Interocular differences in myopia and the depth of the vitreous chamber of the eyes (VCD) with monocular diffusers under different temporal cycles of bright light.

<p>*significant myopic shifts in deprived eyes compared to non-deprived fellow eyes.</p><p>Interocular differences in myopia and the depth of the vitreous chamber of the eyes (VCD) with monocular diffusers under different temporal cycles of bright light.</p

Relative increase in vitreous chamber depth (VCD) in eyes with monocular diffusers (bars grey-scale coded as in Figure 1).

<p>Although there was no significant difference among treatment groups for either paradigm (Paradigm I: F = 1.639, P = 0.204 and Paradigm II: F = 2.075, P = 0.109), the increase of VCD in chickens reared under constant bright light for 5 or 10 hours was signifcantly supressed compared with those under standard illuminance (P = 0.029 and 0.037, respectively). In comparison with constant bright light, this effect was further enhanced in chickens exposed to cycles of bright light at a frequency of 7∶7 or 1∶1 minutes (all P<0.05, except for the comparison between the 7∶7 minute cycle and the 5 h constant bright light exposure, P = 0.180 and a borderline significance between the 7∶7 minute cycle and the 1 h constant bright light exposure, P = 0.075).* <0.05, **<0.01. Abbreviations as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110906#pone-0110906-g001" target="_blank">Figure 1</a>.</p

Myopia induced by diffusers over one eye when chickens were kept under constant bright light of 15 000 lux for 1, 2, 5, or 10 hours (“15k, time in hours”; filled gray bars) or under cycles of bright light, changing from 500 to 15 000 lux at different frequencies (“15k, half cycle duration; black bars).

<p>Patterned gray bars show the amount of myopia that developed in two batches of chickens wearing monocular diffusers under regular laboratory illumination of 500 lux (“500,10 h”). Because there was no difference between both groups, their data were pooled and provided the reference for the bright light treatment groups. An inhibitory effect of constant bright light was observed only when the exposure lasted for 5 hours or more (P = 0.004 and P = 0.007 for 5 and 10 hours, respectively). No additional benefit was observed when the bright light exposure was extended to 10 hours, compared with those exposed to 5 hours (P = 0.796). When bright light was provided as a temporal square wave function, its protective effect against myopia was enhanced. Chickens kept under 7∶7 or 1∶1 minute cycles developed the least myopia, compared with other cycles (P = 0.033 for differences among groups reared under cycles of bright light; Post-hoc pairwise comparison: 7∶7 minutes vs 30∶30 minutes, P = 0.038; 1∶1 minutes vs 60∶60, 30∶30, 15∶15 minutes: P = 0.041, 0.006, 0.022, respectively). *<0.05, **<0.01.</p

Correlation between vitreous chamber depth and the amount of myopia in chickens under different light regimens.

<p>Equations for the linear regression, and R² values are provided for each light regimen. Long dash line represents the data for intermittent bright light, dotted line for constant bright light and short dash line for standard illuminance, respectively. Note that one diopter of myopia was equivalent to about 0.1 mm of axial elongation across groups (data from one single animal were excluded from the plot because of apparent measurement error, data: −13.9D vs 0.25 mm).</p

Time-Course of Changes in Choroidal Thickness after Complete Mydriasis Induced by Compound Tropicamide in Children

<div><p>Purpose</p><p>The aim of this study was to investigate the time-course of changes in choroidal thickness (ChT) following complete mydriasis induced by compound tropicamide.</p><p>Methods</p><p>ChT was measured by OCT with the enhanced-depth imaging technique (Spectralis HRA+OCT, Heidelberg Engineering, Germany) at nine locations of the fundus: subfoveal ChT (SFChT) and ChT at 1 mm and 3 mm from the fovea in four quadrants. Mydriasis was induced with compound tropicamide (0.5% tropicamide plus 0.5% phenylephrine hydrochloride, three doses at 5-minute intervals). Measurements were conducted prior to the instillation and at 0, 30, and 60 min following complete mydriasis. Results at different time-points were compared using repeated-measures ANOVA to investigate the time-course of the changes.</p><p>Results</p><p>Thirty-nine subjects (mean age 11.9±2 years; 16 males and 23 females) were enrolled in the study. Compound tropicamide resulted in a statistically significant decrease in SFChT at 0, 30, and 60 min after complete mydriasis, as compared to baseline (−5±4 μm, −12±4 μm, and −13±4 μm, respectively; all P<0.0001). No significant changes were detected in the parafoveal choroid except at 1 mm temporal (T_1mm) and nasal (N_1mm) to the fovea at 30 and 60 min (T_1mm: −6±4 μm and −7±5 μm at 30 and 60 min; N_1mm: −6±4 μm and −7±5 μm at 30 and 60 min, respectively; all P<0.0001). Repeated-measures ANOVA showed a significant interaction between the time after complete mydriasis and the effect of the mydriasis agent.</p><p>Conclusions</p><p>Complete mydriasis induced by compound tropicamide led to choroidal thinning, and the magnitude varied over time.</p></div

Summary of time-points to measure the SFChT across studies.

<p>Summary of time-points to measure the SFChT across studies.</p

Summary of test-retest repeatability for ocular variables.

<p>Summary of test-retest repeatability for ocular variables.</p

Illustration of choroidal thickness (ChT) measurements in the fundus.

<p>(A) Fundus image showing horizontal and vertical scan lines going through the fovea. Choroidal thicknesses at 1 and 3 mm to the fovea superiorly, inferiorly, temporally, and nasally are marked as S_1mm, I_1mm, T_1mm, N_1mm, S_3mm, I_3mm, T_3mm, and N_3mm, respectively. (B) OCT image with horizontal scan. Left: temporal; right: nasal. OCT image shows SFChT, T_1mm, N_1mm, T_3mm, and N_3mm. (C) OCT image with vertical scan. Left: inferior; right: superior. OCT image shows SFChT, S_1mm, I_1mm, S_3mm, and I_3mm. Short horizontal lines in each dash-line in (B) and (C) indicate the borders measured for the choroid, and each figure indicates individual ChT in different locations.</p

Changes in ocular biometry over time after complete mydriasis.

<p>Changes in ocular biometry over time after complete mydriasis.</p

Effects of compound tropicamide on ChT after complete mydriasis.

<p>Effects of compound tropicamide on ChT after complete mydriasis.</p