A new method for better ocular wavefront analysis

Session Details

Session Title: Vision & Accommodation Assessment

Session Date/Time: Monday 24/09/2018 | 14:00-16:00

Paper Time: 14:00

Venue: Room A3, Podium 2

First Author: : D.Gatinel FRANCE

Co Author(s): :    J. Malet   L. Dumas                 

Abstract Details

Purpose:

Zernike polynomials are in widespread use for wavefront analysis because of their orthogonality over a circular pupil and their representation of balanced classical aberrations. Because of artefacts due to the presence of low order 1 and order 2 terms in higher order Zernike modes such as coma Z(3,1), spherical aberration Z(4,0), and secondary astigmatism Z(4,2), the order 2 coefficients do no predict with a good accuracy the wavefront deformation that can be corrected with eyeglasses or laser refractive surgery. We propose a new aberration function basis as alternatives of Zernike polynomials to represent the wavefront aberrations of human eyes.

Setting:

Rothschild Foundation, Paris, France

Methods:

A new decomposition method and basis are built. The separation between low and high order terms is strict. In this new basis, the analytical expression of the higher order modes (n≥3) does not contain terms of order 1 or order 2. New double index scheme polynomials G(n,m) are introduced to replace some high-order Zernike modes. These polynomials are free of low-order terms.

Results:

Ocular wavefront error can be decomposed into the sum of G(n,m) polynomials of low degree (n <= 2) and of high degree (n <= 3). When the higher order aberrations increase (keratoconus, complicated refractive surgery, multifocal ablations), the 2nd-degree modes of the new basis should better correlate with the clinical refraction. Clinically relevant terms such as coma G(3,±1), spherical aberration G(4,0) and secondary astigmatism G(4±2) are weighted by more prominent coefficients than the Zernike basis. This may facilitate the clinical interpretation and comparison of the aberrations within the higher order wavefront component.

Conclusions:

Because it better separates the lower vs higher order aberration components, the new aberration classification and basis may quantify more accurately the aberrations that contribute to the spectacle refractive error, design more accurate customized corrections and provide clinicians with coefficients magnitudes which better underline the impact of clinically significant aberration modes.

Financial Disclosure:

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