Change in K Values in Corneal Zones After Myopic LASIK
Purpose
To know exactly what and how much changes are taking places across cornea following LASIK in myopic eyes.
Methods
One-hundred sixty-two eyes of 81 patients, who underwent LASIK for myopia up to -10.0D, were evaluated by modern corneal topographer pre and 2 months post op. All cases were grouped into 3. Group A up to -3D; Group B >-3 to -5D; while Group C >-5 to -10D. All eyes were treated by Excimer Laser after creating flap of either 90 µm or 130µm with the help of microkeratome. All data related to K values in different zones of cornea i.e. between 0 to 3mm, 3mm to 6mm and 6mm to 9mm were recorded according to the group.
Results
Central cornea (not Sim values) became flat by 3.66%, mid peripheral by 3.57% and peripheral by 0.09% in group A. In group B, central cornea became flat by 7.90%, mid peripheral by 5.85%, while peripheral by 0.02% in group C, central cornea became flat by 13.57%, mid peripheral by 8.28%, while peripheral by 2.02%. It was observed that changes in K values in central (0 to 3mm) zone and mid peripheral (3mm to 6mm) zone were different (treated area was 6mm). There was flattening beyond treatment zone which gives prolacity of cornea.
Conclusion
One-hundred sixty-two myopic eyes of 81 patients were treated with Lasik. Changes in K values pre and post were studied in 3 different zones of cornea. Maximum flattening was found in central zone and some flattening in non-treated peripheral zone which gives prolacity to the cornea.