In order to create a safe anterior chamber environment that protects the eye and maintains the intraocular space during cataract surgery, surgeons have been using ophthalmic viscoelastic devices (OVDs) for more than 20 years. For many of those years, they have had only one option: a cohesive ophthalmic viscoelastic containing sodium hyaluronate (NaHA).
While a cohesive OVD contains a high-viscosity material with intramolecular adhesion and entanglement that is suitable for creating and maintaining space during capsulorhexis and IOL insertion, it does not protect corneal endothelium well, which makes it unsuitable for phacoemulsification.
However, dispersive OVDs contain a low-viscosity solution that adheres easily to intraocular structures and instruments, which protects corneal endothelium during phacoemulsification, although, given that dispersive solutions are difficult to remove, they are not ideal for use at the end of surgery.
My colleague and I have conducted research comparing the safety and efficacy of two OVDs that combine dispersive and cohesive solutions in a single device. We found that OVDs that combine both categories, so that they can be used in sequence and at the appropriate phases of cataract surgery, can result in decreased complications, low adverse events, improved visibility and good space management, which all enhance safety.