Influence of Wavefront Aberration Order on Vision Prediction and Correction

Abstract

Purpose : To determine the number of Zernike polynomial orders that must be included in power vector and metric calculations to accurately predict the quality of vision or refractive correction using simulated eyes.

Methods : Biometry values of 100 simulated eyes were used to calculate the first 44 Zernike coefficients (i.e. up to the 8^th radial order) on a 5mm pupil diameter. The eyes were simulated using a previously published model that was based on real biometry data of healthy eyes. The wavefront Zernike coefficients were subsequently calculated and used to calculate power vectors M, J₀, and J₄₅. These may be used to predict low-order correction of patients and were calculated for all subjects in 4 different ways. The first group only used the 2^nd order Zernike coefficients to calculate the power vectors, while the second, third, and fourth groups used up to 4^th, 6^th, and 8^th order Zernike coefficients, respectively, to calculate the power vectors. We calculated the differences between the first and second group, second and third group, and third and fourth group for each of the 3 power vectors. A t-test with Bonferroni correction on the differences was used to assess significant differences between groups.

Results : There is a significant difference between all groups, except between the 2^nd and 4^th order for the J₄₅ power vector and between 6^th and 8^th order for the J₀ power vector. These results indicate that using up to the 8^th order would significantly affect power vector values, and consequently the predicted vision correction.

Conclusions : Using Zernike aberration terms up to the 8^th order to calculate the power vectors leads to significantly different predicted refractions than up the 6^th order, except for the J₀ power vector. This could be used to improve vision prediction and/or vision correction development. Non-customized contact lenses corrections for presbyopia, for example, only use aberrations up to the 6^th order. Using up to the 8^th order could improve the precision of the correction to enhance depth-of-focus. The next step would be to validate this result by asking volunteers to subjectively evaluate the difference in visual quality provided by corrections using up to 6^th and 8^th order aberrations.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.