1. cgarce@terracom.br Financial Disclosure: Medical Director–Galilei R&D Consultant, Ziemer Group AG, Port, Switzerland Consultant & Territory Manager for Latin America, Vista Optics Limited, Widnes, UK Consultant, Mark’Ennovy Personalized Care, Madrid, Spain Author does not have financial interest in the commercialization of equipments or IOLs mentioned Carlos G. Arce, MD Carlos G. Arce, MD Ophthalmologist, Private Eye Clinic, Campinas, SP, Brazil Volunteer Ophthalmologist and Researcher, Ocular Bioengineer and Refractive Surgery Sectors, Institute of Vision, Department of Ophthalmology, Paulista School of Medicine, Federal University of São Paulo, SP, Brazil Spherical Aberration and Eccentricity Factor of Normal Corneas and Corneas That Had Underwent Refractive Surgery

2. Results: Normal corneas had SA=+0.24 ±0.07 µm (-0.18 ±0.08 D), anterior Є 2 =+0.20 ±0.16 and posterior Є 2 =+0.25 ±0.16. Corneas that underwent myopic LASIK had SA =+0.67 ±0.19 µm (-0.50 ±0.14 D) (P<0.005); anterior Є 2 = -1.01 ±0.33 (P<0.0005), and posterior Є 2 =+0.39 ±0.18 (P<0.05). Corneas with hyperopic LASIK had SA -0.66 ±0.13 µm (0.40 ±0.11 D) (P<0.005); anterior Є 2 = +1.54 ±0.22 (P<0.0005) and posterior Є 2 =+0.41 ±0.13 (P<0.05), Purpose: To study the spherical aberration (SA) and shape profile of normal corneas and that underwent myopic or hyperopic corneal LASIK. Setting: Private Eye Clinic, Campinas, SP, Brazil Methods: Total corneal SA and eccentricity (Є 2 ) index were assessed with the Galilei (Ziemer Ophthalmic Systems AG, Port, Switzerland) dual Scheimpflug- Placido integrated system were assessed in 39 normal corneas (24 patients) that underwent myopic or hyperopic LASIK. Preoperative spherical equivalent range was -1.75 to -8.25 D in 29 eyes/19 patients, and +2.0 to +5.25 D in 10 eyes/5 patients, respectively. Myopic LASIK Spherical Aberration Anterior Є 2 Posterior Є 2 Spherical Aberration Anterior Є 2 Posterior Є 2 Hyperopic LASIK

3. Normal Cornea Without Refractive Surgery SA = 0.28 μm SA = -0.22 D Normal corneal surface is from sphere (Є 2 =0) to elliptical prolate (0<Є 2 <1) Total corneal SA is positive (µm) or negative (D): SA=+0.24 ±0.07 µm (-0.18 ±0.08 D) Final total eye SA depends on SA of IOL chosen. Target Rx for IOL calculation may be plano or little negative Example: Є 2 = 0.10

4. Anterior surface becomes oblate with negative Є 2 Total corneal SA is high positive (µm) or negative (D): SA=+0.67 ±0.19 µm (-0.50 ±0.14 D) IOL implanted should not be spherical with positive SA (µm) Target Rx may be plano or negative. Monovision is better accepted Cornea with Post-Myopic Refractive Surgery SA = 0.94 μm SA = -0.72 D Example: Є 2 = -1.44

5. Cornea with Post-Hyperopic Refractive Surgery Anterior surface becomes hyper-prolate with high positive Є 2 Total corneal SA becomes more negative (µm) or positive (D): SA= -0.66 ±0.13 µm (0.40 ±0.11 D) IOL implanted should not be aspheric hyper-prolate with negative SA (µm) Target Rx may be plano or little positive. Traditional monovision is less tolerated SA = -0.81 μm SA = 0.62 D Example: Є 2 = 1.83

