1. Analysis of Ocular Wavefront Aberrations in Post Penetrating Keratoplasty Eyes with Two Different Hartmann-Shack Aberrometers Adriana S. Forseto 1, MD; Telma Pereira 2, MD; Vera Mascaro 2, MD; Lucila Pinto 1, MD; Walton Nosé 1,2, MD 1 Eye Clinic Day Hospital 2 Federal University of São Paulo - UNIFESP São Paulo - Brazil The authors have no financial interest in the subject matter of this poster

2. Introduction Penetrating keratoplasty (PKP) is still widely performed as a treatment option for the correction of advanced keratoconus. However, visual rehabilitation is so far influenced by the presence of different degrees of refractive errors. Several surgical refractive treatments have already been proposed. Unfortunately, the amount of total higher-order aberrations (HOA) present in these eyes is faraway that observed in non operated eyes. This may influence the visual quality experienced by these patients. Many wavefront sensors have more difficulty of measuring the ocular aberrations on eyes with highly irregular corneas. Inaccuracies in wavefront measurements may compromise clinical testing and the refractive correction procedures. Another concern is the presence of possible discrepancies between the wavefront-derived refractions and the clinical measurements, since many customized ablation platforms use these data to treat the refractive error.

3. Purpose To analyze ocular order aberrations derived from Ladarwave (Alcon) and Zywave (Bausch & Lomb) devices in eyes after penetrating keratoplasty (PKP) for keratoconus (KC) and to compare the clinical refraction with the lower order aberrations obtained from these two aberrometers

4. Methods Inclusion criteria Minimum age: 18 yo History of PKP for KC Clear corneal graft Previous removal of all keratoplasties sutures Exclusion criteria Other ocular pathology than KC Other previous surgery than PKP Contact lens wear Thirty eyes were evaluated with 2 wavefront (WF) sensors: Ladarwave and Zywave

5. Methods The WF refractions were evaluated for 3.50mm pupil and compared with the clinical measurements (manifest and cycloplegic), after conversion to power vectors coordinates: spherical equivalent (M or Sph Eq), J 0 and J 45 (astigmatism) (1) The WF aberrations (up to the 4 th order) were compared between the 2 devices (6.00mm pupil size) Parametric testing was used with a significant level of p < 0.05 (1) Thibos LN, Wheeler W, Horner DG. Power vectors: an application of Fourier analysis to the description and statistical analysis of refractive error. Optom Vis Sci 1997;74:367-375.

6. Results The mean time between PKP and WF examinations was: 5.95±4.37 years (range, 1 to 15 years) The Zywave aberrometer was unable to capture the images in 3 eyes and the Ladarwave in one of them Centroids view and processed image in post PKP eye Note the irregularities at the periphery

7. Results Correlation between the manifest and the Ladarwave and the Zywave derived refraction Manifest refractionLadarwaveZywave Sph Eq r = 0.97 p < 0.001 * r = 0.97 p < 0.001 * Vector J 0 r = 0.97 p < 0.001 * r = 0.97 p < 0.001 * Vector J 45 r = 0.92 p < 0.001 * r = 0.94 p < 0.001 * Both wavefront devices derived refractions were highly correlated to clinical manifest refraction

8. Results Cycloplegic refraction LadarwaveZywave Sph Eq r = 0.99 p < 0.001 * r = 0.99 p < 0.001 * Vector J 0 r = 0.97 p < 0.001 * r = 0.95 p < 0.001 * Vector J 45 r = 0.91 p < 0.001 * r = 0.94 p < 0.001 * Correlation between the cycloplegic and the Ladarwave and the Zywave derived refraction Both wavefront devices derived refractions were highly correlated to clinical cycloplegic refraction

