Impact of higher-order aberrations on depth-of-field

Abstract

Purpose : Extending depth-of-field (DoFi) of the eye by inducing higher-order aberrations (HOAs) has been of great interest as a potential optical correction for presbyopia. We performed a study to assess the impact of natural HOAs on DoFi, and to investigate whether same HOAs patterns have equal effect on DoFi of different participants. This knowledge will be of interest particularly to better understand if a subject would benefit from an optical correction for presbyopia that extends DoFi by inducing HOAs.

Methods : Eleven participants (7 males and 4 females) between 21 and 54 (mean 33.55 ± 11.12) years of age participated in the study. Participants had no ocular pathology and spherical equivalent refractive error was between –3.50 D and +2.00 D. A custom made adaptive optics system was used to measure subjective DoFi under 3 conditions: (1) with natural HOAs, (2) with HOAs corrected, and (3) exchanging HOAs between some participants. Accommodation was paralysed with a cycloplegic to avoid its effect on DoFi measurements. Participants took a 6 minute period prior to the measurements to get adapted to each condition.

Results : The mean difference between DoFi with natural HOAs and with HOAs corrected was 0.26 D (p < 0.05). Figure 1 shows this difference for individual subjects. Different DoFi were obtained with the same pattern of HOAs applied to different subjects (condition 3). The DoFi difference when a new HOAs pattern is simulated and the natural condition is significantly correlated with changes in fourth-order spherical aberration (r² = 0.16, p < 0.05) and sixth-order spherical aberration (r² = 0.43, p < 0.05).

Conclusions : Subjective DoFi is influenced by HOAs, but the small mean difference when HOAs are corrected suggests that neural factors have a greater effect. Correcting HOAs or inducing new ones has a different effect on subjects’ DoFi and this effect is mainly explained by the presence of spherical aberration. Thus, trying to extend DoFi by manipulating HOAs would be most beneficial when done on a case-by-case basis.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Figure 1. Subjective DoFi of all participants with their natural HOAs (black circles) and with all HOAs corrected (white squares). Error bars represent ± 1SEM.