New classification of ophthalmic viscosurgical devices—2005
Accepted 12 January 2005.
Purpose
To revise the generally accepted classification of ophthalmic viscosurgical devices (OVDs) to include cohesion data and the new class of viscous dispersive OVDs.
Setting
York Finch Eye Associates, Toronto, Ontario, Canada, and Alcon Research Limited, Fort Worth, Texas, USA.
Methods
Pseudoplasticity and cohesion-dispersion (CDI) data of DisCoVisc (hyaluronic acid 1.6%–chondroitin sulfate 4%), a new viscous dispersive OVD, were determined and compared with existing OVDs. The existing classification of OVDs was unable to accommodate its properties, so the classification was modified to include a new class and other potential new classes which currently remain unoccupied.
Results
Current OVD classification, although based on the clinically significant rheologic parameters of zero-shear viscosity and cohesion, only uses zero-shear viscosity because of the high correlation of these 2 parameters in existing OVDs. The appearance of DisCoVisc forces modification of the existing scheme because it does not fit into a preexisting category. The new proposed broadened classification is changed from a 1-dimensional list into a 2-dimensional table and considers CDI independently from viscosity for all OVDs. Expansion of the classification of OVDs in this manner predicts further possible new innovative OVDs for surgical use.
Conclusion
The surgical behavior of OVDs can be predicted by their position in a classification of OVDs based upon zero-shear viscosity and cohesion.
From the York Finch Eye Associates (Archinoff), Humber River Regional Hospital, and the University of Toronto (Arshinoff), Toronto, Ontario, Canada, and Alcon Research Limited (Jafari), R&D Surgical Formulation Development, Fort Worth, Texas, USA
Reprint requests to Steve A. Arshinoff, MD, FRCSC, York Finch Eye Associates, 2115 Finch Avenue West #316, Toronto, Ontario, M3N 2V6, Canada.
Dr. Arshinoff has acted as a paid consultant to a number of OVD manufacturers, including all of those whose products are referred to herein. Dr. Jafari is a full-time employee of Alcon Laboratories Inc.
ABSTRACT