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Carolina S Freitas, Sebastiao Cronemberger, Ligia P Gualberto, Christy Veiga, Erica A Borges, Alberto Diniz-Filho, Nassim S Calixto; Postural and Sleeping Effects on Intraocular Pressure. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6432.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate correlation and agreement between intraocular pressure (IOP) measurements during a daily curve of intraocular pressure (DCPo) in different periods of the day and the effects of body position and sleeping period.
The DCPo performed in the Glaucoma Division of Hospital Sao Geraldo consisted in measurements obtained in the sitting position using Goldmann tonometer at 9 am, 11 am, 6 pm, and 10 pm. After being hospitalized during the night, IOP measurements at 6 am were performed using a Perkins tonometer upon awaking in a supine position before getting out of the bed and in a dark room. For the present study, it was proposed an additional measurement at 7 pm performed one hour after remained in a supine position using also Perkins tonometer in a dark room. The IOP measurements were compared using a paired t-test and peak was determined when IOP>21 mmHg. Agreement between the messurements was assessed using Bland-Altman plots. Generalized estimating equations models were used to investigate the relationship between IOP measurements, taking into account the correlation between fellow eyes.
One hundred and twelve eyes of 59 suspect and glaucoma patients were included in this study. Mean age was 64.4 ± 15.4 years. The mean IOP at 6 am in a supine position was statistically higher than that that measured at 7 pm (19.4 ± 4.4 mmHg vs. 17.7 ± 5.2 mmHg; P=0.001). The mean IOP at 6 pm had an average of 13.0 ± 2.7 and was statistically lower than that measured at 6 am (P<0.001). Association between IOP both in the supine position at 6 am and 7 pm was weak (R2=14%; P=0.069). Association between IOP at 6 pm and 7 pm was even weaker (R2=6%; P=0.438). Mean difference between measurements at 6 am and 7 pm in the supine position was 1.7 (95% CI 0.7 to 2.7) mmHg. Mean difference between measurements at 7 pm in the supine position and 6 pm in the sitting position was 4.7 (95% CI 3.7 to 5.7) mmHg. Thirty one eyes (28%) had peak (IOP>21 mmHg) at 6 am and the same amount at 7 pm. From those, only 17 had peak both 6 am and 7 pm.
Association and agreement among IOP measurements in the supine position taken at 6 am upon awaking in a dark room and at 7 pm were poor. Postural effect in a supine position resulting in increased episcleral venous pressure seems to be an effect on IOP increase. However, other factors during sleep are responsible for the circadian elevation of IOP.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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