Comparative analysis of biomechanically corrected intraocular pressure with corneal visualization Scheimpflug technology versus conventional noncontact intraocular pressure.

PURPOSE

To compare the difference between biomechanically corrected intraocular pressure (bIOP) and noncontact IOP measurement (IOP) and to investigate the effect of corneal biomechanical properties on IOP.

METHODS

IOP was evaluated in 1046 myopic eyes (544 subjects) using a conventional noncontact tonometer and a novel corneal visualization Scheimpflug technology (Corvis ST). Corneal biomechanical parameters were measured using the Corvis ST.

RESULTS

The mean IOP and bIOP values were significantly different (15.59 ± 2.56 mmHg and 15.89 ± 1.75 mmHg, respectively; P < 0.001). The bIOP showed a less correlation with central corneal thickness (CCT), compared with IOP (P < 0.01). The IOP was lower than the bIOP when the thickness of cornea was ≤ 550 μm but higher than bIOP when it was ≥ 550 μm (P < 0.01). A strong association was found between IOP and deflection amplitude and deflection area at the highest concavity (HC DefA and HC DefArea), stiff parameter, maximum deformation amplitude (DAmax), and maximum deflection amplitude (DefAmax), as well as for bIOP (r > 0.500, P < 0.001). The bIOP could be calculated based on IOP according to different values of CCT (P < 0.01).

CONCLUSIONS

The bIOP was less affected by CCT as compared to IOP. IOP may be underestimated when the cornea is thinner and overestimated when the cornea is thicker because of the difference in corneal biomechanics.