E-mail: angela.ehmer@med.uni-heidelberg.de

1. International Vision Correction Research Centre E-mail: angela.ehmer@med.uni-heidelberg.de Aspherical ablation profiles in excimer laser treatments • Ehmer, MSc, • M.P. Holzer, MD • G.U. Auffarth, MD The authors have no financial interests in any of the products mentioned. Dept. of Ophthalmology Ruprecht-Karls-University Heidelberg Chairman: H.E.Völcker, MD

2. Background – Aspheric profile of the cornea • the curvature of the cornea in the periphery is less compared to the apex  Shape of human cornea is no sphere • Human cornea is comparable to prolate ellipse • To specify the type of conicoid the parameter Q is used •  value for asphericity is Q Variation in conicoid for different asphericities Q, but for the same value of radius R (Source: Kiely et al., 1982) Q > 0  ellipsoid with the major axis in the X-Y plane Q = 0  sphere -1 < Q < 0 ellipsoid with the major axis in the Z direction Q = -1  paraboloid with the axis along the Z axis Q < -1  hyperboloid Angela Ehmer

3. Purpose and Methods • Purpose • Analysis of corneal shape following excimer laser treatment with an aspheric ablation profile • Methods • Preop • Visual acuity, refraction, pachymetry, corneal topography, wavefront analysis, pupillometry • Excimer laser treatment • Schwind ESIRIS; Wavefront optimized, aspheric • LASIK or LASEK • Postop 3, 6, 12 months • Visual acuity, refraction, wavefront analysis • Minimum pupil size 6mm

4. Results • LASEK 12 male (100%), 0 female • LASIK 20 male (41.67%), 28 female (58.33)

5. Comparison outcome: LASIK < 5 D vs. LASIK > 5 D Mean Q- value (Qm) for LASIK > 5 D Mean Q- value (Qm) for LASIK < 5 D • Mean Q value is calculated with Qflat and Qsteep of each eye Uncorrected post op visual acuity

6. Comparison outcome LASIK < 5 D vs. LASIK > 5 D Qm-Value and Spherical Aberrations * significant differences between the two groups (Wilcoxon, p< 0.05)

7. 2 2 1.5 1.5 1 1 0.5 0.5 0 0 -0.5 -0.5 Qm Pre Qm 3 Qm 6 Qm 12 Qm Pre Qm 3 Qm 6 Qm 12 -1 -1 -1.5 -1.5 Comparison of outcome LASEK vs. LASIK < 5 D Mean Q- value (Qm) for LASIK < 5 D Mean Q- value (Qm) for LASEK • Mean Q value is calculated with Qflat and Qsteep of each eye Uncorrected post op Visual acuity

8. Comparison of outcome LASEK vs. LASIK < 5 D µm LASIK < 5dpt LASEK 1.2 1 0.8 0.6 Qm Qm SA SA 0.4 * 0.2 * 0 post pre post pre post pre post pre -0.2 Qm-Value and Spherical Aberrations * significant differences between the two groups (Wilcoxon, p< 0.05)

9. Conclusions • LASIK < 5 D vs. LASIK >5 D • No statistical difference in visual acuity • No correlation between visual acuity and Q value • Good correlation between spherical aberrations • and Q- value • LASIK < 5 D vs. LASEK • No statistical difference in visual acuity • No correlation between visual acuity and Q- value • Good correlation between spherical aberrations • and Q- value

10. Conclusions • Q value is a geometric difference of the spherical and the aspherical shape • Q-value in all groups is positive even though visual acuity is 20/20 and better • Change of dioptres and Q-value – no change in spherical aberrations • Spherical aberrations seems to be a more ideal target instead of Q value

11. Certified for DIN EN ISO 9001:2000 G.U. Auffarth, MD, PhD A. F. M. Borkenstein, MD A. Ehmer, MSc S. Hara, MD M.P. Holzer, MD H. Jin, MD I.J. Limberger, MD T.M. Rabsilber, MD M.J. Sanchez,MD I. Schmack, MD Web: www.lasik-hd.de