Corneal endothelium protection provided by ophthalmic viscosurgical devices during phacoemulsification: experimental study in rabbit eyes.

PURPOSE: To compare the protection of the corneal endothelium provided by a cohesive and a dispersive ophthalmic viscosurgical device (OVD) against damage from torsional ultrasound and simulated lenticular debris during phacoemulsification. SETTING: University setting, Salt Lake City, Utah. DESIGN: Experimental study. METHODS: 15 New Zealand rabbits were included. After incision, each eye received cohesive or dispersive OVD (ProVisc or Viscoat). 10 1.0 mm beads were injected to simulate lenticular debris. The Intrepid Balanced tip (Centurion Ozil handpiece) was inserted into the anterior chamber, and 60% torsional ultrasound with 50 mL/min flow, 70 mm Hg intraocular pressure, and 600 mm Hg vacuum was applied (20 seconds). Cumulative dissipated energy (CDE) was noted. After euthanasia and enucleation, corneas were removed, stained with trypan blue/alizarin red, and photographed (5 ×400 magnification photos and 1 overview photograph from each cornea). ImageJ was used to evaluate cell damage and loss. RESULTS: CDE was 4.70 ± 0.26 and 4.64 ± 0.10 in the cohesive and dispersive OVD groups, respectively ( P = .8647). The analysis of the ×400 photographs showed that the percentage of intact cells was statistically higher in the dispersive OVD group ( P = .0002), whereas the percentages of damaged and lost cells were statistically higher in the cohesive OVD group ( P = .0002 and .0059, respectively). Overview photographs revealed the presence of residual OVD on the endothelium, especially in the dispersive group. CONCLUSIONS: In this experimental study using a rabbit model, the corneal endothelium protection provided by the dispersive OVD was superior to that provided by the cohesive OVD.

Effect of simulated lenticular debris on corneal endothelial cells: experimental study in rabbit eyes.

PURPOSE: To evaluate mechanical damage of simulated lenticular debris on corneal endothelial cells during phacoemulsification. SETTING: University setting, Salt Lake City, Utah. DESIGN: Experimental study. METHODS: 12 New Zealand rabbits underwent bilateral surgery. After incision, 10 1.0 mm beads were injected into the anterior chamber of test eyes to simulate lenticular debris. A balanced salt solution was injected into the contralateral eyes with the same injector. The Intrepid Balanced Tip of the Centurion Ozil handpiece was inserted into the anterior chamber, and 60% torsional ultrasound was applied for 20 seconds with 50 mL/min flow, 70 mm Hg intraocular pressure, and 600 mm Hg vacuum. Cumulative dissipated energy (CDE) was noted. After euthanasia and enucleation, the corneas were removed, stained with trypan blue/alizarin red, and photographed in a standardized manner (×400 photographs from 5 specific areas and 1 overview photograph from each corneal button). The ImageJ program was used to evaluate cell damage and loss in the photographs. RESULTS: CDE was 4.64 ± 0.19 for test eyes with beads and 4.66 ± 0.17 for control eyes without beads ( P = .58). The percentage of intact cells was statistically higher in the control group ( P = .0005), whereas the percentages of damaged and lost cells were statistically higher in the test group ( P = .0010 and .0005, respectively). This was observed in the analysis of the ×400 photographs and overview photographs. CONCLUSIONS: This study suggests that lenticular debris swirling around the anterior chamber may cause significant damage to the corneal endothelium, providing further insight on mechanisms of damage during phacoemulsification.