Abstract
Previous studies have shown cognition to have an influence on accommodation. Temporal variation in the accommodative response occurs during the fixation on a stationary target. This constantly shifting response has been called accommodative micro-fluctuations (AMFs). The aim of this study is to determine the effects of increasing task cognitive demand on the ocular accommodation response. AMFs for 12 myopes and 12 emmetropes were measured under three conditions of varying cognitive demand and comprising reading of numbers (Num), simple arithmetic (SA), and complex arithmetic (CA). Fast Fourier transforms were used to analyze the different frequency band components of the AMFs. Other aspects of AMFs including root mean square accommodation values and chaos analysis was applied. A repeated measures ANOVA revealed a significant main effect of cognition in the mean power of the high frequency component (HFC) (F2,44 = 10.03, p < 0.005). Pairwise analyses revealed that these differences exist between SA and CA tasks (p < 0.005) and the Num and CA (p < 0.005) tasks with the HFC power being the highest for the CA condition. It appears that the difficulty of a task does affect active accommodation but to a lesser extent than other factors affecting accommodation.
Highlights
IntroductionTemporal variation in the accommodative response occurs during the fixation on a stationary target and this constantly shifting response has been termed accommodative micro-fluctuations (AMFs) [1,2]
An accurate ocular accommodation response is a requirement for pre-presbyopes to minimize retinal defocus and maintain clear viewing of a near-work task.Temporal variation in the accommodative response occurs during the fixation on a stationary target and this constantly shifting response has been termed accommodative micro-fluctuations (AMFs) [1,2]
The Refractive Error group was found to have no significant effect on the mean accommodative response
Summary
Temporal variation in the accommodative response occurs during the fixation on a stationary target and this constantly shifting response has been termed accommodative micro-fluctuations (AMFs) [1,2]. These AMFs are approximately 0.50 D in amplitude [3]. Fast Fourier Transforms (FFTs) have indicated that the AMFs consist of two main contributing frequencies bands. This includes a high frequency component (HFC, typically between 1.0 and 2.3 Hz) and a low frequency component (LFC, frequencies below 0.6 Hz) [1,3,4,5,6]. There is still much uncertainty about this [3]
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