Abstract
Purpose :
To investigate the effect of lens-induced high myopia on posterior pole tissue thickness changes in tree shrews over time
Methods :
Tree shrews were randomly assigned to 2 groups: normal visual experience (n=5) or high myopia (n=7), where high myopia was induced in one eye using -10D lenses from 24 to 59 days of visual experience (DVE). Refractive (Nidek ARK-700A, Marco Ophthalmic) and biometric (Lenstar LS-900, Haag-Streit) measurements were performed daily. Longitudinal OCT raster scans of the posterior pole were acquired at baseline then follow-up scans (FUS) were obtained weekly x 5 using enhanced depth imaging (Spectralis OCT2, Heidelberg Engineering). The retina, choroid, RPE and sclera were manually delineated (see Fig.1) and their corresponding thicknesses were quantified and averaged over a 700 px range starting at 500 px from BMO (Fig.1). The final thickness values were determined as the average of 3 B-scans per eye. Significant differences in tissue thickness were investigated across groups and by pairwise comparisons using a factorial design ANOVA with post-hoc Bonferroni correction.
Results :
High levels of myopia developed in all lens treated eyes (-9.56±1.05 D). The statistical analysis showed a significant time by group interaction with the sclera (p=0.0001), choroid (p=0.007) and retina (p=0.0001) significantly thinner in all FUS in the lens-treated eyes compared to normal and control eyes. RPE thickness remained unchanged (p=0.272). Overall, the sclera and retina of the control eyes were significantly thicker (main effect) compared to normal eyes p=0.003 and p=0.0004, respectively. Results are summarized in Fig. 2.
Conclusions :
The tree shrew sclera, retina and choroid thin simultaneously during high myopia development. The majority of tissue thinning occurred during the first 7 days of lens treatment. Surprisingly, transient scleral thickening was seen in the control sclera. Our results support the notion that choroidal and retinal thinning can be used as biomarkers for scleral thinning and remodeling in the tree shrew lens-induced myopia model.
This is a 2020 ARVO Annual Meeting abstract.