| BackgroundAt present, corneal refractive surgery has made rapid development and become the most popular and fastest growing disciplines, and its treatment with high security and good predictive and rapid recovery of visual acuity. However, the postoperative uncorrected visual acuity in some patients, even at 1.0 or 1.0 above, still blurred-vision, glare, halo and night vision loss and other complications. As the introduction of the corneal asphericity, clinicians increasingly aware of these issues link with the changes of corneal asphericity and Q-value Adjusted customized ablation treatment come into being. In the ophthalmology field, asphericity is used to describe the anterior corneal surface shape, is an important parameter. Usually expressed in the Q value.It is widely used in the diagnosis of corneal shape abnormalities of eye; evaluation of corneal shape changes before and after surgery in corneal refractive surgery in particular corneal laser refractive surgery, as well as the Q-value Adjusted customized ablation treatment. Q-value Adjusted customized ablation treatment has just come into clinical, the relevant research work has just begun. This study, a random collection of 300 cases of myopia patients (600 eyes) with Q-value of 6mm and the RMS of wavefront aberrations, to explore distribution of Q values in the myopic refractive surgery population, and study with the relativity of other parameters such as refraction, sex, age, corneal curvature, corneal thickness and the RMS of whole wavefront aberrations, higher-order aberrations,spherical aberration, Provide the basis for the identification Q-value and application in corneal laser refractive surgery.ObjectiveTo study the distribution characters of corneal asphericity (Q-value) in myopia population and the related influencing factors.MethodsSix hundred eyes of 300 patients with myopia for corneal laser refractive surgery in Refractive Surgery Center of the First Affliated Hospital of Zhengzhou University were enrolled in this study with each Patient selected randomly. The K&Q calculator of OrbscanⅡz anterior segment system was used to obtain the Q-value of 6 mm optical zone in 300 cases (600 eyes), and Zywave aberrometer was used to obtain the RMS of whole wavefront aberrations, higher-order aberrations,spherical aberration at the 6 mm pupil sizes. Statistical analysis was used to comprehend the distribution characters of Q-value and its relations with diopter, cornea curvature cornea diameter, the RMS of whole wavefront aberrations, higher-order aberrations,spherical aberration and so on.The data were analyzed with statistical software SPSS17.0.Numerical data were expressed with x±s.The statistical methods included Person correlation and one-way ANOVA. Results were considered significant at P<0.05. Results1. The Q-value of 600 eyes ranged from -0.51-0.37 with the mean value-0.17±0.11. The Q-value of low and moderate myopic group 351 eyes with the mean value -0.16±0.11, The Q-value of high myopic group 249 eyes with the mean value -0.18±0.12, there was no significant statistics difference between the two groups.2. The RMS of whole wavefront aberrations at the 6mm pupil sizes with the mean value (9.25±2.63) um,higher-order aberrations (0.43±0.16)um, spherical aberration (0.06±0.05)um.The Q-value show no correlation with the RMS of whole wavefront aberrations, higher-order aberrations, but show a positive correlation with spherical aberration.3. The Q-value show a negative correlation with cornea curvature, simulated keratometry, irregular index of 3mmzone, irregular index of 5mm zone, diff value of anterior surface; the Q-value show and a positive correlation with anterior chamber depth and cornea diameter; the Q-value show no relates with spherical diopter,spherical equivalent,astigmatism diopter,diff value of posterior surface, age, intraocular pressure,cornea thickness.4. The Q-value of men with the mean value -0.15±0.11 and women -0.18±0.11. There was significant statistics differences between men and women of the Q-value.5. The Q-value of left eyes with the mean value 0.17±0.06 and right eyes -0.16±0.12.There was no significant statistics difference between right and left eyes of the Q-value.Conclusions1. The Q-value of 600 eyes were normal distribution, ranged from -0.51-0.37 with the mean value -0.17±0.11. there was no difference between the low, moderate myopic group and high myopic group.2. The Q value was related with many factors. Especially show a significant negative correlation with cornea curvature and a positive correlation with spherical aberration.
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