Abstract
Purpose :
To evaluate the multifocal properties of 16 multifocal designs when interacting with the higher order aberrations (HOA) naturally occurring in a pool of 782 subjects (1564 eyes in total). In this work we have identified: the best design for each eye, the best combination of designs for a binocular through focus correction, and the optical difference between the best correction possible available for each subject and the reversed correction.
Methods :
A computer model was developed to test the optical performance of one monofocal design and sixteen multifocal designs. The multifocal designs include 8 bifocal, 4 trifocal, and 4 designs with 4 foci. The optical properties (VSOTF) of the interaction with the HOAs naturally occurring in a patient population of 782 subjects were also calculated. The area under the curve, the range above threshold, and the optical disparity between both eyes were used as the indexes to evaluate the optical performance of such interactions. Calculations were performed for a pupil diameter of 4 mm.
Results :
Bifocal designs, regardless of the orientation of the division offer better optical performance (area under the curve) than the monofocal, trifocal, and than designs with 4 foci. When the optical aberrations occurring in a normal patient population are introduced, bifocal designs with a left right separation offer the best optical performance (N-F=13%, F-N=15%). When the best combination of designs is changed (left eye correction-> right eye, right eye correction->left eye), the interval above threshold decreases a 15%, the area under the VSOTF decreases a 3.7% on average across subjects, and optical disparity increases a 7%.
Conclusions :
1- Bifocal designs offer better optical properties through focus than monofocal, trifocal or 4-foce designs designs. 2- When interacting with the natural aberrations of a large subject population, designs with a left-right separation for near-far (or far-near) offer the best optical properties. 3- When prescribing multifocal solutions to a subject, HOAs have to be measured and taken into account when selecting the design; special interest has to be given to coma and spherical aberration terms. 4- Although ocular dominance is a usual criterion in monovision solutions for deciding which eye is used for near and which for far, a new factor representing the optical profile given by the natural aberrations of the subject’s eyes should be introduced in the criteria.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.