Clinical study of 24-hour intraocular pressure curve measurement strategy

Background To investigate the measurement time of 24-hour intraocular pressure(IOP) curve: the representativeness of 4 and 6 times IOP to the fluctuation of IOP at night and day. Methods From September 2018 to January 2019, 41 patients with suspected primary open angle glaucoma(POAG), who were admitted to the Department of Ophthalmology, Peking University International Hospital, underwent 24-hour IOP monitoring. The measuring time points were set as: 0:00, 2:00, 5:00, 7:00, 8:00, 10:00, 11:00, 14:00, 16:00, 18:00, 20:00 and 22:00, of which 8:00, 11:00, 14:00, 16:00 were the customary measuring time of IOP daily curve for 4 times; 5:00, 7:00, 10:00, 14:00, 18:00, 22:00 were the conventional measuring time points for IOP curve for 6 times. The time points of the two groups was increased by 0:00, 2:00 and 20:00 to 12 times IOP measurements. Goldmann tonometer was used to measure IOP . Oxybuprocainehydrochloride eye drops were anesthetized by the same ophthalmologist. The sensitivity of the two methods to detect 24-hour intraocular pressure fluctuations was calculated according to whether the peak values of 12 times IOP measurements could be included by 4 or 6 times IOP measurements. Results A total of 41 patients (82 eyes) were enrolled, including 21 males (42 eyes) and 20 females (40 eyes). The age ranged from 23 to 77（44.60±14.67）. The peak IOP measured by 4 times, 6 times and 12 times IOP measurements were 19.91±4.38mmHg、 20.54±4.10 mmHg and 21.09±4.15 mmHg respectively, and there were significant differences between the two methods (P < 0.05); the trough values of IOP were 15.46±3.63 mmHg 、14.63±3.49 mmHg and 13.93±3.38 mmHg respectively, with statistical significance (P < 0.05). The peak IOP co-occurrence is 74.39% between 6 times and 12 times IOP measurements. The peak IOP co-occurrence is 43.90% between 4 times and 12 times IOP measurements. The sensitivity of 4 and 6 times IOP measurements to detect 24-hour IOP fluctuations were 36.11% and 55.56%, respectively. Conclusion For suspected glaucoma patients, neither 4 times IOP measurements nor 6 times IOP measurements during a day can accurately reflect the range of IOP fluctuations, which may easily lead to missed diagnosis.