Importance of the lipid layer in human tear film stability and evaporation
Importance of the lipid layer in human tear film stability and evaporation
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DOI：
10.1097/00006324-199701000-00014
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发表时间：
1997-01-01
影响因子：
1.4
通讯作者：
Tomlinson, A
中科院分区：
文献类型：
--
作者：
Craig, JP;Tomlinson, A
目的.以前对兔子的研究已经证明，当泪液脂质层被去除时，泪液蒸发增加了四倍。然而，体外研究表明，脂质层在延缓水层蒸发方面不起作用。在当前的研究中，通过测量相同个体的这些参数来确定脂质层在人泪膜稳定性和蒸发中的重要性。方法.对161例正常和干眼症受试者（男72例，女89例）的左眼进行了检查，年龄范围为13 ~ 85岁。泪液蒸发是从用改进的Servomed蒸发仪测量的蒸气压梯度导出的。脂质层结构和非侵入性破裂时间（NIBUT）进行了临床评估，通过镜面反射，与Keeler Tearscope。脂质层结构分为marmoreal（开放和封闭的网络），现在，无定形，彩色条纹（正常和异常）模式。这些观察到的图案反映了脂质层厚度。在整个实验过程中，环境温度和相对湿度保持相当恒定。结果泪液蒸发率发现不同的脂质层模式显着不同。没有可见脂质层或显示异常彩色条纹图案（在很少或没有脂质覆盖的区域中有脂质聚集）的眼睛显示出泪膜蒸发的显著更高速率（p < 0.001）。其余模式之间没有显着差异。还发现NIBUT随脂质层模式显著变化（p < 0.001），其中不存在或异常彩色条纹脂质模式表现出最差的稳定性。结论.在人脂质层不存在或不融合并且泪膜不稳定的情况下，泪液蒸发增加四倍。然而，在存在稳定、完整的脂质层的情况下，无论脂质厚度如何，泪液蒸发都被延迟。
Purpose. Previous work on rabbits has demonstrated a four-fold increase in tear evaporation when the tear lipid layer is removed. However, in vitro work has suggested that the lipid layer does not play a role in retarding evaporation of the aqueous layer. The importance of the lipid layer in human tear film stability and evaporation was determined in the current study by measurement of these parameters in the same individuals. Methods. The left eyes of 161 normal and dry eye subjects (72 males, 89 females), with an age range of 13 to 85 years, were examined. Tear evaporation was derived from the vapor pressure gradient measured with a modified Servomed evaporimeter. Lipid layer structure and noninvasive break-up time (NIBUT) were assessed clinically, by specular reflection, with the Keeler Tearscope. Lipid layer structure was categorized into marmoreal (open and closed meshwork), now, amorphous, and colored fringe (normal and abnormal) patterns. These observed patterns reflect lipid layer thickness. Ambient temperature and relative humidity remained fairly constant throughout the experiment. Results. Tear evaporation rate was found to vary significantly with different lipid layer patterns. Eyes with no visible lipid layer, or exhibiting an abnormal colored fringe pattern (with clumping of lipid amidst areas of little or no lipid cover), demonstrated a significantly higher rate of evaporation of the tear film (p < 0.001). There were no significant differences amongst the remainder of the patterns. The NIBUT was also found to vary significantly with lipid layer pattern (p < 0.001), with the absent or abnormal colored fringe lipid patterns exhibiting the poorest stability. Conclusions. Where the human lipid layer is absent, or is not confluent, and the tear film is unstable, tear evaporation is increased four-fold. However, where there is a stable, intact lipid layer, regardless of lipid thickness, tear evaporation is retarded.