Material and Method: In this prospective randomized- controlled study 42 eyes of 24 patients with spheric equivalent (SE)≥-6.00 Diopters (D) were included in the study group and 43 eyes of 27 age-sex matched patients with +0.50≤SE≤-2.50D were included in the control group (group 1). The study group was divided into two groups according to the refractive power (-6.00≤SE≤-12.00D group 2, SE>-12.00D group 3). Biomechanic properties of cornea (corneal hysteresis [CH], corneal resistance factor [CRF], Goldmann- correlated pressure [IOPg], corneal-compensated pressure [IOPcc]), axial length (AL) and central corneal thickness (CCT) were compared between groups.

Results: AL, CH, CRF, IOPcc and CCT were different in multiple group analysis (p<0.001), IOPg was similar (p=0.321). CH and CRF values were lower in high myopia groups (CHp1-2 =0.004, p1-3<0.001; CRFp1-2=0.012, p1-3<0.001). IOPcc was higher in high myopia groups (p1-2=0.049, p1-3<0.001). Between group 1-3, CCT was statistically different (p=0.002) whereas there were no difference between group 1-2, and between group 2-3 (p1-2=0.106, p2-3=0.719). While there was a strong relation between SE and CH, CRF, IOPcc and AL (r=-0.554 p<0.001; r=-0.428 p<0.001; r=0.402 p<0.001; r=0.916 p<0.001, respectively) there was a moderate relation with CCT.

Discussion: According to this study CH and CRF values decrease while SE and AL increase. While there is a strong positive relation between IOPcc with AL and SE no relation was with IOPg. So it may be assumed that measuring intraocular pressure (IOP) lower than normal may probably be a result of decrease in corneal biomechanical power. In high myopic patients IOP measurement techniques which take corneal biomechanic properties into consideration should be used. Keywords : Axial length, corneal biomechanical properties, ocular response analyzer, high myopia