Effects of postural changes on measured intraocular pressure and repeatability of PT-100 tonometer and agreement with applanation and indentation tonometry
African Vision and Eye Health
This study aimed to determine the effect of change in head and neck position and body posture on the repeatability of intraocular pressure (IOP) measurements with PT-100 noncontact tonometer and compare with Goldmann, PT-100 and Schiøtz tonometer readings. Setting: Optometry clinic, Saudi Arabia. Methods: The IOP was measured in one selected eye of 84 healthy participants (mean aged 21.9 ± 2.0 years) using PT-100 in three head and body positions, Goldmann tonometer and Schiøtz on two separate
... sits, in a randomised fashion. Central corneal thickness (CCT) was measured using an ultrasound pachymeter. The repeatability, agreement and correlations between CCT and IOP differentials were assessed. Results: The IOP measured in three head and body positions with the PT-100 were similar and comparable to Goldmann IOPs in sessions one and two with 74% and 86% of PT-100 measurements within ±3 mmHg of the Goldmann tonometry, respectively, for sessions one and two. The Schiøtz tonometer-measured IOP was higher than the Goldmann IOPs (p < 0.05) with 60% and 44% of Schiøtz IOPs within ±3 mmHg of the Goldmann tonometer IOP in sessions one and two, respectively. The limits of repeatability and reproducibility were best with the PT-100 and worst with the Schiøtz tonometer. The mean CCT (552±36 µm) was negatively correlated with differences between Goldmann and both PT-100 and Schiøtz-measured IOP. Conclusion: Postural changes did not affect the validity and repeatability of PT-100 readings. PT-100 measurements were interchangeable with Goldmann tonometer. Schiøtz overestimated Goldmann IOP in thicker corneas more than the PT-100.