探讨急性低压缺氧暴露对健康人群干眼参数中泪膜稳定性的影响。

选取2023年10月至2024年10月期间从北京航空航天大学招募的健康志愿者22名(44只眼)作为研究对象。其中，男性12名(24只眼)，女性10名(20只眼)；年龄20~24岁，平均年龄(22.3±1.5)岁。受试者在低压模拟舱内分别于地面50 m、3500 m、4000 m、4500 m及返回地面接受泪膜稳定性检测。采用眼表干涉仪检测泪膜破裂时间(TBUT)、泪膜脂质层厚度(LLT)、泪河高度(TRH)及完全瞬目次数。采用Shapiro-Wilk检验对所有数据进行正态性检验，TRH、TBUT符合正态分布以±s表示，LLT及完全瞬目次数不符合正态分布，以极差的中位数或四分位极差(IQR)表示。不同海拔高度对各项指标之间差异性检验采用广义线性混合模型(GLMM)分析，对正态分布数据事后两两比较采用Bonferroni校正，非正态分布数据采用Wilcoxon符号秩检验。

所有受试者均在未接受额外氧气补充的情况下完成了整个流程试验。所有受试者在海拔约50 m地面水平、3500 m、4000 m、4500 m及返回地面时TBUT、TRH、LLT以及瞬目次数分别为(9.89±2.60)s、(0.19±0.09)mm、56.16(41.00，66.00)nm、2(2，2)次、(9.28±2.47)s、(0.22±0.11)mm、55.71(41.00，66.00)nm、2(2，2)次、(7.57±2.86)s、(0.18±0.10)mm、55.43(41.00，66.00)nm、2(2，3)次、(7.94±3.07)s、(0.22±0.13)mm、55.53(41.00，66.00)nm、3(2，3)次、(9.50±2.74)s、(0.17±0.08)mm、50.61(41.00，66.00)nm及2(2，2)次。随着海拔高度的增加，TBUT整体上呈现下降趋势，尤其是在4500 m重度缺氧状态下，TBUT达到最短。当海拔高度下降，受试者返回地面时，TBUT再次增加，逐渐恢复到接近初次地面水平。LLT随着海拔的逐渐升高经历了先增后减。当受试者从高海拔地区回到地面时，LLT并未恢复，而出现较为明显的下降。TRH随海拔高度变化显示出一定的波动性。经Bonferroni校正分析，受试者初次地面时的TBUT长于海拔3500 m、海拔4000 m及4500 m下的TBUT，差异有统计学意义(P<0.05)；而3500 m处的TBUT长于4000 m及4500 m，差异有统计学意义(P<0.05)。在海拔4000 m和4500 m时受试者TBUT短于回到地面时，差异有统计学意义(P<0.05)。随着海拔升高，与初次地面处相比，LLT在海拔3500 m和海拔4000 m时呈下降趋势，在到达4500 m时略有升高。经Wilcoxon符号秩检验，在海拔3500 m、海拔4000 m及4500 m下的LLT值与初次地面高度相比，差异均无统计学意义(Z＝-0.871，-0.443，-0.678；P>0.05)。此外，双眼LLT在回到地面后薄于初次地面状态、海拔3500 m、海拔4000 m及4500 m的LLT值，差异有统计学意义(Z＝-2.975，-2.725，-2.356，-2.465；P<0.05)。经Bonferroni校正分析，初次地面、4000 m及返回地面时，TRH分布相对均匀，而在3500 m时波动较大。此外，采用GLMM比较不同条件下TRH的差异，结果显示与初次地面状态相比，3500 m时TRH升高，差异有统计学意义(P<0.05)；与3500 m相比，4000 m时TRH下降，差异有统计学意义(P<0.05)，4500 m时TRH升高，差异有统计学意义(P<0.05)；同时与回到地面相比，TRH再次下降，差异有统计学意义(P<0.05)。受试者在地面时20 s内完全瞬目次数为2次，随着海拔升高，在4000 m和4500 m时增加至3次。4500 m处时受试者的完全瞬目次数与地面、4000 m以及返回地面相比差异均有统计学意义(Z＝-1.999，-2.238，-2.586，P<0.05)。此外，4000 m的完全瞬目次数与返回地面时相比差异有统计学意义(Z＝-2.015，P<0.05)。

急性低压低氧暴露可引起泪膜相关参数的早期功能性改变，主要表现为泪膜稳定性下降及瞬目行为改变，而泪液体积受影响较小。泪膜相关指标对急性低氧刺激较为敏感，可为高海拔及航空作业人群干眼风险的早期评估提供客观依据。

To investigate the effects of short-term acute hypobaric hypoxia on tear film stability in healthy subjects.

