Abstract
Purpose :
Decorrelation-based OCT is of interest for cornea biomechanics because it can provide spatially-resolved mechanical contrast based on the microstructural dynamics of the corneal tissue in a wholly non-perturbing manner. Previously, it was found that there was no significant relationship between intraocular pressure (IOP) within normal limits and decorrelation coefficient of the cornea averaged in depth. However, it was suspected that there may be a depth-dependent effect wherein the anterior half of the cornea experiences negative strain and the posterior half of the cornea experiences positive strain, and exhibits, respectively, a relative increase and decrease in decorrelation coefficient.
Methods :
Whole porcine globes, obtained fresh from the abattoir, were used in this study with externally-controlled intraocular pressure. IOP was varied from 15 to 25 mmHg while the corneas were imaged with a spectral domain OCT system with a central wavelength of 1310nm. Scans were acquired using an M-B scan pattern with 2ms M-scans. Decorrelation coefficients were calculated using custom MATLAB software, pixelwise with a maximum of 0.06ms of lag.
Results :
It was found that there was a depth-dependent change in decorrelation coefficient as a function of IOP. (Figure 1). It is hypothesized that the change in decorrelation coefficient is due to changing internal stresses in the cornea as a result of IOP. This corresponds well with recently published literature regarding the distribution of strain within the cornea with increasing IOP.
Conclusions :
As decorrelation-based OCT is used to study the depth-dependent mechanical properties of the cornea, for instance, in disease detection and treatment monitoring, the possible depth-dependent effect of IOP should be considered.
This is a 2021 ARVO Annual Meeting abstract.