Effect of a tight necktie on intraocular pressure

Aim: To evaluate the effect of a tight necktie on intraocular pressure (IOP) measurement using Goldmann applanation tonometry. Methods: 40 eyes of 20 normal subjects and 20 open angle glaucoma patients ( all male) were enrolled. IOP was measured with an open shirt collar, 3 minutes after placing a tight necktie, and 3 minutes after loosening it. All measurements were made by the same examiner. Results: Mean IOP in normal subjects increased by 2.6 (SD 3.9) mm Hg (p = 0.008, paired t test; range - 3 to + 14 mm Hg) and in glaucoma patients by 1.0 ( 1.8) mm Hg (p = 0.02, paired t test; range - 2 to + 4.5 mm Hg). In normal subjects, IOP in 12 eyes was increased by greater than or equal to 2 mm Hg and in seven eyes by greater than or equal to 4 mm Hg. In glaucoma patients, IOP in six eyes was increased by greater than or equal to 2 mm Hg and in two eyes by greater than or equal to 4 mm Hg. Conclusion: A tight necktie increases IOP in both normal subjects and glaucoma patients and could affect the diagnosis and management of glaucoma.