A total of 22 healthy volunteers (44 eyes) recruited from Beihang University between October 2023 and October 2024 were enrolled as study subjects. Among them, there were 12 males (24 eyes) and 10 females (20 eyes) with a mean age of (22.3±1.5) years (ranging from 20 to 24 years). Subjects underwent tear film stability measurements in a hypobaric chamber at ground level (50 m), 3500 m, 4000 m, 4500 m, and after returning to ground level. Tear breakup time (TBUT), tear film lipid layer thickness (LLT), tear meniscus height (TRH), and complete blink counts were measured using an ocular surface interferometer. The Shapiro-Wilk test was used to assess normality for all data. TRH and TBUT were normally distributed and expressed as ±s; LLT and complete blink counts were non-normally distributed and expressed as median (interquartile range [IQR]). Differences in parameters across different altitudes were analyzed using the Generalized Linear Mixed Model (GLMM). Post-hoc pairwise comparisons for normally distributed data were performed using Bonferroni correction, and the Wilcoxon signed-rank test was used for non-normally distributed data.

All subjects completed the entire experimental procedure without supplemental oxygen. The values of TBUT, TRH, LLT, and complete blink counts at sea level (approximately 50 m), 3500 m, 4000 m, 4500 m and after returning to ground level were (9.89±2.60) s, (0.19±0.09) mm, 56.16 (41.00, 66.00) nm, 2 (2, 2) times, (9.28±2.47) s, (0.22±0.11) mm, 55.71 (41.00, 66.00) nm, 2 (2, 2) times, (7.57±2.86) s, (0.18±0.10) mm, 55.43 (41.00, 66.00) nm, 2 (2, 3) times, (7.94±3.07) s, (0.22±0.13) mm, 55.53 (41.00, 66.00) nm, 3 (2, 3) times, (9.50±2.74) s, (0.17±0.08) mm, 50.61 (41.00, 66.00) nm, and 2 (2, 2) times, respectively.With increasing altitude, TBUT showed an overall decreasing trend, reaching the shortest value at 4500 m under severe hypoxic conditions. When the altitude decreased and subjects returned to ground level, TBUT increased again, gradually recovering to near baseline levels. LLT exhibited a trend of initial thickening followed by reduction as altitude gradually increased. When subjects returned to ground level from high altitude, LLT did not recover but showed the decrease instead. TRH showed certain fluctuations with changes in altitude. After Bonferroni correction, TBUT at baseline was longer than that at 3500 m, 4000 m, and 4500 m with significant difference (P<0.05). TBUT at 3500 m was longer than that at 4000 m and 4500 m with significant difference (P<0.05). At 4000 m and 4500 m, TBUT was shorter than that after returning to ground level with significant difference (P<0.05). With increasing altitude, compared to ground level, LLT showed a decreasing trend at 3500 m and 4000 m, with a slight increase at 4500 m. There were no statistically significant differences in LLT values at 3500 m, 4000 m, and 4500 m compared to ground level (P>0.05). Additionally, binocular LLT after returning to ground level was thinner than baseline values and values at 3500 m, 4000 m and 4500 m with significant difference (P<0.05). After Bonferroni correction, TRH distribution was relatively uniform at ground level, 4000 m, and after returning to ground level, but showed greater fluctuation at 3500 m. Furthermore, GLMM analysis comparing TRH under different conditions showed that TRH at 3500 m was higher than baseline with significant difference (P<0.05); compared to 3500 m, TRH at 4000 m was significantly decreased (P<0.05), while TRH at 4500 m was increased with significant difference (P<0.05); and TRH was decreased again after returning to ground level compared to 4500 m with significant difference (P<0.05). The number of complete blinks within 20 s was 2 at ground level, increasing to 3 at 4000 m and 4500 m as altitude increased. At 4500 m, the number of complete blinks was statistically significantly different compared to ground level, 4000 m, and after returning to ground level (Z=-1.999, -2.238, -2.586; P<0.05). Additionally, the number of complete blinks at 4000 m was statistically significantly different compared to after returning to ground level (Z=-2.015, P<0.05).

Short-term acute hypobaric hypoxia induces early functional changes in tear film-related parameters, characterized mainly by reduced tear film stability and altered blinking behavior, while tear volume remains relatively unaffected. Tear film-related indicators are sensitive to acute hypoxic stimuli and may provide objective evidence for early assessment of dry eye risk in high-altitude and aviation-related populations.