Biomechanical properties of axially myopic cornea.

Purpose: To investigate biomechanical parameters of the cornea measured with ocular response analyzer (ORA) in myopic eyes with high axial length and the relationship between these parameters and axial length (AL).
Methods: A total of 165 eyes of 165 consecutive patients were included. Eyes with AL greater than 26 mm were named group 1 and eyes with AL shorter than 26 mm were named group 2. Axial length and keratometric values were measured by intraocular lens (IOL) Master optical biometry. Metrics of corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF), were measured with the ORA. The ORA also determined the values of intraocular pressure (IOPg) and corneal compensated IOP (IOPcc).
Results: The mean age of total subjects was 43.0 ± 15.6 years. Eighty-three eyes were included in group 1; 82 eyes were included in group 2. The CH and CRF of group 1 were significantly lower than group 2. The IOPcc was significantly higher in group 1 than group 2. When group 1 and group 2 were combined for analysis, CH was negatively correlated with age. Both CH and CRF were significantly correlated with SE. However, CH and CRF were negatively correlated with AL. Also, there was significant correlation between AL and IOPcc (p<0.05).
Conclusions: Highly myopic eyes showed decreased CH and CRF. As the AL increased the IOPcc also increased and the CH decreased. We conclude that the biomechanical properties of the cornea change with elongation of the eye and this may have an impact on IOP measurement.