步骤一：用角膜曲率仪测量角膜曲率，两个方向各测三次，取平均值，得到角膜曲率的平均K值，选取与K值接近的镜片作为试戴片。
Keratometer was used to check the corneal curve at 2 direction for 3 times to offer the mean K value , and a nearest basal lens to K value was selected as the trial lens .
角膜曲率仪