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Higher order aberrations with aspheric ablations using the Nidek EC-5000 CX II laser
Ian Y L Yeung1, Sanjay Mantry, Ian A Cunliffe
1Midland Eye Institute, West Midlands, United Kingdom.
Journal of Refractive Surgery (Thorofare, N.J. : 1995)
|November 4, 2004
Summary
Laser vision correction using an aspheric ablation profile increased higher order aberrations in myopic eyes. Postoperative changes were deemed acceptable, though their clinical significance requires further investigation.
Area of Science:
- Ophthalmology
- Refractive Surgery
- Optometry
Background:
- Laser in situ keratomileusis (LASIK) is a common refractive surgery.
- Higher order aberrations (HOAs) can affect visual quality after LASIK.
- Aspheric ablation profiles aim to minimize HOAs compared to older spherical profiles.
Purpose of the Study:
- To analyze changes in higher order aberrations (HOAs) after LASIK.
- To evaluate the impact of an aspheric ablation profile on HOAs in myopic and myopic astigmatic eyes.
- To assess visual outcomes using the Nidek EC-5000 CX II excimer laser system.
Main Methods:
- Retrospective audit of 38 eyes from 19 patients with myopia/myopic astigmatism.
- Utilized a customized aspheric transition zone profile (CATz) with a 5 mm ablation zone and 9 mm transition zone.
- Employed FinalFit software and the Nidek EC-5000 CX II excimer laser system for the procedure.
Main Results:
- Mean HOAs (RMS) increased from 0.42 µm preoperatively to 0.57 µm at 6 months post-surgery.
- Mean spherical aberration (Z12) increased significantly from 0.02 µm to 0.33 µm.
- Spherical aberration defocus equivalent (DEQ) rose from 0.56 µm to 1.54 µm at 6 months.
Conclusions:
- The increase in postoperative HOAs following aspheric LASIK was within acceptable limits.
- The clinical significance of the observed numerical changes in aberrations remains undetermined.
- Further research is needed to understand the long-term visual impact of these HOA changes.