Regional Changes in Retinal and Choroidal Thickness in Lens-Induced Myopic Guinea Pigs

To investigate the variations in retinal thickness and choroidal thickness at different distances from the optic disk in the guinea pigs.

Twenty 3-week-old pigmented guinea pigs were randomly divided into a normal control group and a lens-induced myopia group. The normal control group received no intervention, while the lens-induced myopia group wore a -10D lens on the right eye to induce myopia and a 0D lens on the left eye as control. Refraction, axial length, corneal curvature radius, vitreous chamber depth, retinal thickness, and choroidal thickness were measured at baseline, 2 and 4 weeks. Centered on the optic disk, concentric circles with radii of 1000, 1500, 2000, and 2500 μm were drawn using Image J software (Bethesda, MD) to partition the retina and choroid.

After 4 weeks, lens-induced myopia-eyes showed lower refraction (lens-induced myopia vs. normal control, -1.38 ± 0.91D vs. 2.64 ± 0.76D, p < 0.0001), retinal thickness (lens-induced myopia vs. normal control, 149.14 ± 4.64 μm vs. 159.63 ± 4.64 μm, p < 0.0001) and choroidal thickness (39.07 ± 3.30 μm vs. 45.80 ± 5.32 μm, p < 0.01), and increased axial length (lens-induced myopia vs. normal control, 8.34 ± 0.20 mm vs. 8.01 ± 0.16 mm, p < 0.0001) and vitreous chamber depth (lens-induced myopia vs. normal control, 3.87 ± 0.11 mm vs. 3.50 ± 0.11 mm, p < 0.0001) compared with the normal control group and Fellow-eye. At week 4, retinal thickness at all positions of the lens-induced myopia-eye differed from normal control and Fellow-eye, while choroidal thickness differed only at 1500 μm and 2000 µm. Thinning of retinal thickness and choroidal thickness are both at distances of 1500 μm and 2000 μm. Mean retinal thickness and choroidal thickness correlated positively with refraction, but the changes in retinal thickness and choroidal thickness at each position are not correlated with the changes in RE.

The structural changes in the retina and choroid during myopia progression are region-specific rather than uniform across the posterior pole.