Abstract
Purpose: :
In modern cataract surgery, the preferred technique includes phacoemulsification in combination with the injection of an ophthalmic viscosurgical device (OVD). The OVD maintains the anterior chamber depth, protects the corneal endothelium, and facilitates implantation of the IOL. The clinical impression is that dispersive OVDs retain in the anterior chamber and consequently better protect the corneal endothelium during phacoemulsification than OVDs with other physico-chemical characteristics. The purpose with this study was to objectively evaluate and visualize the effectiveness in OVD retention and maintenance of anterior chamber depth (ACD) by Scheimpflug photography for dispersive and viscoadaptive OVDs during different phacoemulsification settings (flow and vacuum).
Methods: :
Cataract surgery was simulated ex vivo in fresh porcine eyes. Dispersive (Viscoat and Vitrax II brand) and viscoadaptive (Healon5 brand) OVDs were stained with fluorescein, 6 µg/ml, for detection purposes. Each step in the surgeries was monitored by Scheimpflug photographs using the Pentacam HR (Oculus). ACD was measured before surgery, after injection of OVD, and after phacoemulsification (Sovereign Compact system, AMO) and presented as relative ACD of each eye compared to ACD before surgery. OVD retention is presented as OVD layer thickness after phacoemulsification relative to the ACD of each eye. Three different phacoemulsification flow and vacuum settings were used (low, medium, and high). Results were grouped according to product used at each step of the surgical procedure. The non-parametric Kruskal-Wallis test was used to evaluate differences between the medians of relative ACDs and retention of the products at each step in the surgeries.
Results: :
Contrary to the clinical impression that only dispersive products are retained in the anterior chamber during phacoemulsification the Pentacam Scheimpflug photographs allow us to objectively demonstrate that the viscoadaptive Healon5 OVD is retained in the anterior chamber during phacoemulsification at all settings tested. Healon5 OVD is retained to an equal or greater extent than the dispersive Viscoat and Vitrax II OVDs.
Conclusions: :
The viscoadaptive Healon5 OVD has the same retention capacity in the anterior chamber during phacoemulsification as the dispersive OVDs tested over a wide range of clinically relevant flow and vacuum settings.
Keywords: cataract • anterior chamber • training/teaching cataract surgery