Abstract
Purpose :
To assess the relationship between biomechanical metrics and Intraocular Pressure (IOP) and determine whether the Corneal Biomechanical Index (CBI) is directly influenced by IOP.
Methods :
Retrospective analysis of 511 eyes from 256 healthy patients who were screened for refractive surgery and fulfilled the safety criteria. We obtained biomechanical properties recordings using the Corvis ST tonometer. We computed IOP, CCT, deformation amplitude (DA), 1st applanation time (A1 time), 1st applanation velocity (A1 velocity), 2nd applanation time (A2 time), 2nd applanation velocity (A2 velocity), highest concavity time (HC time), peak distance (PD), highest concavity radius (HC radius), A1 deflection length, A2 deflection length, and CBI . Correlation coefficients between the sample variables were calculated with Pearson test. Multivariable regression models were used to establish the relationship between CBI and IOP with the rest of the variables.
Results :
Patient mean age was 28.07 ± 5.41 years and 69.86% of the eyes belonged to female patients. A statistically significant correlation was found between IOP and eight of the CST parameters. The strongest association was found to be between IOP and DA, PD and A2 time in descending order. The association between CBI and the all the variables studied showed a low association. The first multivariable regression model constructed disclosed that the IOP variable can predict CBI with a very low precision. The second model showed that DA, HC radius, A1 deflection length, PD, A1 velocity and A2 time can predict IOP with more than 87.08% accuracy, with an error of ±1.45 mmHg.
Conclusions :
A higher IOP leads to a lower deformation and the cornea rebounds sooner, leading to a shorter A2 time. Even though most CST parameters showed a strong association with IOP, none of the parameters revealed a strong correlation with CBI meaning they do not modify its variance. In conclusion, despite the fact that IOP is the strongest predictor for the cornea’s deformation amplitude, IOP changes do not influence CBIs effectiveness in detecting subclinical keratoconus. We introduce a new method for estimating IOP. A formula was created to predict IOP with the variables of the model. This method can aid when anomalies that affect pressure readings are present.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.