Purpose:
The softshell technique, with injection of a dispersive OVD close to the cornea, and a cohesive OVD beneath is a commonly used technique. A disadvantage is that the dispersive OVD may be captured in the anterior chamber (AC) angle and cause postoperative IOP spikes. An opposite injection order is suggested to reduce this and was the focus of this study. The purpose was to visualize and evaluate the distribution of the OVDs for two product combinations, the Healon OVD + Healon Endocoat OVD (Abbott Medical Optics Inc.) and DuoVisc (Provisc + Viscoat, Alcon Inc.).
Methods:
Cataract surgery was simulated ex vivo in pig eyes (10 eyes per product combination). AC distribution of fluorescein stained OVDs was evaluated before surgery, after injection of cohesive OVD, after dispersive OVD, and after phacoemulsification by Scheimpflug photography (Pentacam HR, Oculus).
Results:
The Scheimpflug images visualize the dual OVD distribution within the AC in a unique way. Capsulorrhexis and hydrodissection were done with only cohesive OVD in AC. Injection of dispersive OVD, at site of rhexis, resulted in filling the entire AC depth but leaving the cohesive OVD in the AC angles. Phacoemulsification resulted in variable degree of retention of OVDs for both product combinations. In some cases it was possible to keep the AC filled with dual OVDs. In most eyes the cohesive OVD was emulsified, while the remaining dispersive OVD stayed centrally during the entire phaco procedure. In half of the cases all or almost all OVD was gone when lens was completely removed. No significant difference was seen between the two product combinations.
Conclusions:
This study shows that an injection of the cohesive OVD (Healon OVD or Provisc OVD) first prevents the dispersive OVD to be captured in the AC angle. Training and optimization of phaco settings is recommended before this injection technique may be a good alternative to the soft shell technique.
Keywords: cataract • anterior chamber • intraocular pressure