Abstract
Purpose :
With considerable variability in the preparation of intravitreal injections (IVT), there has been some concern that viscous anesthetic gel may prevent adequate sterilization of the ocular surface. On the other hand, povidone-iodine (PI) is the only agent shown to decrease bacterial colonization. With the increasing number of IVTs, optimization of its steps would be critical to minimize endophthalmitis rates. Hence, we developed a representative eye model to test our hypothesis that application of PI for a short duration or with an anesthetic gel layer increases the rate of bacterial transfer from the surface to the inside of the eye model.
Methods :
We developed an eye model using bulbed plastic transfer pipettes filled with 3 cc of sterile growth media. They were then dipped in cultures of log-phase Staphylococcus epidermidis to coat the surface simulating bacterial colonization of external ocular surface. 0.05cc of sterile media was then injected into the reservoirs using 33G needles under the different settings of pre-injection preparation including 5% PI only for 5 seconds, 30 seconds, and 1 minute and PI followed by anesthetic gel coating and anesthetic gel coating followed by PI groups. After injections, the media was incubated for 48 hrs at 37oC. For each condition 10 replicates were performed and the experiment was repeated 3 times. T-test was then used to assess for statistical significance.
Results :
Surface bacterial transfer rate was 80%, 10% and 30% in PI only group for 5 seconds, 30 seconds and 1 minute of application respectively. There was significant difference between 5 sec and 30 sec or 1 min of PI treatment (p<0.05). Surface bacterial transfer rate was as high as 80% in anesthetic gel coating prior to 30 second PI treatment group, however was as low as 10% in PI prior to anesthetic gel coating group (p<0.05).
Conclusions :
Our data showed that short-time application of PI and application of anesthetic gel prior to PI increase surface bacterial transfer. However, anesthetic gel after PI application did not lead to increase in bacterial transfer from surface to the interior of our eye model. Our study suggests that variable pre-injection preparation steps can affect sterilization of the external ocular colonization and increase the risk for post injection endophthalmitis. Further study is needed to standardize the pre-injection preparation to minimize the risk for endophthalmitis.
This is a 2020 ARVO Annual Meeting abstract.