New methodology to measure the dynamics of ocular wave front aberrations during small amplitude changes of accommodation

L Diaz-Santana,V Guériaux,S Gruppetta,G Arden

doi:10.1364/oe.15.005649

Abstract

We present a methodology to measure the systematic changes of aberrations induced by small changes in amplitude of accommodation. We use a method similar the one used in electrophysiology, where a periodic stimulus is presented to the eye and many periods (epochs) of the stimulus are averaged. Using this technique we have measured changes in higher order aberrations from 0.006 mum to 0.02 mum and correlated them with amplitude changes of accommodation as small as 0.14D. These small changes would have been undetectable without epoch averaging. The correlation coefficients of Zernike terms with defocus were calculated, demonstrating higher values of correlation for epoch averaging. The accurate monitoring of defocus at the start of the accommodation response has shown some interesting trends that may be related with the mechanisms behind accommodation.

Highlights

The human eye is a dynamic system: ocular movements, saccades, blinking, changes in accommodation and pupil size and configuration of the tear film, amongst other physiological changes are a continuous response of the eye to maintain a clear retinal image
In the case of the eye, if we present a temporally periodic stimulus that induces accommodation changes, and it is true that the accommodation response will be constant to a particular stimulus, we can use this technique to study the very small changes in aberrations that are induced by accommodation alone
In this paper we have presented a methodology to measure the systematic changes of aberrations induced by changes in accommodation with small amplitudes

Summary

Introduction

The human eye is a dynamic system: ocular movements, saccades, blinking, changes in accommodation and pupil size and configuration of the tear film, amongst other physiological changes are a continuous response of the eye to maintain a clear retinal image. It has been known for more than two centuries that aberrations affect the optical quality of the eye [1]. An aberration free eye would produce a perfectly regular pattern of spots Such an image is usually referred as a reference frame and the beam producing it as a reference beam. The dynamics of these aberrations beyond defocus and astigmatism have not been as extensively studied [3, 4, 5, 6, 7, 8]

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