Abstract
Purpose :
During vitreous surgery, the stability of the eye is important to control the volume of intraocular infusion and aspirating fluid. If not controlled, the eyeball can collapse. We investigated the infusion and aspiration rate when using a back-flush needle in a non-clinical setting.
Methods :
Four types of 25G or 27G back-flush needles manufactured by Alcon (A), DORC (D), VitreQ (V), and MedOne (M) were compared. The inner diameter and total length of the silicone soft tip of each needle were measured. The aspiration rate of balanced salt solution (BSS), ethylene glycol (EG) mimicking subretinal fluid, and air was measured at aspiration pressures of 200, 400, and 650mmHg with the Constellation Vision System. The infusion rate of BSS and air from the infusion cannula was measured at IOP set at 10, 30, and 50mmHg.
Results :
The aspiration rate of BSS at aspiration pressure of 400mmHg by 25G-instruments was A, 16.7ml/min; D, 12.8ml/min; V, 10.8ml/min; M, 9.7ml/min; and that by 27G-instruments was A, 15.6ml/min; D, 8.6ml/min; V, 6.3ml/min; M, 5.0ml/min. The aspiration rate of air at aspirating pressure of 400mmHg by 25G-instruments was A, 375.6ml/min; D, 268.8ml/min; V, 204.0ml/min; M, 166.8ml/min; and that by 27G-instruments was A, 373.2ml/min; D, 208.8ml/min; V, 151.2ml/min; M, 133.2ml/min. The aspiration rate generally increased in proportion to the increase in the aspiration pressure and was positively correlated with the inner diameter and cross-sectional area of the soft tips, and negatively with the total lengths. The aspiration rate of BSS was significantly higher than that of EG for all IOP settings. Both BSS and air infusion rates increased in proportion to higher IOP settings, with the 25G infusion rate significantly higher than that of the 27G. At an IOP of 30mmHg, the BSS infusion rate was 42.6ml/min for 25G and 24.3ml/min for 27G. The infusion rates of BSS exceeded than aspiration rate of EG for all parameters. At an IOP of 30mmHg, the air infusion rate was 340.8ml/min for 25G and 204.0ml/min for 27G, but it was lower than the aspiration rate depending on the setting.
Conclusions :
The aspiration rate of the back-flush needle was positively correlated with the inner diameter and cross-sectional area of the soft tip, and negatively correlated with the total length. The results suggest that aspiration of air under air infusion may cause a collapse of the eye due to insufficient infusion rate.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.