title: Seasonal changes of 24-hour intraocular pressure rhythm in healthy Shanghai population.
abstract: The aim of the present study was to investigate and compare the 24-hour intraocular pressure (IOP) rhythms in winter and summer in the healthy population of Shanghai, China.This is a cross-sectional study in which 24-hour IOP measurements were taken for all eligible healthy volunteers in winter and summer, respectively, and the temperature, hours of sunlight (sunlight time), and circulatory parameters, including heart rate, systolic blood pressure, and diastolic blood pressure, were also recorded. The 24-hour IOP curves and IOP parameters (mean, peak, trough, and fluctuation of IOP together with the diurnal-to-nocturnal IOP change) in winter and summer were obtained and compared. The magnitude of IOP changes from summer to winter was also calculated.A total of 29 participants (58 eyes), 14 (48.28%) male and 15 (51.72%) female, aged 43.66 ± 12.20 (19-61) years, were considered eligible for this study. Generally, IOP decreased progressively before noon, increased notably in the nocturnal period, and peaked at 12:00 AM in winter and at 2:00 AM in summer. The pattern of 24-hour IOP in winter and summer was significantly different (P = 0.002). The average IOPs from 4:00 PM to 8:00 AM, except for 6:00 AM, were significantly higher in winter (P < 0.05). However, no significant differences were shown after adjusting for temperature and/or sunlight time. From summer to winter, the extent of IOP increase was mostly around 0 to 3 mm Hg, and the IOPs increased more significantly in the nocturnal period than in the diurnal period (P = 0.05).The 24-hour IOP rhythms were different in winter and summer, with higher IOP level in winter. Temperature and sunlight time, which are independent of heart rate and blood pressure, affected the 24-hour IOP rhythms in healthy people in Shanghai, China. Further investigations are expected for the rhythm of some endogenous substance secretion and the inner mechanism of regulation of IOP.
authors: Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Fudan University, Shanghai, China Key Laboratory of Myopia, Ministry of Health (Fudan University), Shanghai, China Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University Department of Ophthalmology, Shanghai Bei Zhan Hospital State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, China.
authors: Jingyi
authors: J
authors: Cheng
authors: Ming
authors: M
authors: Xiao
authors: Huan
authors: H
authors: Xu
authors: Shaobin
authors: S
authors: Fang
authors: Xu
authors: X
authors: Chen
authors: Xiangmei
authors: X
authors: Kong
authors: Xinghuai
authors: X
authors: Sun
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D012621:Seasons; D013472:Sunlight; D013696:Temperature; D014065:Tonometry, Ocular; D055815:Young Adult