Influence of Corneal Thickness Changes during Active Uveitis on Goldmann Applanation and Dynamic Contour Tonometry

Abstract

Background: To compare the influence of central corneal thickness (CCT) during active anterior uveitis and after resolution on intraocular pressure (IOP) measurements by Goldmann applanation tonometry (GAT) and by dynamic contour tonometry (DCT). Design: Prospective, single-center study including 30 consecutive patients with active unilateral uveitis. Main Outcome Measure: CCT influence on GAT and DCT in active uveitis. Results: Average age of included patients (total n = 30; 16 women) was 46.5 years (range: 22.3–75.4). During activity, the cornea was thicker than on the unaffected side (645 vs. 585 µm, p = 0.0001). At the follow-up visit (inactive time point), the corneal thickness of the affected eye fell to a CCT of 581 µm (p < 0.0001). IOP measured by DCT was always higher than that measured by GAT. IOP was significantly lower during the active phase (GAT = 14.3 ± 5.8 mm Hg, DCT = 16.3 ± 5.9 mm Hg) than when disease was inactive (GAT = 17 ± 6.2 mm Hg, p = 0.016; DCT = 19.6 ± 6.9 mm Hg, p = 0.0006). The two techniques showed a high concordance, with a correlation coefficient of 0.76 (p < 0.001) in the affected eye at the active time point and when inactive 0.95 (p < 0.001). In addition, no systematic difference between these two techniques was observed according to the Bland-Altman method of comparison. No correlation between ΔIOP (GAT – DCT) and CCT could be detected at either time point. Conclusions: CCT increases during active phases of anterior uveitis. The edematous corneas lead to an additional decrease in IOP measurements by GAT and DCT. Both techniques were in good concordance in the patients, and the difference between GAT and DCT IOP readings was not influenced by CCT.