Correlation between subretinal tissue plasminogen activator and air injection rates with pressure in a retina mimicking model

By investigating the correlation between the injection rate and pressure of subretinal tissue plasminogen activator (tPA) and air using a standard Viscous Fluid Control (VFC) system with a 38-gauge cannula, we aimed to establish guidelines for stable injections. We fabricated a retina mimicking model (RMM) with 0.25% agarose solution and an aluminum plate, and substituted submacular hemorrhage (SMH) and tPA with blood-mimicking fluid (BMF) and balanced salt solution (BSS), respectively. The diameter of the pre-bleb mimicking SMH in RMM was 1.30 +/- 0.16 cm, increasing to 1.98 +/- 0.24 cm and 1.83 +/- 0.22 cm after bleb propagation with BSS and air, respectively. BSS injection rates were 2.86 +/- 0.04 mu l/sec, 6.74 +/- 0.48 mu l/sec and 8.55 +/- 0.16 mu l/sec at 8, 12, and 16 psi, respectively. Air injection rates were 37.98 +/- 3.11 mu l/sec, 79.01 +/- 5.13 mu l/sec and 156.06 +/- 13.72 mu l/sec at 2, 3 and 4 psi, respectively. By experimenting with different pressures in the RMM, we found 12 psi to be the minimum for proper BSS injection and 2 psi for air. These findings provide crucial parameters for safer surgery to prevent irreversible damage.