Patients who are candidates for LASIK may be have one of these vision issues. They could be nearsighted (Myopia), farsighted (Hyperopia) and/or have an an irregular curvature of their eye (Astigmatism).
With normal vision, images focus properly on the retina.
1. Myopia: or nearsightedness
The eye is too long. Images focus in front of the retina. With a myopic patient, the surgeon uses the laser treatment to make the eye shorter, so that images focus clearly on the retina.
2. Hyperopia or Farsightedness
The eye is too short. Images focus behind the retina. With a hyperopic patient, the surgeon uses the laser treatment to reshape the cornea, so the eye is longer, so that images focus properly on the retina.
Any of these conditions can have an additional visual issue, astigmatism.
With Astigmatism, the cornea is shaped like a football, instead of like a basketball. Images focus on multiple spots on the retina, causing blurred vision. With an astigmatic patient, the surgeon uses the laser treatment to reshape the cornea so that images focus precisely in one spot on the retina for clear vision.