September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
The interaction between 2% homatropine and optical blur on the choroidal thickness of young healthy adults
Author Affiliations & Notes
  • Beata P Sander
    Queensland University of Technology, Kelvin Grove, Queensland, Australia
  • Michael J Collins
    Queensland University of Technology, Kelvin Grove, Queensland, Australia
  • Scott A Read
    Queensland University of Technology, Kelvin Grove, Queensland, Australia
  • Footnotes
    Commercial Relationships   Beata Sander, None; Michael Collins, None; Scott Read, None
  • Footnotes
    Support  NONE
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 5517. doi:
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      Beata P Sander, Michael J Collins, Scott A Read; The interaction between 2% homatropine and optical blur on the choroidal thickness of young healthy adults. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5517.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : This project aimed to assess the interaction between short periods of retinal image blur (imposed with spectacle lenses) and an anticholinergic agent on the choroidal thickness of young healthy adults.

Methods : Thirty young healthy adults (15 myopes and 15 emmetropes), aged 18-35 years participated in this randomized, placebo-controlled study. Choroidal thickness of the right eye was measured with a spectral domain OCT (SOCT- Copernicus HR) prior to, and then 30 and 60 minutes following the introduction of three types of optical blur (0 D, -3 D and +3 D) combined with the instillation of one drop of 2% homatropine or placebo (0.3% hydroxypropyl methylcellulose). Each combination of blur and pharmacological agent was tested on a separate day in randomized order. The pre- and post-treatment OCT scans (6 mm long horizontal and vertical foveal line scans) were manually segmented by a masked observer to calculate subfoveal choroidal thickness.

Results : Repeated measures ANOVA revealed significant main effects of the drug and optical blur on choroidal thickness, and a significant interaction between the drug and optical blur (all p<0.0001). Of most interest was the interaction between hyperopic blur and homatropine. The subfoveal choroid underwent a small but significant thinning after hyperopic blur and placebo (mean change: -7.2±1.4 μm and -11.3±2.9 μm after 30 and 60 minutes respectively) however in contrast to this, hyperopic blur and homatropine treatment led to small amounts of subfoveal choroidal thickening (mean change: +0.2±2.0 μm and +2.9±2.4 µm after 30 and 60 minutes respectively). The effects of myopic blur and placebo, myopic blur and homatropine, and homatropine alone, were similar, with increasing subfoveal choroidal thickness observed in all cases. There was no evidence of differences in choroidal response between refractive groups.

Conclusions : Instillation of homatropine, an anticholinergic agent, appears to block the thinning effect of hyperopic blur on choroidal thickness, but does not enhance the thickening effect of myopic blur. This suggests the possibility of different pathways in the eye’s response to myopic and hyperopic blur or that there is an upper limit on the capacity of the choroid to thicken in the short-term. These findings provide insights into the role of the cholinergic system in the choroid’s response to optical blur.

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

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