Investigation And Analysis Of Q Value Of Corneal Anterior Surface In Jiangxi Myopia Population For Laser Refractive Surgery

Objective:To assess the distribution features of Q-value of corneal anterior surface in jiangxi myopia population for laser refractive surgery and to investigate the relationship between Q-value and other related parameters, such as spherical equivalent (SE), corneal curvature, cornea astigmatism, wavefront data and age.Methods:The K&Q calculator of Orbscan-II anterior segment system was used to obtain the Q-value of 6 mm optical zone in 411 cases (822 eyes) .There were 188 male subjects (376 eyes) and 223 female subjects (446 eyes). According to SE, subjects were divided into three groups including low myopia, moderate myopia and high myopia. According to different age, subjects were divided into three groups including I group (age from 17 to 25), II group (age from 26 to 34) and III group (age from 35 to 44). Statistical analysis was used to comprehend the distribution characters of Q-value and its relations with SE, corneal curvature, cornea astigmatism, wavefront data and age.Results:The Q-value of 822 eyes (411 cases) distributed as positive normal distribution, the average of Q- value was -0.148±0.120 (range frome -0.73 to 0.56) and -0.130±0.128 for male subjects and -0.163±0.110 for female ones with statistically significant difference in Q-value in different genders(t=4.069, P=0.000). A significant difference was oberserved in Q-value among 17～25 years, 26～34 years and 35～44 years groups(F=4.567, P=0.011)as well as between 26～34 years group and 35～44 years group(P=0.004). However, there was no significant difference was found between different myopic groups(F=1.434,P=0.239). the Q-value shown significantly negative relationship with C12, the Q-value show poor relationship with cornea curvature, cornea astigmatism, RMSh and C8. But the Q-value was not related with SE, RMSg, C7, cornea thickness, ocular pressure and age.Conclusions:In jiangxi myopia population for refractive surgery corneal curvature of majority population become flatter from center to periphery (Q<0), minority become steeper from center to periphery (Q>0). The Q-value of corneal anterior surface is independent from myopic SE. The Q-value show poor relationship with cornea curvature, cornea astigmatism, RMSh and C8. C12 was the most important related factor of Q-value. The Q-value was significantly greater in males than in females. A significant difference was oberserved in Q-value between 26～34 years and 35～44 years group.