Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94720, United States.
Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States.
Cont Lens Anterior Eye. 2023 Aug;46(4):101850. doi: 10.1016/j.clae.2023.101850. Epub 2023 May 1.
With soft-contact-lens wear, evaporation of the pre-lens tear film affects the osmolarity of the post-lens tear film and this can introduce a hyperosmotic environment at the corneal epithelium, leading to discomfort. The purposes of the study are to ascertain whether there are differences in evaporation flux (i.e., the evaporation rate per unit area) between symptomatic and asymptomatic soft-contact-lens wearers, to assess the repeatability of a flow evaporimeter, and to assess the relationship between evaporation fluxes, tear properties, and environmental conditions.
Closed-chamber evaporimeters commonly used in ocular-surface research do not control relative humidity and airflow, and, therefore, misestimate the actual tear-evaporation flux. A recently developed flow evaporimeter overcomes these limitations and was used to measure accurate in-vivo tear-evaporation fluxes with and without soft-contact-lens wear for symptomatic and asymptomatic habitual contact-lens wearers. Concomitantly, lipid-layer thickness, ocular-surface-temperature decline rate (i.e., °C/s), non-invasive tear break-up time, tear-meniscus height, Schirmer tear test, and environmental conditions were measured in a 5 visit study.
Twenty-one symptomatic and 21 asymptomatic soft-contact-lens wearers completed the study. A thicker lipid layer was associated with slower evaporation flux (p < 0.001); higher evaporation flux was associated with faster tear breakup irrespective of lens wear (p = 0.006). Higher evaporation flux was also associated with faster ocular-surface-temperature decline rate (p < 0.001). Symptomatic lens wearers exhibited higher evaporation flux than did asymptomatic lens wearers, however, the results did not reach statistical significance (p = 0.053). Evaporation flux with lens wear was higher than without lens wear but was also not statistically significant (p = 0.110).
The repeatability of the Berkeley flow evaporimeter, associations between tear characteristics and evaporation flux, sample-size estimates, and near statistical significance in tear-evaporation flux between symptomatic and asymptomatic lens wearers all suggest that with sufficient sample sizes, the flow evaporimeter is a viable research tool to understand soft-contact-lens wear comfort.
软性隐形眼镜佩戴者的镜片前泪膜蒸发会影响镜片后泪膜的渗透压，这会导致角膜上皮处于高渗环境，从而引起不适。本研究旨在确定有症状和无症状软性隐形眼镜佩戴者之间蒸发通量（即单位面积的蒸发速率）是否存在差异，评估流量蒸发器的可重复性，并评估蒸发通量、泪液特性和环境条件之间的关系。
眼表研究中常用的封闭式腔蒸发器不能控制相对湿度和气流，因此会错误估计实际的泪液蒸发通量。最近开发的流量蒸发器克服了这些限制，用于测量有症状和无症状习惯性隐形眼镜佩戴者佩戴和不佩戴软性隐形眼镜时的准确体内泪液蒸发通量。同时，在 5 次就诊中测量了脂质层厚度、眼表面温度下降率（即°C/s）、非侵入性泪膜破裂时间、泪膜高度、泪液分泌试验和环境条件。
21 名有症状和 21 名无症状软性隐形眼镜佩戴者完成了这项研究。较厚的脂质层与较慢的蒸发通量相关（p<0.001）；无论佩戴隐形眼镜与否，较高的蒸发通量与更快的泪膜破裂相关（p=0.006）。较高的蒸发通量也与较快的眼表面温度下降率相关（p<0.001）。有症状的隐形眼镜佩戴者的蒸发通量高于无症状的隐形眼镜佩戴者，但结果没有达到统计学意义（p=0.053）。佩戴隐形眼镜时的蒸发通量高于不佩戴隐形眼镜时，但也没有统计学意义（p=0.110）。
Berkeley 流量蒸发器的可重复性、泪液特性与蒸发通量之间的关系、样本量估计以及有症状和无症状隐形眼镜佩戴者之间的泪液蒸发通量接近统计学意义，都表明在有足够样本量的情况下，流量蒸发器是一种可行的研究工具，可以帮助我们了解软性隐形眼镜佩戴的舒适度。
