Association between corneal biomechanical properties and myopia in Chinese subjects

Purpose To examine the relationship between corneal biomechanical properties and the degree of myopia. Methods Chinese subjects (n = 172, age: 11-65 years) were divided into diagnostic groups with non-myopia (spherical equivalence (SE) > 4 -0.50 D), low (-3.00 <= SEr <= -0.50 D), moderate (-6.00 <= SE< -3.00 D), and high myopia (SE< -6.00 D). Only the right eye of each subject was analyzed. Central corneal thickness (CCT) was measured by optical coherence tomography. An ocular response analyzer was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), intraocular pressure (IOP), and corneal compensated IOP (IOPcc). Refraction was measured by both automated and subjective refractometry and expressed as SE. Results CH was significantly lower in high myopia compared with both low and non-myopia (P <= 0.002). CCT was 1.5 times more correlated to CH variation compared with refraction. Similarly, CRF was four times more dependent on CCT than refraction. CH (P<0.001) or CRF (P=0.005) was positively correlated to refraction. Both IOP and IOPcc were negatively correlated to refraction (P<0.001), respectively. Conclusions CH decreases only in high myopia. Refraction is positively correlated to both CH and CRF but negatively correlated to both IOP and IOPcc. These results indicate that the mechanical strength in anterior segment of the eye is compromised in high myopia. In addition, high myopia may increase the risk of glaucoma. Eye (2011) 25, 1083-1089; doi:10.1038/eye.2011.104; published online 6 May 2011