9. Results VariablesClinical RefractionWF sensor derived-refraction ManifestCycloplegicLadarwaveZywave Mean Sph Eq (SD)-3.65 (3.75)-2.98 (3.99)-3.30 (4.20)-2.80 (4.18) Range-15.00 to 1.75-15.00 to 3.38-16.09 to 3.61-15.49 to 4.02 Mean J 0 (SD)0.34 (1.62)0.23 (1.77)0.31 (2.01)0.11 (2.13) Range-2.13 to 3.20-2.11 to 3.45-2.99 to 3.78-3.03 to 3.78 Mean J 45 (SD)-0.29 (1.41)-0.25 (1.67)-0.29 (1.67)-0.27 (1.54) Range-2.17 to 2.75-2.35 to 2.57-4.42 to 2.84-3.09 to 2.49 Statistically significant differences (p < 0.05) were found between: LADARWave Sph Eq and Zywave Sph Eq LADARWave J 0 and Zywave J 0 Zywave SphEq and the manifest Sph Eq LADARWave Sph Eq and the cycloplegic Sph Eq Analysis of variance with repeated measurements of the clinical and the wavefront sensors-derived refractions

10. Results Mean values of total HOA, 3 rd and 4 th HOA No statistically significant discrepancies in higher-order aberrations (HOA) measurements between the two Hartmann-Shack devices were observed. Trefoil aberrations were dominant when compared to coma or spherical aberrations in post-PKP eyes. (6.00mm pupil)

11. Conclusions Eyes with PK have a great amount of ocular aberrations The correction of these aberrations may be limited by the discrepancies among the wavefront refractions and the clinical measurements, since these customized ablation platforms use their own data to treat the refractive error

12. References Chalita, M. R. and R. R. Krueger (2004). "Wavefront aberrations associated with the Ferrara intrastromal corneal ring in a keratoconic eye." J Refract Surg 20(6): 823-30. Jafri, B., X. Li, et al. (2007). "Higher order wavefront aberrations and topography in early and suspected keratoconus." J Refract Surg 23(8): 774-81. Maeda, N., T. Fujikado, et al. (2002). "Wavefront aberrations measured with Hartmann-Shack sensor in patients with keratoconus." Ophthalmology 109(11): 1996-2003. McLaren, J. W., S. V. Patel, et al. (2009). "Corneal wavefront errors 24 months after deep lamellar endothelial keratoplasty and penetrating keratoplasty." Am J Ophthalmol 147(6): 959-65, 965 e1-2. Okamoto, C., F. Okamoto, et al. (2008). "Higher-order wavefront aberration and letter-contrast sensitivity in keratoconus." Eye 22(12): 1488-92. Pantanelli, S., S. MacRae, et al. (2007). "Characterizing the wave aberration in eyes with keratoconus or penetrating keratoplasty using a high-dynamic range wavefront sensor." Ophthalmology 114(11): 2013-21. Pesudovs, K. and D. J. Coster (2006). "Penetrating keratoplasty for keratoconus: the nexus between corneal wavefront aberrations and visual performance." J Refract Surg 22(9): 926-31. Reinstein, D. Z., T. J. Archer, et al. (2009). "Combined corneal topography and corneal wavefront data in the treatment of corneal irregularity and refractive error in LASIK or PRK using the Carl Zeiss Meditec MEL 80 and CRS-Master." J Refract Surg 25(6): 503-15. Shah, S., S. Naroo, et al. (2003). "Nidek OPD-scan analysis of normal, keratoconic, and penetrating keratoplasty eyes." J Refract Surg 19(2 Suppl): S255-9. Smolek, M. K. and S. D. Klyce (2003). "Zernike polynomial fitting fails to represent all visually significant corneal aberrations." Invest Ophthalmol Vis Sci 44(11): 4676-81. Thibos, L. N. and D. Horner (2001). "Power vector analysis of the optical outcome of refractive surgery." J Cataract Refract Surg 27: 80-85. Vinciguerra, P., E. Albe, et al. (2009). "Refractive, topographic, tomographic, and aberrometric analysis of keratoconic eyes undergoing corneal cross-linking." Ophthalmology 116(3): 369-78. Yoon, G., S. Pantanelli, et al. (2008). "Comparison of Zernike and Fourier wavefront reconstruction algorithms in representing corneal aberration of normal and abnormal eyes." J Refract Surg 24(6): 582-90.