Instability of 24-hour intraocular pressure fluctuation in healthy young subjects: a prospective, cross-sectional study

• Published in: BMC ophthalmology Vol. 14; no. 1; p. 127
• Main Authors: Song, Yoo Kyung, Lee, Chang-Kyu, Kim, Jiwon, Hong, Samin, Kim, Chan Yun, Seong, Gong Je
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 04.11.2014; BioMed Central
• Subjects: Adult; Blood Pressure - physiology; Circadian Rhythm - physiology; Cross-Sectional Studies; Female; Healthy Volunteers; Humans; Intraocular Pressure - physiology; Ophthalmology; Posture; Prospective Studies; Reproducibility of Results; Tonometry, Ocular
• ISSN: 1471-2415; 1471-2415
• DOI: 10.1186/1471-2415-14-127

Elevated intraocular pressure (IOP) is a major risk factor for the development and/or progression of glaucoma, and a large diurnal IOP fluctuation has been identified as an independent risk factor of glaucoma progression. However, most previous studies have not considered the repeatability of 24-hour IOP measurements. The aim of this study was to evaluate the instability of 24-hour IOP fluctuations in healthy young subjects. Ten healthy young volunteers participated in this prospective, cross-sectional study. Each subject underwent 24-hour IOP and systolic/diastolic blood pressure (SBP/DBP) assessments both in sitting and supine positions every 3 hours, once a week for 5 consecutive weeks. Mean ocular perfusion pressure (MOPP) was then calculated for both positions. The intraclass correlation coefficients (ICCs) of maximum, minimum, and fluctuation parameters were computed for IOP, SBP/DBP, and MOPP. Fluctuation was defined as the difference between maximum and minimum values during a day. Among the serial measurements taken over a 24-hour rhythm, the maximum/minimum values of IOP, as well as BP, showed excellent agreement: regardless of position, all ICC values were over 0.800. Most of the BP fluctuation values also showed excellent agreement. IOP fluctuation, however, did not show excellent agreement; the ICC of sitting IOP fluctuation was just 0.212. MOPP fluctuation also showed poor agreement, especially in the sitting position (ICC, 0.003). On a day to day basis, 24-hour IOP fluctuations were not highly reproducible in healthy young volunteers. Our results imply that a single 24-hour IOP assessment may not be a sufficient or suitable way to characterize circadian IOP fluctuations for individual subjects.