The Effect of Corneal Thickness, Densitometry and Curvature on Intraocular Pressure Measurements Obtained by Applanation, Rebound and Dynamic Contour Tonometry

Abstract

Evaluate the effect of corneal thickness, densitometry and curvature on intraocular pressure (IOP) measurements obtained by Goldmann applanation tonometry (GAT), non-contact tonometry (NCT), rebound tonometry (RT), and dynamic contour tonometry (DCT). A cross-sectional prospective study involving 40 participants was performed. Corneal measurements were obtained using Pentacam (Oculus GMbH, Wetzlar, Germany), densitometry was measured at annuli of 0–2, 2–6, 6–10 and 10–12 mm. The relationship between corneal thickness (central, 4 and 6 mm), corneal astigmatism and corneal densitometry and IOP was examined. There was a significant relationship between corneal thickness (central, 4 and 6 mm) and GAT180, GAT90, RT, and NCT (P < 0.001 for all comparisons) but not for DCT. Higher corneal densitometry (6–10 mm and 10–12 mm zones) was associated with higher IOP from GAT180 and GAT90, and higher densitometry in the 6–10 mm zone correlated with higher IOP from NCT, however corneal densitometry increased with age. Accounting for age, the relationship between corneal densitometry and IOP measurements was not significant. In eyes with greater corneal astigmatism there was a greater difference between GAT90 and GAT180 measurements. IOP measurements may be affected by corneal thickness, densitometry and curvature. DCT was less affected by properties of the cornea compared to other devices.

Early influence of endotamponade on corneal biomechanical parameters, central corneal thickness and accuracy of intraocular pressure measurement

“…The question arises, whether the reduction was related to the surgery itself or it was a result of 6-months presence of intraocular silicon oil tamponade or both. Current studies suggest that in eyes with chronically elevated IOP, CCT is significantly reduced, what can be consistent with long-term increase in IOP related to silicon oil tamponade lasting 6-months in our patients 23 . The pathomechanism of CCT changes in patients with elevated IOP is not entirely clear 24 .…”

Intraocular Pressure and Its Relation to Ocular Geometry: Results From the Gutenberg Health Study

“…Ethnicity 6 , 20 , 24 , 43 and the measurement method to determine IOP 44 – 50 are known factors that influence IOP results: CCT does not seem to interfere with IOP measurements taken by Pascal dynamic contour tonometry. 47 Abah revealed a correlation between CCT and IOP using Perkins applanation tonometry, 5 whereas in the South African Eye Study this association was shown using rebound tonometry.…”

Effects of Corneal Biomechanical Properties on Rebound Tonometry (Icare200) and Applanation Tonometry (Perkins) Readings in Patients With Primary Congenital Glaucoma

“…This restricted recruitment explains the large age range which could interfere with results, although the variable age was included in our analysis. A further limitation of the present study was that we did not examine possible effects of potentially relevant factors, including axial length,19 corneal characteristics such as corneal curvature,9 corneal diameter9 and corneal densitometry20 or effects of glaucoma treatment,21,22 and surgeries23 on the differences in IOP observed with different instruments.…”