The Ocular Surface Institute, University of Houston College of Optometry, Houston, USA.
Ophthalmic Physiol Opt. 2021 Mar;41(2):393-400. doi: 10.1111/opo.12770. Epub 2020 Dec 8.
Centre-distance multifocal contact lenses (MFCLs) for myopia control are thought to slow myopia progression by providing both clear foveal vision and myopic defocus. Characterising the power profile of lenses is important to understanding their possible effects on retinal defocus when worn. The power profiles of three commercially available MFCLs were determined.
Three centre-distance MFCL designs were studied: Biofinity Multifocal D +2.50 add (comfilcon A), Proclear Multifocal D +2.50 add (omafilcon A), and NaturalVue Multifocal (etafilcon A). Two lenses each in power from -1.00D to -6.00D in 1D steps were stored in ISO 18369-3:2017 standard phosphate buffered saline for 24 h. Optical power profiles were measured in a wet cell with the SHSOphthalmic profiler accounting for centre thickness and manufacturer-reported material refractive index. Sagittal power maps from the SHSOphthalmic were exported, and custom MATLAB code was used to generate power profiles by averaging along the vertical and horizontal meridians. One-way anova with Tukey's HSD post-hoc t-tests were used to analyse maximum add power by lens design.
Plus power increased out from the lens centre for all three MFCLs. Power profiles of Biofinity D and Proclear D MFCLs show three distinct areas within the optic zone; the distance zone (from lens centre to about 1.6 mm radius), intermediate zone (about 1.6 mm radius to 2.1 mm) and near zone (about 2 mm radius to 4 mm). For NaturalVue MFCLs, plus power starts increasing almost immediately from the lens centre, reaching maximum measured mean plus power at a radius of 2.7 mm. From 2.7 mm to 3.0 mm, there was a decrease in plus power, which was then generally maintained out to the optic zone edge. Across all lens powers, maximum add power was highest with the NaturalVue MFCL (+3.32 ± 0.44D), then Proclear D (+1.84 ± 0.28D) and Biofinity D (+1.47 ± 0.34D) MFCLs (all p < 0.04). Add power peaked at different locations for different lens powers and designs.
Power profiles of MFCLs vary based on lens design and power. These power profiles are consistent with reported myopic and hyperopic changes in peripheral refraction with MFCLs and provide some explanation for reported differences in peripheral refraction with these MFCLs. Further work is needed to determine whether these power profile differences influence myopia progression.
中心距多焦点接触镜（MFCL）被认为通过提供清晰的中央凹视力和近视离焦来减缓近视进展。了解镜片的屈光力分布对理解佩戴时对视网膜离焦的可能影响很重要。本研究旨在确定三种市售的中心距 MFCL 的屈光力分布。
研究了三种中心距 MFCL 设计：Biofinity Multifocal D +2.50 add（comfilcon A）、Proclear Multifocal D +2.50 add（omafilcon A）和 NaturalVue Multifocal（etafilcon A）。将两种各从-1.00D 到-6.00D 以 1D 步长的镜片存储在 ISO 18369-3：2017 标准磷酸盐缓冲盐中 24 小时。使用 SHSOphthalmic 轮廓仪在湿室中测量光学屈光力，该仪器考虑了中心厚度和制造商报告的材料折射率。从 SHSOphthalmic 导出矢状屈光力图，并使用自定义 MATLAB 代码通过沿垂直和水平子午线平均生成屈光力分布。使用单因素方差分析和 Tukey 的 HSD 事后 t 检验分析不同镜片设计的最大附加屈光力。
对于所有三种 MFCL，正屈光力从镜片中心向外增加。Biofinity D 和 Proclear D MFCL 的屈光力分布在光学区显示出三个不同的区域；离焦区（从镜片中心到约 1.6mm 半径）、中间区（约 1.6mm 半径到 2.1mm）和近区（约 2mm 半径到 4mm）。对于 NaturalVue MFCL，正屈光力几乎从镜片中心立即开始增加，在半径为 2.7mm 时达到最大测量平均正屈光力。在 2.7mm 到 3.0mm 之间，正屈光力下降，然后在光学区边缘基本保持不变。在所有镜片屈光力下，NaturalVue MFCL 的最大附加屈光力最高（+3.32±0.44D），其次是 Proclear D（+1.84±0.28D）和 Biofinity D（+1.47±0.34D）MFCL（均 p<0.04）。不同的镜片设计和屈光力在不同位置达到最大附加屈光力。
MFCL 的屈光力分布取决于镜片设计和屈光力。这些屈光力分布与报告的 MFCL 周边近视和远视变化一致，并为这些 MFCL 报告的周边折射差异提供了一些解释。需要进一步研究以确定这些屈光力分布差异是否影响近视进展。
