THE ABSORPTION OF MIXTURES OF AIR AND PERFLUOROPROPANE AFTER PARS-PLANA VITRECTOMY

The duration of mixtures of perfluoropropane and air (0% to 20% C3F8) were analyzed in 206 eyes following pars plana vitrectomy for a variety of vitreoretinal disorders using a noninvasive model for calculating the intraocular gas bubble volume. The accuracy of the noninvasive model was tested by comparing the estimated bubble volume with the actual volume withdrawn from 12 eyes with intraocular gas bubbles undergoing a subsequent vitrectomy. The method for estimating intraocular bubble volume had a mean difference between the actual and estimated bubble volume of 0.1 +/- 0.35 mL. The half-life of air (0% C3F8) was 1.3 +/- 0.1 days; 5% C3F8, 4.2 +/- 0.1 days; 10% C3F8, 6.5 +/- 0.2 days; 15% C3F8, 8.0 +/- 0.6 days; and 20% C3F8, 12.5 +/- 1.1 days. The difference between each half-life was statistically significant (P<.01). Linear regression analysis of the halt-lives of C3F8 mixtures of up to 20% C3F8 showed a linear increase in half-lives with increasing concentrations Of C3F8. The duration of intraocular gas tamponade can be controlled by selecting the appropriate concentration of air and C3F8.