Integrity of the blood-ocular barrier after intravitreal gas injection

The authors studied the effect of various intravitreal gases on the integrity of the blood-ocular barrier using a fluorophotometric technique. The gas (0.3 ml) was injected into the vitreous cavity of a pigment rabbit after paracentesis. Air and two long-acting gases, sulfur hexafluoride and perfluoropropane, were studied. The eyes that received only paracentesis served as controls. Fluorescein concentrations in the anterior chamber were determined by slit-lamp fluorophotometer 30 minutes following intravenous fluorescein administration. Fluorophotometry was repeated on days 1, 3, 7, and 14 after the gas injections. The eyes that received sulfur hexafluoride and perfluoropropane showed increased aqueous fluorescein concentrations in comparison with the control eyes and the air-injected eyes, although conventional slit-lamp biomicroscopic examination detected no anterior chamber inflammatory signs in these eyes. The aqueous fluorescein leakage decreased to the normal level after the intravitreal gas bubble was absorbed. These results suggest that intravitreal gas bubbles induce subclinical breakdown of the blood-aqueous barrier, which becomes re-established soon after the gas is absorbed.