荧光和泪膜脂质层图像同步录像研究泪膜破裂和结构。
Tear film breakup and structure studied by simultaneous video recording of fluorescence and tear film lipid layer images.
机构信息
College of Optometry, The Ohio State University, Columbus, Ohio 43210, USA.
出版信息
Invest Ophthalmol Vis Sci. 2013 Jul 22;54(7):4900-9. doi: 10.1167/iovs.13-11878.
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 μL2% 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.
目的
眨眼间及泪膜破裂时的预角膜泪膜变薄可合理地分析为三个组成部分的贡献：蒸发、流入角膜、以及沿角膜表面的切向流动。虽然发散的切向流动有助于某些类型的破裂，但有人认为蒸发是泪膜变薄和破裂的主要原因。由于蒸发受泪膜脂质层（TFLL）控制，因此应该期望破裂模式与 TFLL 中的模式相匹配，本研究检验了这一假设。
方法
描述了一种用于同时视频成像荧光素泪膜破裂和 TFLL 的光学系统。从 85 名受试者（包括健康和干眼症患者）中进行了记录。在滴注 5μL2%荧光素后，受试者在记录开始后 1 秒眨眼，并尝试保持眼睛睁开 30 或 60 秒。
结果
泪膜变薄和破裂的区域通常与 TFLL 的相应特征相匹配。虽然变薄和破裂通常与薄脂质相匹配，但令人惊讶的是，相应的脂质区域并不总是比周围的脂质薄。偶尔，由于切向汇聚流，薄脂质区域会导致相应区域的荧光增强（较厚的水层）。
结论
如果破裂主要是由于蒸发引起的，那么泪膜变薄和破裂的区域通常可以与 TFLL 的相应区域相匹配。令人惊讶的是，在某些情况下，相应的脂质区域没有变薄，甚至可能比周围的脂质更厚。这表明脂质作为蒸发的屏障很差，可能是由于组成和/或结构的缺陷。例如，细菌脂酶可能已经将酯分解成成分酸和醇，导致 TFLL 结构缺陷，蒸发增加。
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