Analysis of factors affecting corneal deflection amplitude in normal korean eyes

Purpose: To analyze the corneal deflection amplitude (DA), as measured by the Corvis ST tonometer (Oculus), and other ocular parameters that could affect the DA in normal Korean eyes. Methods: A retrospective study was performed on 126 eyes of 126 normal Korean subjects. Intraocular pressure (IOP) was measured with Goldmann tonometry (IOP-G), and the Corvis ST was used to measure the corneal DA, central corneal thickness (CCT) and IOP; the biomechanically corrected IOP-B was measured with non-contact tonometry (IOP-N). Axial length (AxL), anterior chamber depth (ACD), and the mean keratometric value were obtained with the IOL Master instrument (Zeiss). The relationships between DA and other measurements were then evaluated. Results: The DA was positively correlated with AxL (p = 0.002) and ACD (p = 0.010), and negatively correlated with IOP-G (p < 0.001), IOP-N (p < 0.001), IOP-B (p < 0.001), and CCT (p = 0.006). However, when AxL, ACD, CCT, and each type of IOP were analyzed together, AxL (p = 0.016) and IOP-G (p < 0.001) were the parameters most significantly associated with the DA. Conclusions: A longer AxL and greater ACD were associated with a higher DA, while a higher IOP and thicker CCT were associated with a lower DA. DA, one of the biochemical parameters of the cornea, was affected by multiple ocular factors, i.e., AxL and IOP. These factors should therefore be considered when interpreting DA measurements obtained using the Corvis ST.