[Posture-induced intraocular pressure measurements].

OBJECTIVE: To measure the intraocular pressure (IOP) in different sleep positions and compare with IOP in the sitting position. METHODS: Perspective study. Thirty-two patients with primary open angle glaucoma (POAG) and 28 normal subjects had IOP measured in the sitting position and then again in the supine, right lateral decubitus (right-lateral) and left lateral decubitus (left-lateral) positions with a Perkins applanation tonometer. IOPs then were measured again in the sitting postion after 1, 5 and 10 minutes. Two-way ANOVA was used to compare IOP readings in the different positions among the two study groups. Data were shown as mean ± standard deviation. RESULTS: In normal subjects, the IOP values of the right eye were (17.5 ± 3.8) (sitting), (19.3 ± 3.1) (supine), (21.7 ± 3.7) (right-lateral) and (21.5 ± 3.7) mmHg (left lateral) (1 mmHg = 0.133 kPa). The IOP values of left eye were (18.4 ± 3.0) (sitting), (19.3 ± 3.1) (supine), (20.7 ± 2.9) (right-lateral) and (22.8 ± 4.0) mmHg (left lateral). In the POAG patients, the IOP values of the right eye were (17.9 ± 3.7) (sitting), (20.6 ± 4.6) (supine), (26.1 ± 7.1)(right-lateral) and (26.3 ± 5.9) mmHg (left-lateral). The IOP of the left eye in these positions were (18.2 ± 3.6),(20.0 ± 4.1), (25.6 ± 6.1) and (25.7 ± 6.0) mmHg, respectively. The IOP under the right- and left-lateral positions were higher than that in sitting and supine in both groups. The IOP increases in all positions for POAG patients were significant higher than in normal subjects. The IOP decreased rapidly after returning from the supine to the sitting position. The IOP values at 1 minute, 5 minutes and 10 minutes after returning to the sitting position were not significantly different than the original sitting. CONCLUSIONS: The IOP in lateral decubitus positions is significantly higher than the IOP in sitting and supine positions. These differences are greater in POAG.