Purchase this article with an account.
S. T. Lee, R. D. Glickman, S. Chalfin; Optical Properties of Viscoelastics. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1071.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Viscoelastics are used extensively in intraocular surgery. Their optical properties are important for the ability to visualize, distinguish, and resolve intraocular structures. The rheological properties of various viscoelastics are well characterized, but their optical properties have not been documented. The purpose of this study is to develop a systematic method to compare the optical properties of various viscoelastics.
Six different viscoelastics (Amvisc Plus, DisCoVisc, Healon, Healon GV, ProVisc, Viscoat) were studied. The refractive index of each viscoelastic was determined using a refractometer (Spectronic Instruments, ABBE-3L). An anterior chamber analog was created using a 96-well, flat-bottom tissue culture plate (Corning, #3596) and a cover glass (Clay Adams, No. 2). The wells were filled with mixtures consisting of differing concentrations of viscoelastic and BSS. The plate was then placed underneath a Zeiss operating microscope. The highest magnification setting on the microscope was used (25X) and the visualization through the mixture in each well was determined using a standard resolution test slide with the 1951 USAF test pattern (Edmund Optics, NT38-257). Absorption at 410 and 570 nm was measured using a SpectraCount plate reader (Packard Instruments, AS10000).
Refractive indices varied between 1.3380 and 1.3455, T=23° C. All of the listed products absorbed minimally at the two wavelengths tested, although Viscoat had a greater absorption at 410 nm than the other viscoelastics. The ability to resolve the target was in the range of 91 to 161 cycles/mm, with Healon GV demonstrating the poorest visualization.
The results suggest that there are subtle variations in the optical properties of different viscoelastics, which may influence the ability to visualize intraocular structures during surgery. Optical clarity may also be affected by the homogeneity of the viscoeleastic mixture. This systematic approach may be useful in characterizing and evaluating proposed new viscoelastics.
This PDF is available to Subscribers Only