摘要
目的用调制传递函数（MTF）客观分析正常人眼全角膜的光学特性。方法横断面研究。选取200例（400眼），年龄为18-40岁拟做准分子激光手术的患者（柱镜度在-1．00以内），应用Sirius角膜地形图分析仪，经Phoenis分析软件模拟得出3、4、5、6、7mm角膜光学区域，校正角膜低阶像差后，在全角膜的垂直和水平子午线的MTF曲线上，选取5、10、15、20、25、30、35、40、45、50、55和60c／d空间频率的MTF值进行统计学描述．左右眼之间MTF值及斯特列尔比（SR）的比较采用配对t检验或符号秩和检验。结果MTF曲线在各角膜光学区域从低频至中频（5-15c／d）迅速下降，高频（〉15c／d）趋向缓和至零。随角膜光学区域的增大，MTF曲线逐渐降低。在3-6mm角膜光学区域时左右眼的SR值差异无统计学意义，呈镜像对称。7mm时右眼的SR值较左眼高，且差异有统计学意义忙-2．220，P=0．028）。3-5mm角膜光学区域时，水平子午线各空间频率的MTF值均大于垂直子午线的MTF值，差异有统计学意义。6-7mm在空间频率为20、25、30、35、40、45c／d时，水平子午线的MTF值小于垂直子午线，但差异无统计学意义。结论MTF能较客观、相对准确地对角膜成像质量进行评估描述。
Objective To use the modulation transfer function （MTF） to objectively analyze the optical quality of normal human cornea. Methods In this cross-sectional study, 200 patients （400 eyes） between18 and 40 years of age （cylindrical refraction less than -1.00 D） were enrolled. A Sirius corneal analyzer was used to measure the optical quality of the complete cornea. Different optical diameters, 3.0, 4.0, 5.0, 6.0 mm, and 7.0 mm, were analyzed for MTF and sterhl ratio （SR） values with Phoenix analysis software at different spatial frequencies （5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 c/d）. A comparison of MTF values at the same spatial frequencies at vertical and horizontal meridians and SR values were analyzed with a paired t test or signed rank test. Results ①The MTF curve decreased rapidly from low to intermediate frequencies （5-15 c/d）, then eased to zero at high frequencies （〉15 c/d）. ②The MTF value decreased as the optical diameter increased. ③There was no significant difference in SR values between the right and left eyes in 3-6 mm optical diameters, showing a mirror symmetry. With a 7 mm optical diameter, the SR value of the right eye was significantly higher than that of the left eye （t=2.220, P=0.028）. ④In 3-5 mm optical diameters, the MTF value of the horizontal meridian was higher than that of the vertical meridian, while in 6-7 mm diameters there was no significant difference in the MTF value between the vertical and horizontal meridians at most spatial frequencies （20, 25, 30, 35, 40, 45 c/d） though the MTF value of horizontal less than vertical. Conclusion The modulation transfer function can objectively evaluate and describe the image quality of the cornea that is relatively correct.
出处
《中华眼视光学与视觉科学杂志》
CAS
2012年第3期157-160,共4页
Chinese Journal Of Optometry Ophthalmology And Visual Science
关键词
调制传递函数
光学质量
角膜
斯特列尔比
Modulation transfer function
Optical quality
Cornea
Sterhl ratio
