Optimizing Prediction of Refraction through Metrics Calculations for simulated Keratoconic subjects

Abstract

Purpose : To determine how many orders are needed to optimize refraction for simulated keratoconic subjects.

Methods : We simulated 100 keratoconic patients aberrations thanks to a numerical model. Zernike coefficients were used to calculate the HORMS (high order root mean square) metric and power vectors M, J₀, and J₄₅. HORMS and power vectors were calculated for orders up to the 2^nd, 4^th, 6^th, 8^th and 10^th order.

Results : T-test analysis showed a significant difference between the 2^nd order compared to higher order aberrations for HORMS (4^th, 6^th, 8^th, and 10^th : p<0.05 for all cases). There was no significant difference between any combination of higher order aberration comparisons for HORMS (i.e. 4^th, 6^th, 8^th and 10^th : p>0.05 in all cases). There was also a significant difference between the 2^nd order compared to higher order aberrations (4^th, 6^th, 8^th and 10^th order : p<0.05) for all power vectors (M, J0 and J45). However, there was no significant difference between any combination of higher orders (4^th, 6^th, 8^th and 10^th order : p>0.05) for all power vectors (M, J0 and J45).

Conclusions : Correcting Zernike polynomials up to the 4^th order will optimize prediction of refraction in Keratoconic patients. Beyond 4^th order, there are no significant changes in power vectors, and therefore in refraction. This information could be used to develop new soft contact lenses and spectacles as custom treatments for later stages of the disease through wavefront analysis for refraction optimization.

This is a 2020 ARVO Annual Meeting abstract.