The Slower the Better - On the Instability of Capillary Jets in a Model of Pneumatic Retinopexy

Abstract

Purpose:: To investigate the effect of injection technique parameters on the formation of multiple gas bubbles in a porcine eye model for pneumatic retinopexy.

Methods:: Three hundred and twenty four adult pig eyes were injected with 0.4ml of C₃F₈ with variations in the depth of injection, speed of injection, and size of the needle bore. The number of gas bubbles in the eye was assessed with indirect ophthalmoscopy.

Results:: Shallow injections resulted in a higher incidence of a single bubble compared to deep injections (p<0.001, Fisher exact and Wilcoxon rank-sum tests). Slow injections were significantly advantageous in producing a single gas bubble during shallow as well as during deep injections (p<0.001, Fischer exact and Wilcoxon rank-sum tests). In shallow needle insertion, slow speed of injection produced a single bubble in 75.9% of the eyes while moderately brisk injections resulted in one bubble in 50.9% of the eyes. During deep needle insertion, 44.4% of the eyes had one bubble if the gas was injected slowly and only 11.1% had a single bubble with moderately brisk gas injections. The bore of the needle did not significantly change the number of bubbles during deep or shallow injections.

Conclusions:: The factors that we found to be important in reducing the formation of multiple gas bubbles in the eye were shallow depth of injection and slow speed of gas delivery.

Keywords: retinal detachment • retina • vitreous