Influence of the time of day on axial length and choroidal thickness changes to hyperopic and myopic defocus in human eyes

Daniel Moderiano; Michelle Do; Sam Hobbs; Vy Lam; Simran Sarin; David Alonso-Caneiro; Ranjay Chakraborty

doi:10.1016/j.exer.2019.03.019

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Influence of the time of day on axial length and choroidal thickness changes to hyperopic and myopic defocus in human eyes

Journal article

Peer reviewed

Influence of the time of day on axial length and choroidal thickness changes to hyperopic and myopic defocus in human eyes

Daniel Moderiano, Michelle Do, Sam Hobbs, Vy Lam, Simran Sarin, David Alonso-Caneiro and Ranjay Chakraborty

Experimental Eye Research, Vol.182, pp.125-136

2019

DOI: https://doi.org/10.1016/j.exer.2019.03.019

PMID: 30926510

Abstract

Axial length

Choroidal thickness

Hyperopic defocus

Myopia

Myopic defocus

Time of day

Research in animal models have shown that exposing the eye to positive or negative spectacle lenses can lead to predictable changes in eye growth. Recent research indicates that brief periods (1–2 h) of monocular defocus results in small, but significant changes in axial length and choroidal thickness of human subjects. However, the effects of the time of day on these ocular changes with defocus are not known. In this study, we examined the effects of monocular myopic and hyperopic defocus on axial length and choroidal thickness when applied in the morning (change between 10 a.m. and 12 p.m.) vs the evening (change between 5 and 7 p.m.) in young adult human participants (mean age, 23.44 ± 4.52 years). A series of axial length (using an IOL Master) and choroidal thickness (using an optical coherence tomographer) measurements were obtained over three consecutive days in both eyes. Day 1 (no defocus) examined the baseline ocular measurements in the morning (10 a.m. and 12 p.m.) and in the evening (5 and 7 p.m.), day 2 investigated the effects of hyperopic and myopic defocus on ocular parameters in the morning (subjects wore a spectacle lens with +3 or −3 DS over the right eye and a plano lens over the left eye between 10 a.m. and 12 p.m.), and day 3 examined the effects of defocus in the evening (+3 or −3 DS spectacle lens over the right eye between 5 and 7 p.m.). Exposure to myopic defocus caused a significant reduction in axial length and thickening of the subfoveal choroid at both times; but, compared to baseline data from day 1, the relative change in axial length (−0.021 ± 0.009 vs +0.004 ± 0.003 mm, p = 0.009) and choroidal thickness (+0.027 ± 0.006 vs +0.007 ± 0.006 mm, p = 0.011) with defocus were significantly greater for evening exposure to defocus than for the morning session. On the contrary, introduction of hyperopic defocus resulted in a significant increase in axial length when given in the morning (+0.026 ± 0.006 mm), but not in the evening (+0.001 ± 0.003 mm) (p = 0.047). Furthermore, hyperopic defocus resulted in a significant thinning of the choroid (p = 0.005), but there was no significant influence of the time of day on choroidal changes associated with hyperopic defocus (p = 0.672). Exposure to hyperopic and myopic defocus at different times of the day was also associated with changes in the parafoveal regions of the choroid (measured across 1.5 mm nasal and temporal choroidal regions on either side of the fovea). Our results show that ocular response to optical defocus varies significantly depending on the time of day in human subjects. These findings represent a potential interaction between the signal associated with the eye's natural diurnal rhythm and the visual signal associated with the optical defocus, making the eye perhaps more responsive to hyperopic defocus (or ‘go’ signal) in the morning, and to myopic defocus (or ‘stop’ signal) in the latter half of the day. •Ocular response to defocus varies depending on the time of day in human subjects.•Evening exposure to myopic defocus causes a larger reduction in axial length.•Only morning exposure to hyperopic defocus causes an increase in axial length.•Axial length changes are associated with opposite changes in choroidal thickness.•Ocular diurnal rhythms may influence the eye's response to defocus in humans.

Details

Title: Influence of the time of day on axial length and choroidal thickness changes to hyperopic and myopic defocus in human eyes
Authors: Daniel Moderiano (Author) - Flinders University
Michelle Do (Author) - Flinders University
Sam Hobbs (Author) - Flinders University
Vy Lam (Author) - Flinders University
Simran Sarin (Author) - Flinders University
David Alonso-Caneiro (Author) - Queensland University of Technology
Ranjay Chakraborty (Corresponding Author) - Flinders University
Publication details: Experimental Eye Research, Vol.182, pp.125-136
Publisher: Academic Press
DOI: 10.1016/j.exer.2019.03.019
ISSN: 1096-0007
PMID: 30926510
Organisation Unit: School of Science, Technology and Engineering
Language: English
Record Identifier: 99972396402621
Output Type: Journal article