Xie Pei-Ying, Chi Hui, Yang Li-Na
Bei Yi Optometry & Ophthalmology Center, Beijing 100028, China.
Zhonghua Yan Ke Za Zhi. 2011 Jan;47(1):50-3.
To evaluate the oxygen transmissibility of new material Piggyback lens combined with silicone hydrogel lens and higher Dk RGPCL. To investigate the improving of visual acuity, ocular shape and comfortable, also orthokeratology results and safety of this new system for keratoconus correction.
Calculating the oxygen transmission (Dk/t) of the new Piggyback system involves Ohm's Law. Compare the changes of ocular surface curves and astigmatism with or without Si-SCL fitting, RGPCL vision and Piggyback lens vision. Investigate the comfortable improving and ocular complications, and changes of corneal shape after fitted with Piggyback lens by using corneal topography.
Selected silicone hydrogel lens was pure vision (B&L PV, 36% water, Dk/t 110) lens, RGPCL material was Menicon Z, Dk/t 95.9 and Boston XO, Dk/t 58.8. It was calculated to 44.4 Dk/t and 34.4 Dk/t with these two combinations. Twenty two moderate and severe keratoconus patients (28 eyes) fitted with the Piggyback lens successfully. Corneal K reading and astigmatism decreased significantly after wore the Si-SCL. Compared with RGPCL vision(4.82 ± 0.11), Piggyback lens vision (4.93 ± 0.08) was significant increased (t = -10.395, P < 0.01) 90% cases improved comfort vs prior RGPCL wear alone. Only few cases appeared slight conjunctival hyperemia and corneal staining. Corneal topography showed corneal flatter, spherical and regular reshaping results after 6 months wore the Piggyback lens.
By fitting Piggyback systems using new Si-SCL and higher Dk RGPCL materials may help problematic keratoconic patients improve visual acuity, comfort and safety, increase wearing time and orthokeratology results further.
评估新型背负式镜片联合硅水凝胶镜片及高透氧性硬性透气性角膜接触镜（RGPCL）的透氧性。研究该新系统对圆锥角膜矫正的视力改善、眼部形态及舒适度的影响，以及角膜塑形效果和安全性。
运用欧姆定律计算新型背负式系统的氧气透过率（Dk/t）。比较佩戴或不佩戴硅水凝胶软性角膜接触镜（Si-SCL）时眼表曲线和散光的变化、RGPCL视力与背负式镜片视力。通过角膜地形图研究佩戴背负式镜片后舒适度的改善情况、眼部并发症以及角膜形态的变化。
选用的硅水凝胶镜片为纯视（B&L PV，含水量36%，Dk/t 110）镜片，RGPCL材料为目立康Z，Dk/t 95.9以及波士顿XO，Dk/t 58.8。这两种组合计算得出的Dk/t分别为44.4 Dk/t和34.4 Dk/t。22例中重度圆锥角膜患者（28只眼）成功佩戴了背负式镜片。佩戴Si-SCL后角膜曲率读数和散光显著降低。与RGPCL视力（4.82±0.11）相比，背负式镜片视力（4.93±0.08）显著提高（t = -10.395，P < 0.01），90%的病例舒适度相较于单独佩戴之前的RGPCL有所改善。仅少数病例出现轻微结膜充血和角膜染色。角膜地形图显示佩戴背负式镜片6个月后角膜变平、呈球形且塑形结果规则。
通过使用新型Si-SCL和高透氧性RGPCL材料的背负式系统，可能有助于圆锥角膜问题患者提高视力、舒适度和安全性，进一步延长佩戴时间并改善角膜塑形效果。
