Experiment of vitreous liquefaction induced by C3F8.

To investigate the effect and safety of vitreous liquefaction induced by C3F8 (an inert gas) injected into vitreous cavit of rabbit eyes. 24 rabbits (48 eyes) were randomly divided into four groups, named group A, group B, group C and group D, with 6 rabbits in each group. The right eye in each rabbit was taken as the experimental eye while the left as the control eye. The experimental eyes in group A were injected with 0.1mL disinfectant air; the experimental eyes in group B, group C and group D were all injected with C3F8 0.1mL, 0.2mL and 0.3mL respectively after receiving anterior chamber penetration; and the controlled eyes in all group were injected with 0.1mL balanced salt solution (BSS). During the first 7 d after injection, all the rabitts' eyes were examined by slit lamp, ophthalmoscope, intraocular pressure (IOP) and dark-adapted retina Electroretinography (ERG) each day. After that, the examination of IOG and ERP were reviewed weekly. Besides, B ultrasound should be examined to observe the situation of posterior vitreous detachment (PVD) in the 4th and 8th weeks. The rabbits were killed in the end of the 8th week, with their specimens examined by the light microscope, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Except group A, all the experimental eyes were produced with vitreous liquefaction. In group C and group D, in addition to the produced vitreous liquefaction, posterior vitreous detachment (PVD), even complete PVD, were induced in different extent. But in group B, the vitreous body was returned to the gel state at 2 weeks after gas absorption. In group C and group D, the vitreous body was not found to recover its original state at 8 weeks. In group D, there was a little increase of intraocular pressure, a mild delay of wave a and wave b after ERG in the 4th day after the gas injection. While there was no such situation in other groups. After the examination of B ultrasound in the 8th week, the complete PVD occurred in group C (with 2 experimental eyes occurred) and group D (with 4 experimental eyes occurred). Light microscope and transmission electron microscope examination showed no obvious abnormality. Smooth inner limiting membrane could be seen in the eye with PVD occurred when scanning electron microscope used. The injection of C3F8 into rabbit eyes can improve the vitreous liquefaction of the vitreous body and a certain volume of C3F8 can successfully and safely induce the PVD, and a larger volume of C3F8 was also effective but with a transient high IOP in rabbit eyes.