Ladage Patrick M, Yamamoto Nobutaka, Robertson Danielle M, Jester James V, Petroll W Matthew, Cavanagh H Dwight
Department of Ophthalmology, University of Texas, Southwestern Medical Center at Dallas, Dallas, TX 75390-9057, USA.
Eye Contact Lens. 2004 Jul;30(3):173-8. doi: 10.1097/01.icl.0000133220.32701.c8.
To examine the effect of short-term 24-hr orthokeratology lens (OKL) wear on Pseudomonas aeruginosa binding, epithelial surface cell morphology, epithelial sheet thickness, and stromal thickness in a rabbit model.
Seventeen New Zealand white rabbits were treated according to the Association for Research in Vision and Ophthalmology Statement for the Use of Animals in Ophthalmic and Vision Research. Partial membranectomy was performed on all rabbits 1 week before the experiments. Baseline values for epithelial and stromal thickness and epithelial surface cell size were determined by in vivo confocal microscopy in one randomly chosen eye (n = 6). One week later, rabbits were fitted in the same eye with a hyper oxygen-transmissible OKL. Twenty-four hours later, confocal microscopy was repeated. The second group of rabbits (n = 6) was fitted with an OKL in one randomly chosen eye for 24 hr. P. aeruginosa binding to the corneal epithelium was assessed for the control corneas and those exposed to the test lens. Scanning electron microscopy was performed on a third group of rabbits to assess epithelial surface damage (n = 5).
There was a statistically significant difference (P<0.001) in P. aeruginosa binding between the control (1.11 +/- 0.74 x 10(5) colony-forming units per cornea) and the OKL-wearing eyes (2.74 +/- 0.69 x 10(5) colony-forming units per cornea). The central epithelium thinned by 6.5% after lens wear (48.2 +/- 1.9 microm to 45 +/- 1.7 microm, P=0.005); however, central stromal thickness increased by 7.3% (322 +/- 22 microm to 345 +/- 29 microm, P=0.006). Compared with the baseline value, central epithelial cell size increased significantly from 1,253 +/- 140 mm(2) to 1,627 +/- 393 mm(2) (29.4%, P=0.02). Scanning electron microscopy showed increased surface epithelial damage associated with OKL wear.
This prospective, masked, pilot study showed that 24-hr hyper oxygen-transmissible OKL wear induced a statistically significant increase in P. aeruginosa binding to the epithelium of the rabbit cornea, accompanied by central epithelial thinning, stromal thickening, and surface cell damage assessed by scanning electron microscopy. Collectively, the data suggest that despite adequate lens oxygen transmissibility, the mechanical pressure inherent in the OKL design exerted on the corneal surface appears to be associated with increased adherence of P. aeruginosa to surface corneal epithelial cells, which may pose an increased risk for lens-related microbial keratitis, especially in overnight (i.e., closed-eye) wearing conditions. Future studies are needed to determine whether these results are similar in human wear and how P. aeruginosa binding during OKL wear compares with other lens-wearing modalities, such as daily or continuous soft lens wear.
在兔模型中研究短期24小时佩戴角膜塑形镜（OKL）对铜绿假单胞菌黏附、上皮表面细胞形态、上皮层厚度和基质厚度的影响。
17只新西兰白兔按照视觉与眼科研究协会关于眼科和视觉研究中动物使用的声明进行处理。在实验前1周对所有兔子进行部分角膜切除术。通过体内共聚焦显微镜在一只随机选择的眼睛中测定上皮和基质厚度以及上皮表面细胞大小的基线值（n = 6）。1周后，在同一只眼睛中给兔子佩戴高透氧性OKL。24小时后，重复共聚焦显微镜检查。第二组兔子（n = 6）在一只随机选择的眼睛中佩戴OKL 24小时。评估对照角膜和接触测试镜片的角膜上铜绿假单胞菌与角膜上皮的黏附情况。对第三组兔子进行扫描电子显微镜检查以评估上皮表面损伤（n = 5）。
对照（每只角膜1.11±0.74×10⁵菌落形成单位）和佩戴OKL的眼睛（每只角膜2.74±0.69×10⁵菌落形成单位）之间铜绿假单胞菌黏附存在统计学显著差异（P<0.001）。佩戴镜片后中央上皮层变薄6.5%（从48.2±1.9微米降至45±1.7微米，P = 0.005）；然而，中央基质厚度增加了7.3%（从322±22微米增至345±29微米，P = 0.006）。与基线值相比，中央上皮细胞大小从1253±140平方毫米显著增加至1627±393平方毫米（29.4%，P = 0.02）。扫描电子显微镜显示与佩戴OKL相关的表面上皮损伤增加。
这项前瞻性、盲法、试点研究表明，24小时佩戴高透氧性OKL导致铜绿假单胞菌与兔角膜上皮的黏附在统计学上显著增加，同时伴有中央上皮变薄、基质增厚以及通过扫描电子显微镜评估的表面细胞损伤。总体而言，数据表明尽管镜片具有足够的透氧性，但OKL设计中固有的机械压力施加在角膜表面似乎与铜绿假单胞菌对角膜表面上皮细胞的黏附增加有关，这可能会增加与镜片相关的微生物性角膜炎的风险，尤其是在过夜（即闭眼）佩戴条件下。未来需要进行研究以确定这些结果在人类佩戴中是否相似，以及OKL佩戴期间铜绿假单胞菌的黏附与其他佩戴方式（如每日或连续佩戴软性镜片）相比如何。
