Untreated 24-Hour Intraocular Pressure Measured by Goldmann Applanation Tonometry Compared to Nightime Supine Pressures With Perkins' Applanation Tonometry

Purpose:To use Perkins’ applanation tonometry to measure supine nighttime intraocular pressures and to compare these values to sitting day and nighttime Goldmann applanation intraocular pressures. Methods:Prospective, untreated, uncontrolled, observational cohort. Qualified patients underwent an appropriate washout period of their current ocular hypotensive medications. Patients with pressures of 22 mm Hg at 10:00, in at least one eye, underwent pressure measurements over 24 hours at 10:00, 14:00, 18:00, 22:00, 02:00 and 06:00 by Goldmann applanation tonometry in a sitting position. In addition, patients had their pressures measured at 10:00, 22:00, 02:00 and 06:00 by Perkins’ applanation tonometry in a supine position Results:In total, 100 patients completed the study. The mean intraocular pressures at 10:00, 22:00, 02:00 and 06:00, while sitting was 23.1±3.6 ,and in the supine position, 23.5±4.3 (P<0.001). Further, the difference in pressure was significantly different between sitting and supine groups at 3 individual time points (10:00, 22:00, 02:00, P0.006) but not at 06:00 (P=0.30). Glaucoma patients (n=35) had a mean change of 22.7±3.5 to 23.6±4.0 mmHg, while ocular hypertensives (n=65) had a mean change of 22.5±3.6 to 23.4±4.4 mmHg, moving from a sitting to a supine position (P=0.07). The mean sitting Goldmann intraocular pressures across the three diurnal time points (10:00, 14:00 and 18:00) was 23.9±6.2 and across the three night time points (22:00, 02:00 and 06:00) was 21.4±0.2(P<0.001). In contrast, the mean daytime sitting Goldmann pressures were not statistically different than nighttime supine Perkins’ pressures (22.8±4.4,P=0.07). However, only 90% of patients were within 5.7 mmHg of the highest daytime reading for all nighttime supine and sitting pressures. Conclusions:This study suggests that by Goldmann applanation tonometry, untreated supine or sitting intraocular pressures are not higher at night than daytime sitting pressures. However, the highest daytime sitting pressures do not predict well the highest nighttime sitting or supine pressure values.