Effectiveness of silicone oil removal from rabbit eyes

Silicone oil (1000 and 12,500 cs) and fluorosilicone oil (1000 and 10,000 cs) were dyed red and injected into a gas-created space in the vitreous cavity of 51 rabbit eyes. Later the oils were removed from the vitreous cavity either by lavage with balanced salt solution (group 1, 27 eyes) or by injecting a sodium hyaluronate solution, followed by lavage with balanced salt solution (group 2, 24 eyes). The average amount of oil retained in the vitreous cavity in group 1 was 0.0675 ml, and occasionally a large amount of oil was found (more than 0.1 ml in 30% of eyes). The average amount of oil retained in group 2 was 0.0114 ml, and no eye retained more than 0.1 ml of oil. The difference between the two groups was statistically significant (p less than 0.02), but there was no significant difference in oil retention within either group between the different kinds of oils, or between different viscosities of oil. The data suggest that residual oil can persist in the vitreous cavity despite thorough lavage, and that removal of silicone oil with the use of a sodium hyaluronate solution significantly lowers the risk of a large amount of residual silicone oil that is occasionally seen with conventional removal methods.