Sanislo S, Wicker D, Green D G
Department of Ophthalmology, W.K. Kellogg Eye Center, University of Michigan, Ann Arbor 48109.
CLAO J. 1992 Jul;18(3):161-4.
We examined the contrast sensitivity function of presbyopic subjects wearing the Hydron Echelon diffractive bifocal contact lens. Contrast sensitivity with the Echelon lens was compared to contrast sensitivity with bifocal spectacle correction. Each eye was tested for near and distance vision with the Echelon contact lens and with spectacle correction. Most subjects achieved a visual acuity of 20/20 with the Echelon lens; however, on average, contrast sensitivity was found to be significantly decreased with the contact lens as compared to spectacles for both distance and near vision. The largest decrease in contrast sensitivity was seen for mid-range spatial frequencies (4 to 16 cycles/degree). Although most subjects experienced a significant decrease in contrast sensitivity, two experienced only small decreases with the Echelon lens. Only one subject who met entry criteria reported that vision was as good with the Echelon lens as with spectacles. The decreased contrast sensitivity may result from contact lens decentration as well as inherent optical characteristics of the Echelon lens.
我们检测了佩戴Hydron Echelon衍射双焦点隐形眼镜的老花眼受试者的对比敏感度函数。将佩戴Echelon镜片时的对比敏感度与双焦点眼镜矫正时的对比敏感度进行比较。分别用Echelon隐形眼镜和眼镜矫正对每只眼睛的近视力和远视力进行测试。大多数受试者使用Echelon镜片时视力达到20/20；然而，平均而言，与眼镜相比，隐形眼镜在远视力和近视力方面的对比敏感度均显著降低。在中等空间频率（4至16周/度）下，对比敏感度下降最为明显。虽然大多数受试者的对比敏感度显著下降，但有两名受试者使用Echelon镜片时对比敏感度仅略有下降。只有一名符合入选标准的受试者报告称，使用Echelon镜片时的视力与使用眼镜时一样好。对比敏感度下降可能是由于隐形眼镜偏心以及Echelon镜片固有的光学特性所致。
