Liu Qiong, McDermott Alison M, Miller William L
College of Optometry, University of Houston, Houston, TX 77204-2020, USA.
Eye Contact Lens. 2009 Sep;35(5):232-7. doi: 10.1097/ICL.0b013e3181b3e87f.
Nerve growth factor (NGF) has been shown to be upregulated in conditions, which damage corneal nerves and to relieve dry eye. How NGF changes in nerve injury induced by established contact lens wear is not clear. The purpose of this study was to measure the subepithelial nerve plexus and tear NGF and transforming growth factor (TGF)-beta1 levels in patients with established contact lens associated with dry eye.
Non-contact lens wearers and subjects who had worn soft contact lenses for more than 1 year were recruited and were divided into three groups: (1) normal controls; (2) contact lens wearers without dry eye; (3) contact lens wearers with dry eye. Corneal sensitivity was measured with a Cochet-Bonnet aesthesiometer. Nerve density and branching in the subepithelial plexus were measured using in vivo confocal microscopy. Tear NGF and TGF-beta1 levels were measured with an enzyme immuno assay.
There was a statistically significant decrease of corneal sensitivity in contact lens wearers compared with normal controls. The nerve density in the subepithelial plexus of contact lens wearers with dry eye was 538.8 +/- 39.3 microm/image (3.959 +/- 0.28 pm/microm(2)) and 537.1 +/- 30.9 microm/image (3.947 +/- 0.27 pm/microm(2)) in those without dry eye. Both of these values were significantly (P=0.032) lower than in the normal controls (4.412 +/- 0.21 pm/microm(2)). The concentration of tear NGF was increased in contact lens wearers with dry eye and was statistically significantly greater compared with contact lens wearers without dry eye. Transforming growth factor-beta1 levels were found to increase one fold in contact lens associated dry eye, and were significantly correlated to NGF.
Corneal subepithelial nerve density was decreased in long-term contact lens wear but this change was not significantly correlated with tear film NGF concentration. Tear film NGF levels were elevated in contact lens related dry eye, likely in response to anti-inflammatory factors such as TGF-beta1.
神经生长因子（NGF）已被证明在损伤角膜神经的情况下会上调，并可缓解干眼。目前尚不清楚在长期佩戴隐形眼镜引起的神经损伤中NGF是如何变化的。本研究的目的是测量长期佩戴隐形眼镜且伴有干眼患者的上皮下神经丛、泪液NGF及转化生长因子（TGF）-β1水平。
招募非隐形眼镜佩戴者和佩戴软性隐形眼镜超过1年的受试者，并将其分为三组：（1）正常对照组；（2）无干眼的隐形眼镜佩戴者；（3）有干眼的隐形眼镜佩戴者。使用Cochet-Bonnet麻醉计测量角膜敏感性。采用活体共聚焦显微镜测量上皮下神经丛的神经密度和分支情况。使用酶免疫分析法测量泪液NGF和TGF-β1水平。
与正常对照组相比，隐形眼镜佩戴者的角膜敏感性有统计学意义的降低。有干眼的隐形眼镜佩戴者上皮下神经丛的神经密度为538.8±39.3微米/图像（3.959±0.28皮米/微米²），无干眼的为537.1±30.9微米/图像（3.947±0.27皮米/微米²）。这两个值均显著低于正常对照组（4.412±0.21皮米/微米²）（P = 0.032）。有干眼的隐形眼镜佩戴者泪液NGF浓度升高，与无干眼的隐形眼镜佩戴者相比有统计学意义上的显著升高。发现TGF-β1水平在隐形眼镜相关性干眼中增加了一倍，且与NGF显著相关。
长期佩戴隐形眼镜会导致角膜上皮下神经密度降低，但这种变化与泪膜NGF浓度无显著相关性。在隐形眼镜相关性干眼中泪膜NGF水平升高，可能是对诸如TGF-β1等抗炎因子的反应。
