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Christopher Patrick Taylor, Burke Leippman, Frances J Rucker; Imaging and cross-validation of chick choroid changes with spectacle lens wear using OCT. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5518.
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© ARVO (1962-2015); The Authors (2016-present)
When chicks wear positive spectacle lenses a compensatory increase in choroid thickness occurs (Wildsoet & Wallman, 1995). Optical coherence tomography (OCT) has been used to produce two-dimensional images of a single chick eye (Moayed et al., 2011), but has not been used to examine structural changes with lens-wear. We aimed to compare choroid thickness changes with OCT and noncontact ocular biometry and image the two-dimensional changes in the choroid with lens-wear.
Eight two-week old chicks wore +7D lenses on one eye for two days. The other eye served as a control. Chicks experienced a normal 12h light-dark cycle. Pre- and post- lens wear choroid thickness measures were taken with a noncontact ocular biometer (Lenstar LS 900; Haag-Streit AG, Konig, Switzerland) and an OCT system (Spark-1300 OCT; Wasatch Photonics, Durham, NC, USA). Ocular biometer measurements were analyzed as described previously (Feldkaemper, et al., 2012) and the choroid segmented from OCT images with custom software written in MATLAB using RPE and choroid-scleral boundaries as landmarks.
Lenstar biometry showed an increase in choroid thickness in the experimental versus control eye (0.16 ± 0.049 mm) with paired t-tests (p = 0.011, Cohen’s d = 1.94). Analysis of the segmented two-dimensional OCT boundaries showed mean choroid thickening (0.095 ± 0.017 mm) with paired t-tests (p=0.001, Cohen’s d = 2.95). Figure 1 depicts the changes in choroid thickness for each method. There was a greater absolute magnitude of choroid thickness for the Lenstar measure. However, a comparison of the two methods using Spearman’s rank order correlation showed no changes in rank ordering of choroid changes. Examples of the two-dimensional changes are shown in Figure 2 with the grey lines showing the segmentation. The top image (2A) is of the retina of an experimental eye prior to lens-wear and the bottom image (2B) after lens-wear. The grey lines indicate the location determined by the segmentation algorithm.
OCT provides a measure of choroid changes consistent with previous experiments and a visualization of the changes to the 2D structure of the choroid.
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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