Background: To test the hypothesis that 0.01% atropine eyedrops are a safe and effective myopia-control approach in Australian children.Methods: Children (6-16 years; 49% Europeans, 18% East Asian, 22% South Asian, and 12% other/mixed ancestry) with documented myopia progression were enrolled into this single-centre randomised, parallel, double-masked, placebo-controlled trial and randomised to receive 0.01% atropine (n = 104) or placebo (n = 49) eyedrops (2:1 ratio) instilled nightly over 24 months (mean index age = 12.2 ± 2.5 and 11.2 ± 2.8 years, respectively). Outcome measures were the changes in spherical equivalent (SE) and axial length (AL) from baseline.Samantha Sze-Yee Lee and Gareth Lingham contributed equally to this study.
Contemporary research in the field of forensic anthropology has been diversified and aided by the use of medical imaging technology, which is increasingly being utilised to produce estimates of chronological age as part of the biological profile of an unidentified deceased individual, or a living individual whose age is contested. Age vii Dedication I would like to dedicate this thesis to my parents, Iwona and Edward Kopczyk. I can say with complete certainty that I would not be where I am today without your bravery, self-sacrifice and dedication to improving my quality of life. I hope that this thesis comes to represent all that you have wished to provide for me. viii TABLE OF CONTENTS List of Figures .
Purpose
Changes in retinal thickness are common in various ocular diseases. Transverse magnification due to differing ocular biometrics, in particular axial length, affects measurement of retinal thickness in different regions. This study evaluated the effect of axial length and refractive error on measured macular thickness in two community-based cohorts of healthy young adults.
Methods
A total of 2160 eyes of 1247 community-based participants (18–30 years; 23.4% myopes, mean axial length = 23.6mm) were included in this analysis. Macular thickness measurements were obtained using a spectral-domain optical coherence tomography (which assumes an axial length of 24.385mm). Using a custom program, retinal thickness data were extracted at the 9 Early Treatment of Diabetic Retinopathy Study (ETDRS) regions with and without correction for transverse magnificent effects, with the corrected measurements adjusting according to the participant’s axial length. Linear mixed models were used to analyse the effect of correction and its interaction with axial length or refractive group on retinal thickness.
Results
The raw measures (uncorrected for axial length) underestimated the true retinal thickness at the central macula, while overestimating at most non-central macular regions. There was an axial length by correction interaction effect in all but the nasal regions (all p<0.05). For each 1mm increase in axial length, the central macular thickness is overestimated by 2.7–2.9μm while thicknesses at other regions were underestimated by 0.2–4.1μm. Based on the raw thickness measurements, myopes have thinner retinas than non-myopes at most non-central macular. However, this difference was no longer significant when the corrected data was used.
Conclusion
In a community-based sample, the raw measurements underestimate the retinal thickness at the central macula and overestimate the retinal thickness at non-central regions of the ETDRS grid. The effect of axial length and refractive error on retinal thickness is reduced after correcting for transverse magnification effects resulting from axial length differences.
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