To compare the intraocular pressure (IOP) measured using the rebound tonometer (RT) and Goldmann applanation tonometer (GAT) in the primary position and upgaze in restrictive thyroid eye disease (TED).

We measured the IOP in 30 subjects (54 eyes) who visited an ophthalmologist between May 2014 and May 2015. This study included 16 healthy volunteers (32 eyes) and 14 TED patients (22 eyes). The outcome measurements were the comparison of IOP readings; both intergroup and 2 measurements using the RT and the GAT for patients with restrictive TED and the control group. Upgaze IOP was measured on the central cornea with a 20-degree chin-down posture.

Both TED patients and controls showed an increase in IOP in upgaze compared with primary position ( p < 0.001). There was a significant difference in mean differential IOP between patients and controls measured using RT and GAT, respectively ( p < 0.001). In the control group, there was no significant difference between the 2 instrument readings in upgaze as well as primary position for patients with restrictive TED ( p = 0.853 in TED; p = 0.260 in controls).

Based on our results, the mean IOP in conventional upgaze was significantly increased in TED patients compared to primary position using both the RT and GAT and no difference in RT readings compared with GAT readings. The RT can be used to establish IOP since no significant difference between the upgaze and the primary position readings was observed in patients with restrictive TED and is a simple and effective diagnostic tool unrelated to the position and the direction of gaze.