[Study of retinal damage in rabbit eyes induced by air infusion during vitrectomy].

OBJECTIVE

To investigate the histologic and physiologic changes in rabbit retina damaged by infusion air and to explore the mechanism of vision defects after vitreoretinal surgery.

METHODS

Twenty four pigmented rabbits were randomly divided into three groups of eight each, a standard three port vitrectomy followed by fluid-air exchange was performed in 16 eyes, humidified air was infused with an air pressure of 25 or 40 mm Hg and then the vitreous cavity was refilled with balanced salt solution. As a control, vitrectomy without fluid-air exchange was performed in the remaining eight eyes. Clinical examinations and electroretinography were performed before and after the operation. Six weeks after the operation, the rabbits were sacrificed, their eyes were enucleated and examined by light and electron microscopy.

RESULTS

One day postoperatively, the value of bA ratio of group A and group B decreased significantly. Six weeks later, the physiologic function of eyes in group A seemed to have a tendency to recover while that of group B not. With light microscopy, the retina opposite the infusion location in eyes of group B was disorganized, with loss of some layers of sensory retina, and the thickness of total retina and the outer layer of the retina was sharply reduced, the changes in the latter appeared more prominently. With electron microscopy, marked lesions were observed in the nerve fiber layer and photoreceptor cells in eyes of group B, the pathologic changes in group A were slighter than that of group B. In contrast, no morphologic change was present in the control eyes.

CONCLUSION

Irreversible changes were produced in rabbit retina by air infusion during vitrectomy. The damages are more serious in the eyes perfused with higher air pressure. Air infusion during vitrectomy may be one of the main factors producing vision defects.