Nicou Christina M, Passaglia Christopher L
Medical Engineering Department, University of South Florida, Tampa, Florida, United States.
Ophthalmology Department, University of South Florida, Tampa, Florida, United States.
Invest Ophthalmol Vis Sci. 2024 Aug 1;65(10):16. doi: 10.1167/iovs.65.10.16.
The purpose of this study was to determine the effects of ambient lighting on intraocular pressure (IOP) rhythmicity and variability.
IOP was continuously recorded by wireless telemetry from rats under light/dark (LD), dark/light (DL), asymmetric (6L18D and 18D6L), constant dark (DD), and constant light (LL) cycles. In some DD experiments, 1-hour light pulses were presented at varying times. IOP rhythmicity and variability were respectively quantified via cosinor analysis and peak detection algorithms that identified transient and sustained fluctuations.
Rat IOP peaked at night and troughed during the day with LD amplitude of 8.7 ± 3.4 mm Hg. Rhythmicity persisted in DD and LL with a free-running period of 24.1 ± 0.3 and 25.2 ± 0.4 hours, respectively. Peak-to-trough amplitude was approximately 60% smaller in LL, often disappeared after 1 to 2 weeks as daytime IOP drifted 2.6 ± 1.5 mm Hg higher, and returned to approximately 60% larger in LD. Rhythmicity was similarly impacted but resynchronized to DL over 4 to 6 days. Rhythmicity was unaltered by short photoperiods (6L18D), but the nocturnal IOP elevation was markedly shortened by long photoperiods (18L6D) and temporarily lowered to daytime levels by light pulses during the subjective night. Transient and sustained event rate, amplitude, interval, and energy content were nearly identical in LD, DD, and LL.
Aqueous humor dynamics of rat eyes are intrinsically configured to set IOP at daytime levels. Circadian clock input modulates these dynamics to elevate IOP at night. Light at night blocks this input, sending IOP back to daytime levels. Effects of abnormal lighting on IOP rhythmicity may contribute to pressure-related ocular neuropathies.
本研究旨在确定环境光照对眼压（IOP）节律性和变异性的影响。
通过无线遥测技术连续记录大鼠在明/暗（LD）、暗/明（DL）、不对称（6小时光照18小时黑暗和18小时黑暗6小时光照）、持续黑暗（DD）和持续光照（LL）周期下的眼压。在一些DD实验中，在不同时间给予1小时的光脉冲。通过余弦分析和识别瞬态和持续波动的峰值检测算法分别量化眼压的节律性和变异性。
大鼠眼压在夜间达到峰值，白天降至低谷，LD周期下的振幅为8.7±3.4毫米汞柱。DD和LL周期下节律性持续存在，自由运行周期分别为24.1±0.3小时和25.2±0.4小时。LL周期下的峰谷振幅约小60%，通常在1至2周后消失，因为白天眼压升高2.6±1.5毫米汞柱，而在LD周期下恢复到约大60%。节律性受到类似影响，但在4至6天内重新同步到DL周期。短光周期（6小时光照18小时黑暗）对节律性无影响，但长光周期（18小时光照6小时黑暗）使夜间眼压升高明显缩短，且在主观夜间通过光脉冲暂时降至白天水平。LD、DD和LL周期下的瞬态和持续事件发生率、振幅、间隔和能量含量几乎相同。
大鼠眼房水动力学本质上被配置为将眼压设定在白天水平。昼夜节律时钟输入调节这些动力学，使眼压在夜间升高。夜间光照阻断这种输入，使眼压回到白天水平。异常光照对眼压节律性的影响可能导致与压力相关的眼部神经病变。
