Abstract
Purpose :
Atropine is currently being used for myopia control but the exact mechanism is unknown. Previous work from our group using atropine 1% described an increase in choroid thickness that was greater than its diurnal change. The purpose of our current study is to determine the effect of low dose concentrations of topical atropine (0.1% and 0.01%) on choroidal thickness compared to its diurnal change in young healthy adults.
Methods :
The diurnal changes in axial length (AL) and subfoveal choroidal thickness (sCT) were measured in thirty-two adults (mean age 25.59 years, range 22-31) at SUNY Optometry (NY) using a Lenstar and Heidelberg Spectralis OCT, respectively. Baseline (BL) measures were first obtained throughout the day at 8am, 9am, 12pm, and 4pm. Subjects were then randomized to 1 drop of either 0.1% or 0.01% atropine in both eyes at 8am. Additional measures were made at 1, 4, and 8 hrs (9am, 12pm, and 4pm) following atropine instillation, and at 1-week following daily morning atropine instillation. After a 4-week washout period, the protocol and measurements were repeated for the alternative concentration (0.1% or 0.01%) of atropine.
Results :
Prior to atropine instillation, BL sCT (296.06±67.72µm) marginally increased from 8am to 9am by 2.13±67.02µm (p>0.05), and decreased by 4.23±66.43µm at 4pm. Following 8am instillation, atropine prevented diurnal sCT thinning and demonstrated sCT thickening throughout the day. Compared to BL, sCT increased at 12pm and 4pm with both low doses of atropine: 0.01% (9.48±16.96µm, 11.75±24.20µm, p<0.05 for both) and 0.1% (10.60±15.19µm, 11.05±19.10µm, p<0.05 for both). sCT significantly increased after 1-week of daily instillation of both low doses of atropine: 0.01% (20.36±23.79µm, p<0.05) and 0.1% (16.47±12.82µm, p<0.05). AL did not change throughout the day at BL or after atropine instillation. Both low doses of atropine decreased vitreous chamber depth (VCD), which mirrors the increase in sCT; however, VCD change was only significant at 4pm with atropine 0.1% (-31.60±62.13µm, p<0.05).
Conclusions :
Our current findings using low dose atropine 0.1% and 0.01% exhibit the same trend as atropine 1% and confirm that low dose atropine prevents diurnal thinning of the choroid and induces a thickening that is maintained throughout the day and increases further after a week of daily instillation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.