Evaluation of the effect of daily activities on intraocular pressure in healthy people: is the 20 mmHg border safe?
OBJECTIVE To determine the effect of eyelid manipulation and manual jugular compression on intraocular pressure (IOP) measurement in clinically normal dogs. DESIGN Randomized clinical trial. ANIMALS 30 dogs (57 eyes) without diseases or medications that affect IOP. PROCEDURES An applanation tonometer was used to measure IOP during eyelid manipulation or jugular compression. Six manipulations were used in each eye, including minimal eyelid manipulation, maximal dorsoventral extension of the eyelids, lateral eyelid extension, manual compression of the ipsilateral jugular vein, manual compression of both jugular veins, and lateral eyelid extension with manual compression of both jugular veins. Skull type and position of globe in the orbit were recorded. RESULTS The 2 manipulations that caused the greatest significant increase in mean IOP were lateral eyelid extension with compression of both jugular veins (difference from baseline IOP, 17.6 mm Hg; 95% confidence interval [CI], 15.7 to 19.5 mm Hg) and lateral eyelid extension alone (16.5 mm Hg; 95% CI, 14.6 to 18.4 mm Hg). Dorsoventral eyelid extension (6.42 mm Hg; 95% CI, 4.5 to 8.3 mm Hg) and compression of both jugular veins alone (3.0 mm Hg; 95% CI, 1.1 to 5.0 mm Hg) significantly increased mean IOP, compared with baseline. Compression of the ipsilateral jugular vein increased mean IOP (0.3 mm Hg; 95% CI, -1.6 to 2.2 mm Hg) from baseline, but not significantly. CONCLUSIONS AND CLINICAL RELEVANCE Traction on the eyelids or pressure on both jugular veins can significantly increase IOP values as measured by use of applanation tonometry in clinically normal dogs.