Abstract
Abstract: :
Purpose: To describe analytical formulas of the effect of the pupil constriction on the wavefront analysis using Zernike polynomials. Methods: The first 21 Zernike terms (up to the fifth radial order) were assigned arbitrary coefficients and independently analyzed as a function of the pupil diameter reduction factor S (S= pupil diameter/largest normalized pupil) using scalar products. The effects of reducing pupil size on all 21 Zernike coefficients were determined for each coefficient. Results: For coefficients of the 2nd -5th order terms, reducing the pupil size resulted in greater reductions of the Zernike coefficient (proportional to S2, S3, S4 and S5) for 2nd, 3rd, 4th and 5th order terms, respectively. Additional coefficients of lower order were induced by pupil constriction for certain terms (coma inducing prism, spherical aberration inducing defocus, 5th order secondary coma inducing 3rd coma). Altering pupil diameter did not induce other terms when the only coefficient was of defocus, astigmatism and/or trefoil. Similar analysis was done for two higher even order rotationally- symmetric Zernike polynomials (Z60 and Z80) and resulted in induced defocus and spherical aberration upon pupil constriction. Conclusions: Pupillary constriction is beneficial in reducing optical aberrations by direct reducing of the Zernike coefficients. However, detrimental effect may be seen as a result of induced additional lower order coefficients.
Keywords: refractive surgery: optical quality • physiological optics • computational modeling