Background
Our aim was to study the morphologic and functional changes in the retina and sclera induced by form deprivation high myopia (FDHM) in guinea pigs and explore the possible mechanisms FDHM formation.
Methods
Forty 3-weeks-old guinea pigs were randomized into the blank control (Group I, 20 cases) and model groups (20 cases). In the model group, the right eyes of the guinea pigs were sutured 8 weeks to induce FDHM (Group II) and the left eyes were considered a self-control group (Group III). The diopters were measured with retinoscopy. The anterior chamber depth (AC), lens thickness (L), vitreous depth (V) and axial length (AL) were measured using ultrasonometry A. Retinal and scleral morphology and ultrastructural features were observed with light and electron microscopy. The content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) in the retina and sclera were detected with a chemical colorimetric assay.
Results
After remaining stitched for eight weeks, the diopters of Group II changed from (+3.59±0.33) D to (-7.96±0.55) D, and these values were significantly higher than those of Group I (+0.89±0.32) D and Group III (-0.55±0.49) D. The vitreous chamber depth (4.12±0.13) mm and axial length (8.93±0.22) mm of Group II were significantly longer than that of Group I [(3.71±0.23) mm and (7.95±0.37) mm, respectively] and Group III [(3.93±0.04) mm and (8.01±0.15) mm, respectively] (P < 0.05). With the prolongation of form deprivation, the retina and scleral tissue became thinner, the ganglion cell and inner and outer nuclear layers of the retina became decreased, and the arrangement was disordered. In Group II, the activity of SOD was significantly lower than that in Group I and Group III, and the content of MDA was significantly higher in Group II than in Group I and Group III. The differences were statistically significant (P < 0.05).
Conclusions
These findings suggested that in the FDHM guinea pigs model, the diopter, the vitreous chamber depth, and axial length increased significantly with prolongation of monocular FD time, and morphological structural changes in the retina and sclera were observed. Oxygen free radicals might participate in the formation of FDHM.