Corneal aberrations in keratoconic eyes: influence of pupil size and centering

SILVIA A COMASTRI; LILIANA I PEREZ; GERVASIO D PEREZ; GABRIEL MARTIN; ARTURO BIANCHETTI

Lima

Congreso; 7th Ibero-American Conference on Optics- 10th Latin-American Meeting on Optics, Lasers and Applications; 2010

Pontificia Universidad Católica del Perú

Ocular aberrations vary among subjects and under different conditions and arecommonly analyzed expanding the wavefront aberration function in Zernike polynomials. Inprevious articles, explicit analytical formulas to transform Zernike coefficients of up to 7thorder corresponding to an original pupil into those related to a contracted displaced new pupilare obtained. In the present paper these formulas are applied to 20 keratoconic corneas ofvarying severity. Employing the SN CT1000 topographer, aberrations of the anterior cornealsurface for a pupil of semi-diameter 3 mm centered on the keratometric axis are evaluated, therelation between the higher-order root mean square wavefront error and the index KISA%characterizing keratoconus is studied and the size and centering of the ocular photopic naturalpupil are determined. Using these data and the transformation formulas, new coefficientsassociated to the photopic pupil size are computed and their variation when coordinates originis shifted from the keratometric axis to the ocular pupil centre is analyzed.