 5-mm pupil. Larger pupils gave higher LDI values, changing from 4.5 ± 2.0 % (3 mm) to 6.1 ± 3.3 % (5 mm) with the centre-distance design. The elliptical pupil produced the largest discrepancy in the distortion size between the vertical and horizontal directions. The centre-distance and centre-near designs behaved similarly in terms of light distortion.

Conclusions

The multifocal contact lenses of the study increased light distortion effects under low light conditions, especially with larger pupils. The shape of the distortion pattern is associated with the shape of the pupil. It seems that not all, but a big percentage of light distortion would be produced by the presence of the out-of-focus images given by a multifocal lens.

中文翻译：

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不同瞳孔大小和形状的软多焦点隐形眼镜的光畸变。

目的

研究软多焦点隐形眼镜的光畸变效应以及不同瞳孔大小和形状的影响。

方法

总共招募了7名健康隐形眼镜使用者（平均年龄28.6±8.5岁）的14只眼睛。使用“光干扰分析仪”设备进行光表征。选择的镜片是每月一次使用的“ Biofinity多焦点”（美国加利福尼亚州库珀视觉），均采用中距设计和近中设计（附加光焦度+2.50 D）。使用两个直径为3 mm和5 mm的椭圆形椭圆形（水平3个，垂直5个）。除其他外，还分析了诸如光畸变指数（LDI），最佳拟合圆半径及其不规则性之类的指标。

结果

多焦点镜片的LDI通常较高，从单视镜片的3.7±0.3％到多焦点中心距设计和5毫米瞳孔的6.1±3.3％不等。较大的瞳孔的LDI值较高，中心距设计从4.5±2.0％（3 mm）变为6.1±3.3％（5 mm）。椭圆形光瞳在垂直和水平方向之间的变形大小上产生最大的差异。中心距离和中心附近的设计在光失真方面表现相似。

结论

该研究的多焦点隐形眼镜在弱光条件下，特别是对于较大的瞳孔，增加了光畸变的影响。畸变图案的形状与瞳孔的形状相关联。似乎并非所有，而是由多焦点镜头给出的散焦图像的存在会产生很大比例的光失真。