Tear Film Breakup and Structure Studied by Simultaneous Video Recording of Fluorescence and Tear Film Lipid Layer Images
Tear Film Breakup and Structure Studied by Simultaneous Video Recording of Fluorescence and Tear Film Lipid Layer Images
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DOI：
10.1167/iovs.13-11878
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发表时间：
2013-07-01
影响因子：
4.4
通讯作者：
Nichols, Kelly K.
中科院分区：
文献类型：
--
作者：
King-Smith, P. Ewen;Reuter, Kathleen S.;Nichols, Kelly K.
目的。眨眼之间角膜前泪膜变薄和泪膜破裂可以从逻辑上分析为三个组成部分的贡献：蒸发、流入角膜和沿角膜表面的切向流。尽管发散切向流会导致某些类型的破裂，但有人认为蒸发是泪液变薄和破裂的主要原因。由于蒸发是由泪膜脂质层 (TFLL) 控制的，因此应该预期破裂模式应与 TFLL 中的模式相匹配，并且该假设在本研究中得到了检验。方法。描述了一种用于荧光素泪膜破裂和 TFLL 同步视频成像的光学系统。对 85 名受试者进行了记录，其中包括健康眼睛和干眼受试者。滴注5μL2%荧光素后，要求受试者在记录开始后眨眼1秒，并在30秒或60秒的记录长度内尽量保持睁眼。 结果。泪膜变薄和破裂的区域通常与 TFLL 中的相应特征相匹配。尽管变薄和破裂通常与稀薄的脂质相匹配，但令人惊讶的是，相应的脂质区域并不总是比周围的脂质更薄。有时，由于会聚切向流，较薄的脂质区域会导致相应的较大荧光区域（较厚的水层）。结论。泪液变薄和破裂的区域通常可以与 TFLL 的相应区域相匹配，如果破裂主要是由于蒸发，则可以预期这一点。令人惊讶的是，在一些例子中，相应的脂质区域并不比周围的脂质更薄，而且可能更厚。这表明脂质对于蒸发的屏障作用较差，可能是因为成分和/或结构的缺陷。例如，细菌脂肪酶可能将酯分解成酸和醇，导致 TFLL 结构有缺陷，蒸发增加。
PURPOSE. The thinning of the precorneal tear film between blinks and tear film breakup can be logically analyzed into contributions from three components: evaporation, flow into the cornea, and tangential flow along the corneal surface. Whereas divergent tangential flow contributes to certain types of breakup, it has been argued that evaporation is the main cause of tear thinning and breakup. Because evaporation is controlled by the tear film lipid layer (TFLL) it should therefore be expected that patterns of breakup should match patterns in the TFLL, and this hypothesis is tested in this study.METHODS. An optical system is described for simultaneous video imaging of fluorescein tear film breakup and the TFLL. Recordings were made from 85 subjects, including both with healthy and dry eyes. After instillation of 5 mu L2% fluorescein, subjects were asked to blink 1 second after the start of the recording and try to maintain their eyes open for the recording length of 30 or 60 seconds.RESULTS. Areas of tear film thinning and breakup usually matched corresponding features in the TFLL. Whereas thinning and breakup were often matched to thin lipid, surprisingly, the corresponding lipid region was not always thinner than the surrounding lipid. Occasionally, a thin lipid region caused a corresponding region of greater fluorescence (thicker aqueous layer), due to convergent tangential flow.CONCLUSIONS. Areas of tear thinning and breakup can generally be matched to corresponding regions of the TFLL as would be expected if breakup is largely due to evaporation. Surprisingly, in some examples, the corresponding lipid area was not thinner and possibly thicker than the surrounding lipid. This indicates that the lipid was a poor barrier to evaporation, perhaps because of deficiency in composition and/or structure. For example, bacterial lipases may have broken down esters into component acids and alcohols, causing a defective TFLL structure with increased evaporation.