Ren D H, Petroll W M, Jester J V, Ho-Fan J, Cavanagh H D
Department of Ophthalmology, University of Texas Southwestern Medical Center at Dallas, 75235-9057, USA.
CLAO J. 1999 Apr;25(2):80-100.
We designed a 3-year, prospective, randomized, masked clinical trial to evaluate the relationship of contact lens oxygen transmissibility and bacterial adherence to exfoliated surface epithelial cells in human overnight and extended lens wearers in a single center; corneal cell desquamation rate, surface epithelial cell size, and tear lactate dehydrogenase (LDH) levels were also determined concurrently.
One hundred nine human volunteers were successfully fit with test lenses prospectively and completed this study. Seven soft and three rigid gas permeable (RGP) lenses with stratified oxygen transmissibility were evaluated. After one week adaptation to daily wear, patients continually wore test lenses bilaterally for three months on a six nights wear, one night off basis. Before and after 24 hour, 1 month, and three months extended contact lens wear, exfoliated surface epithelial cells were collected using a modified corneal irrigation chamber. Bacterial binding was determined by measuring Pseudomonas aeruginosa (PA) adherence to exfoliated corneal epithelial cells. The number of exfoliated cells with adherent bacteria were counted using fluorescence microscopy. The effects of contact lens wear on the corneal surface were further assessed by alterations in tear LDH, and by surface epithelial cell size and epithelial thickness using in vivo tandem scanning confocal microscopy (TSCM). Baseline values of outcome measures served as controls for individual patients; a concurrent group of controls were also followed to monitor seasonal or possible individual fluctuations.
Quantitative evidence demonstrated that lens physical oxygen transmissibility properties and not lens type significantly correlated inversely with binding of PA to human exfoliated corneal epithelial cells after overnight and extended wear (R=0.258, P=0.0084); there was a significant decrease in surface epithelial cell desquamation and a significant increase in surface cell size following wear for all test lenses (P<0.05). Epithelial thinning was also observed following lens wear (P<0.05).
These results establish for the first time a significant correlation between contact lens-induced increases in epithelial PA binding and lens oxygen transmissibility in humans. New ultra-oxygen permeable test lenses did not appear to increase bacterial binding over individual control levels; all test lenses suppressed surface epithelial cell shedding. Taken together, these findings suggest that a new generation of contact lenses constructed from ultra-transmissible oxygen materials may offer a significant potential advance in safety for extended wear.
我们设计了一项为期3年的前瞻性、随机、盲法临床试验，以评估在单一中心人类过夜佩戴和长戴型隐形眼镜佩戴者中，隐形眼镜透氧性与细菌黏附于脱落的表面上皮细胞之间的关系；同时还测定了角膜细胞脱落率、表面上皮细胞大小和泪液乳酸脱氢酶（LDH）水平。
109名人类志愿者前瞻性地成功佩戴测试镜片并完成了本研究。评估了7种具有分层透氧性的软性镜片和3种硬性透气性（RGP）镜片。在适应日戴一周后，患者双侧持续佩戴测试镜片3个月，佩戴6晚，休息1晚。在连续佩戴隐形眼镜24小时、1个月和3个月前后，使用改良的角膜冲洗室收集脱落的表面上皮细胞。通过测量铜绿假单胞菌（PA）对脱落的角膜上皮细胞的黏附来确定细菌结合情况。使用荧光显微镜对黏附有细菌的脱落细胞数量进行计数。通过泪液LDH的变化以及使用体内串联扫描共聚焦显微镜（TSCM）测量表面上皮细胞大小和上皮厚度，进一步评估隐形眼镜佩戴对角膜表面的影响。结果测量的基线值作为个体患者的对照；同时还跟踪一组对照患者以监测季节性或可能的个体波动。
定量证据表明，在过夜佩戴和长戴后，镜片的物理透氧性特性而非镜片类型与PA与人脱落的角膜上皮细胞的结合呈显著负相关（R = 0.258，P = 0.0084）；所有测试镜片佩戴后表面上皮细胞脱落显著减少，表面细胞大小显著增加（P < 0.05）。佩戴镜片后还观察到上皮变薄（P < 0.05）。
这些结果首次证实了人类中隐形眼镜引起的上皮PA结合增加与镜片透氧性之间存在显著相关性。新型超透氧测试镜片似乎并未使细菌结合超过个体对照水平；所有测试镜片均抑制了表面上皮细胞脱落。综上所述，这些发现表明，由超透氧材料制成的新一代隐形眼镜在长戴安全性方面可能具有显著的潜在进展。
