A patient had a −10 D myopic LASIK treatment years ago. Now, she presents for cataract surgery.
Which change introduces the most error in the lens calculations compared to her eye if it had never had LASIK?
1.Corneal curvature measurements
2.High-order aberrations
3.Axial length
4.Anteroir chamber depth
explanation
LASIK achieves a change in the prescription by the microscopic removal of corneal tissue and reshaping the anterior contour of the cornea. The amount of tissue removed is in the order of 100 µm (0.01 mm). The amount of change in axial length is small compared to the changes in keratometry. Depending on the location of corneal curvature measured, there can be large variations in values, with the central cornea being much flatter. This introduces the most error in the lens calculations.