Study About The Effect Of Intravitreal Injection With Domestic Avastin On Retina

PURPOSE: To study whether it is toxic for animal's retinal structure and function when injected different dosage of Avastin to its vitreous chamber and discuss the safe dosage.METHODS: 32 healthy adult rabbits were at random divided into three experimental groups and a control group. In the experimental group, each rabbit's right eye vitreous chamber was respectively injected Bevacizumab 4.2mg/0.2ml,0.42mg/0.2ml, 0.042mg/0.2ml. In the control group, each rabbit's right eye vitreous chamber was respectively injected equal amount of balanced salt solution. Before and after injection, 3rd, 6th, 9th, 12th, 14thd ophthalmotonometer, slit-lamp, ophthalmoscope examinations were performed and were taken pictures for their eyeground. Before and after injection,7th,14th d ERG examination was performed;The eye-balls of 7th d,14th d were taken and tissue structure of retina were observed under optical microscope.RESULT:1. fundus examination: It is normal for vitreous body and retina during the time of observation for15d in control group and 0.42mg, 0.042mg. After injection, there is a little cloudiness like grey ball in one of eye vitreous bodies in 4.2mg group. The picture of its eyeground is not clear. Cloudiness in 12d is not serious. Picture of 14d optical fundus is nearly normal.2. Intraocular pressure examination: after injecting drug and balanced salt solution for experimental group and control group, intraocular pressure in both groups rises a little. It is clearly seen in 3d and 6d after injection. Later it recovered gradually. It is meaningless in statistics for their difference in intraocular pressure comparision between groups(P>0.05).3. ERG examination:after injection ERG b wave amplitude of vibration lowers in 7d and rises in 14d; it is not obvious in control group. ERG b wave in 4.2mg group lowers less than other two dose groups and control group. Comparing 4.2mg group with other two groups and control group respectively, the difference is of statistic meaning(P<0.05).comparing 0.42mg,0.042mg and control group between them respectively, it is no statistic meaning (P>0.05).4. optical microscope observation: it appears normal for retinal structure in 7d,17d of control group,0.42mg group and 0.042 group. A few cells in inner stratum nucleare of 7d in group 4.2mg appear a little turgescent and gathering at the side of the nuclear; In 14d, the structure of inner and external layer and nerve fiber layer becomes disorder slightly and several ganglion cells are vacuolar degeneration. Others are nearly normal.5. EM observation: retinal ultrastructure of 7d,14d in control group,0.42group and 0.042 group is clear and no abnormal appears. It is seen that outer plexiform layer fissure in 7d of 4.2mg group widens. Inner nucleare layer cells in 14d become vacuolar. Bipolar cell wall is dilated and relaxed.Conclusions: Bevacizumab below 0.42mg ( including 0.42mg) was injected into Vitreous chamber. In the short term, it didn't have obvious effect on animals'retinal tissue structure and the function of nerve conduction...