The Effects And Mechanisms Of Racanisodamine On Form-deprivation Myopia In Guinea Pigs

PartⅠThe efficacy and safety of 10% racanisodamine on form-deprivation in guinea pigsPURPOSE To investigate the efficacy and safety of 10% racanisodamine on form-deprivation in guinea pigs.METHODS 30 guinea pigs aged 2 to 3 weeks were randomly distributed to 3 groups (n=10 for each group). Form-deprivation model was built in right eyes with a translucent membrane while the left eyes as control. Group A was form-deprivation with intravitreal injection of 20μl 10% racanisodamine for one time. Group B was form-deprivation with intravitreal injection of 20μl saline for one time. Group C was form-deprivation group. All animals were raised in 5001ux white light environment, with the lighting period of 12h a day. Axial length, anterior chamber depth and lens thickness were measured by ultrasound, and vitreous length was calculated. Refraction was measured by retinoscopy. Radius of corneal curvature was measured by keratometer. Measurements were carried out before and 2 weeks after intervention and the difference between right and left eye was evaluated to eliminate the intergroup disparity during growing. HE staining was performed to observe the microstructure of eyes under microscope.RESULTS There was no significant difference of the baseline value of biometric measurements(P>0.05). The difference in axial and vitreous length between right and left eye was significantly smaller in group A than in the other two (P＜0.05). The difference in vitreous length was significantly related to that in axial length (P<0.05). No significant difference between bilateral eyes was found in refraction, lens thickness, radius of corneal curvature or anterior chamber depth among the groups (P>0.05). No toxic change in cornea, retina, sclera or ciliary body was found after racanisodamine injection.CONCLUSIONS 10% racanisodamine may prevent the axial elongation of form-deprivation myopia in guinea pigs, mainly through the inhibition of vitreous length elongation. No toxic change was found after intravitreal injection of 10% racanisodamine. PartⅡInfluence of 10% racanisodamine on the expression of TGF-P2 and MMP-2 in posterior sclera in form-deprivation of guinea pigsPURPOSE To investigate the influence of 10% racanisodamine on the expression of TGF-β2 and MMP-2 in posterior sclera in form-deprivation in guinea pigs.METHODS 30 guinea pigs aged 2 to 3 weeks were randomly distributed to 3 groups (n=6 for each group). Group A was form-deprivation with intravitreal injection of 20μl 10% racanisodamine for one time. Group B was form-deprivation with transparent memberane on the right eye. Group C was normal control. Eyes from the 3 groups were enucleated after 2 weeks. Sclera of the posterior segment were separated with a diameter of 8 mm. MMP-2 and TGF-β2 expression was detected in sclera tissue with the method of western-blot.RESULTS MMP-2 expression in 10% racanisodamine injection group was higher than that in normal control group but lower than that in form-deprivation group. TGF-β2 expression in 10% racanisodamine injection group was higher than that in form-deprivation group but lower than that in normal control group.CONSLUSIONS Intravitreal injection of 10% racanisodamine may change the protein expression in posterior sclera. Racanisodamine may inhibit the exprssion of MMP-2 and increase that of TGF-β2. Whether such a mechanism takes part in sclera remodeling and affects the progression of myopia needs further study.