6. Galilei measures the total corneal wave front Spherical aberration (SA) is linked to contrast sensitivity SA=0 gives sharpness of vision Larger SA gives depth of focus (multifocal cornea) Reasoning for Custom Selection of IOL When the cornea becomes more prolate When the cornea becomes more prolate Q factor and Є 2 increase Q factor and Є 2 increase Positive SA reduces Positive SA reduces Around Є 2 = 0.55 then SA = 0 Around Є 2 = 0.55 then SA = 0 Є 2 > 0.60 then SA is already negative Є 2 > 0.60 then SA is already negative When cornea becomes less prolate or oblate When cornea becomes less prolate or oblate Q factor and Є 2 reduce Q factor and Є 2 reduce Positive SA increases Positive SA increases

7. IOL SA + Total Corneal SA = Total eye SA after cataract extraction SphericalAberration V. & H. Coma H. Trefoil H. Quatrefoil V. Trefoil V. Quatrefoil Glasser & Campbell. Vision Res, 1998: 38 (2); 209 Artal et al. J. Opt. Soc. Am. A. Feb 2002 Total SA of the eye increases with Total SA of the eye increases with age due to lens changes age due to lens changes Total corneal SA maintains a stable Total corneal SA maintains a stable value with age in normal corneas value with age in normal corneas that do not change shape that do not change shape Total corneal SA becomes less positive or negative in typical Total corneal SA becomes less positive or negative in typical keratoconus keratoconus Total corneal SA becomes some Total corneal SA becomes some more positive in typical initial pellucid more positive in typical initial pellucid marginal degeneration marginal degeneration Total corneal SA after myopic Total corneal SA after myopic refractive surgery is more positive refractive surgery is more positive Flatter and more oblate corneas Flatter and more oblate corneas seem to have larger positive SA seem to have larger positive SA value value Total corneal SA after hyperopic refractive surgery is more negative Total corneal SA after hyperopic refractive surgery is more negative Steeper and more prolate corneas Steeper and more prolate corneas seem to have larger negative SA seem to have larger negative SA value value

8. Conclusions Conclusions SA and eccentricity factor Є 2 have an inverse SA and eccentricity factor Є 2 have an inverse correlation correlation Normal corneas and those that underwent refractive Normal corneas and those that underwent refractive surgery have not the same SA surgery have not the same SA Our results suggest that rational IOL selection and the Our results suggest that rational IOL selection and the target refraction expected in IOL calculation may be target refraction expected in IOL calculation may be optimized with preoperative data from total corneal optimized with preoperative data from total corneal wavefront derived by dual Scheimpflug –Placido wavefront derived by dual Scheimpflug –Placido tomographic system tomographic system Spherical IOLs with positive SA seem a good option for Spherical IOLs with positive SA seem a good option for eyes that underwent hyperopic refractive surgery or eyes that underwent hyperopic refractive surgery or with typical keratoconus. Aspheric IOLs with negative with typical keratoconus. Aspheric IOLs with negative SA seem a worst option SA seem a worst option In these eyes a plano or little positive target would be In these eyes a plano or little positive target would be ideal and classic monovision would not be recommended ideal and classic monovision would not be recommended Aspheric IOLs with negative SA seem a good option for Aspheric IOLs with negative SA seem a good option for eyes with normal corneas and that underwent myopic eyes with normal corneas and that underwent myopic surgery surgery Spherical IOLs are also an option in normal corneas Spherical IOLs are also an option in normal corneas when a small negative refractive target is expected when a small negative refractive target is expected Eyes that underwent myopic LASIK seem to be ideal for Eyes that underwent myopic LASIK seem to be ideal for classic monovision with myopic residual refraction classic monovision with myopic residual refraction Standard Sph (SA = +0.18 μm)Standard Sph (SA = +0.18 μm) PhysIOL (SA = -0.11 μm)PhysIOL (SA = -0.11 μm) AcrySof IQ (SA = -0.20 μm)AcrySof IQ (SA = -0.20 μm) Tecnis (SA = -0.27 μm)Tecnis (SA = -0.27 μm) SofPort AO (SA = 0 μm)SofPort AO (SA = 0 μm) Crystalens (SA =0 μm)Crystalens (SA =0 μm) Rayner (SA = 0 μm)Rayner (SA = 0 μm) Mediphacos (SA= 0)Mediphacos (SA= 0) central rays focus beyond outer rays central rays focus in front of outer rays All rays are focused at focused at same point Modified from Koch et al 2009