Abstract
Purpose: :
To investigate IOP differences between regular office visits and serial laboratory measurements.
Methods: :
IOP of 31 individuals (62 eyes) was measured in the office with Goldmann tonometry. During a second visit IOP was taken at the same time of day in our 24 hour sleep laboratory in the sitting position using a calibrated pneumatonometer. Height and weight were recorded and the body mass index (BMI) was calculated. Office and laboratory IOP were compared. IOP of overweight and obese patients (BMI > 25) was compared to IOP of patients with normal or low BMI. BMI of patients with IOP above 21 mm Hg was compared to BMI of patients with IOP below 21 mm Hg.
Results: :
Office IOP was significantly higher than laboratory IOP (20.2 +/- 4.3 mm Hg versus 17.4 +/- 2.7 mm Hg, p = 5.7E-08) with a mean difference of 3.0 +/- 3.6 mm Hg. Office IOP was 2.3 mm Hg higher in subjects with a BMI above 25 (p = 0.025) compared to normal BMI subjects but was not significantly different in laboratory pneumatonometry measurements. Linear regression analysis showed an office IOP increase of 1.25 mm Hg per 5 BMI. Patients with an IOP >/= 21 mm Hg had a higher BMI (p = 0.033).
Conclusions: :
In overweight and obese individuals office Goldmann IOP is higher than pneumatonometry IOP. This difference could be caused by increased intra-abdominal pressure when leaning forward at the slit lamp during IOP measurement.
Keywords: intraocular pressure • clinical laboratory testing