Abstract
Abstract: :
Purpose: Assessment of 4 topography systems: C-Scan (MedRx Technologies, USA), Eye-Top (CSO, Italy), Tomey TMS-2N (Tomey, Japan) and Keratron Scout (Optikon, Italy) with regard to suitability for customized ablation. Methods: Corneal maps were obtained from normal eyes and eyes after refractive surgery for hyperopia, myopia and astigmatism correction including eyes with central islands (CI) and decentered ablations. Maps were obtained also from eyes with corneal pathologies, such as keratokonus, penetrating keratoplasty, and corneal scars. Measurements were evaluated with regard to reproducibility, resolution and pupil detection. The results are demonstrated for normal eyes and eyes with CI after myopic PRK. Results: Reproducibility was ±0.4 D for the C-Scan, ±1.0D for Eye-Top and TMS 2N and ±4.0D for the Keratron Scout. Reproducibility of the Elevation Map was ±1 µm for the C-Scan, ±4 µm for Eye-Top and TMS 2N and ±12 µm for the Keratron Scout. Image Resolution was very high for the C-Scan and high for Eye-Top, TMS 2N and Keratron Scout. Pupil detection was mediocre for all systems but Keratron Scout, which showed only poor pupil detection abilities. Conclusion: Customized ablation needs topography devices with high resolution AND high reproducibility. Furthermore of importance is an accurate elevation map and a reproducible reference point for the topography. The best combination of these criteria’s was found for the C-Scan. Eye-Top and TMS-2N showed acceptable reproducibility. The Eye-Top did not display small corneal irregularities. The TMS-2N was unable to measure surfaces with higher irregularities. Keratron Scout showed a reproducibility in principle not acceptable for customized ablation.
Keywords: 547 refractive surgery: corneal topography • 544 refractive surgery • 534 pupil