Study On The Experimental Model Of Different Wavelength Lasers-induced Choroidal Neovascularization In Guinea Pigs With High Myopia Induced By Form Deprivation

Objective To explore the the feasibility of the animal model building of choroidalneovascularization due to high myopia in guinea pigs.Methods1. Rupture of Bruch’s membrane: Nine animals with anisometropia greaterthan6.00D were randomly assigned to3groups:7d,14d,28d. All thegroups underwent biometric measurement (refraction). The eye of highermyopia was taken as the treatment eye, the other was the control eye. Alleyes were received a series of different wavelength laser (532nm)photocoagulation (400mW,50μm,0.1s). Fundus photography andindocyanine green angiography (ICGA) were performed, then the animalswere sacrificed immediately, the eyes were enucleated and processed forhistopathologic examination and flat mounts at each time point.2. No rupture of Bruch’s membrane:30animals with anisometropia lessthan2.00D were using facemask to induce high myopia in6weeks, thenused different wavelength laser (532nm) to perform a photocoagulation(120mW,200μm,0.1s) but not to make the rupture of the Bruch’smembrane. All of the animals then were randomly divided into3groupsafter photocoagulation:7d,14d,28d. Fundus photography and indocyaninegreen angiography (ICGA) were performed; then the animals weresacrificed immediately, the eyes were enucleated and processed foristopathologic examination and flat mounts at each time point. Themolecular biological analysis like immunohistochemistry for VEGF,MMP-2factor in the experimental eyes and control eyes were performed.Results1. The results showed that CNV was appeared at7d, reaching the peak at14d,and scarring at28d. The success rate of CNV model was66.7%according to ICGA results at14d. CNV could be observed by light microscopy at thethree time point. At14d, flat mount showed that the neovascular plexusaround the lesion. The semi-quantitative analysis showed that CNV area oftreatment eyes were greater than the control eyes, the CNV area of theexperimental eyes were the largest at14d, and CNV area were reduced at28days.2. The results showed that CNV was induced in the facemask eyes in guineapigs after photocoagulation at7d. The axial length of the facemask eyeswere significantly greater than the non-facemsk eyes and the eyes ofcontrol group, and the extended length was mainly the growth of thevitreous cavity. The ICGA demonstrated the CNV were formed at the threetime points in the facemask eye. Subretinal CNV were found at7d afterphotocoagulation, reached a peak at14d, and scarring at28d.Immunohistochemical results showed that VEGF highly expressed in thechoriocapillaris of the form deprivation eye, the expression of MMP-2washigher in the retinal pigment epithelium in the form deprovation eye than inthe control eye.Conclusion According to the results, we assumed that greater CNV area in highermyopia eyes may be associated with retinal and choroid thinning due to theaxial growth, which lead to more ischemia and hypoxia. CNV could beinduced on the eyes of induced high myopia by different wavelength laser,which did not make the rupture of Bruch’s membrane in guinea pigs. TheVEGF and MMP-2was involved in the process of formation of highlymyopic CNV in the model. Since the mechanism of CNV formation in thisstudy is more similar to human pathologic myopia CNV, the model can beused in the etiology, pathogenesis and drug treatment study of CNV due topathologic myopia.