FACTORS AFFECTING ASPIRATION VOLUMES OF BACK-FLUSH NEEDLES AND INFUSION VOLUMES OF VITRECTOMY DEVICE.

PURPOSE: The stability of the eye is important during vitrectomy, which makes it important to balance the infusion rates (IRs) and the aspiration rates (ARs). The purpose of this study was to determine the effects of the IR from the vitrectomy device and the AR with back-flush needles.

METHODS

We compared the ARs of 25-gauge or 27-gauge back-flush needles manufactured by four companies. The AR of balanced salt solution (BSS), ethylene glycol mimicking subretinal fluid, and air was measured for each aspiration pressure. The IR of BSS and air was measured at different intraocular pressures.

RESULTS

The AR increased in proportion to the increase in the aspiration pressure, and it was positively correlated with the cross-sectional area of the soft tips and negatively with the total length of the soft tips. The IR of BSS and air increased in proportion to the increase in the intraocular pressures settings. The IR of BSS exceeded the AR of BSS and ethylene glycol for all parameters, but the IR of air could be less than the AR at some settings.

CONCLUSION

The results suggest that the aspiration of air may cause a collapse of the eye under some settings.