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AM Serrato, RT Tzekov, MF Marmor; The Lens-coating Agent and the Electroretinogram . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1174.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the composition and properties of commercial coating agents relative to effects on the ERG. Methods: Fifteen healthy volunteers (mean age 24 + 6 years) underwent photopic cone ERG recordings using Burian-Allen electrodes. The electrodes were repeatedly removed, cleaned and re-inserted using 0.5%, 1.0% or 2.5% methylcellulose (Isoptotears, Celluvisc, Gonak) solutions. Other components of those solutions were documented, and the conductivity of the solutions was measured. Results: Cone b wave amplitudes were roughly 15% lower with 1% solution relative to 0.5% solution. However, comparison between 1.0% and 2.5% solutions showed no significant changes in ERG amplitude. Conductivity was the same for 0.5% and 1.0% solutions, but about 50% lower for the 2.5% solution. Conclusion:Although higher ERG values were observed with 0.5% methylcellulose solution (currently recommended in the ISCEV standard), in comparison to 1% and 2.5% solution, the exact mechanism by which this occurs is unclear and may be a combination of factors such as conductivity, viscosity, or proprietary components. Higher methylcellulose concentrations may have advantages for comfort and stability, and be acceptable as long as a laboratory establishes normative values and consistently uses the same solution. The effects of coating agents on ERG amplitude cannot be predicted arbitrarily on the basis of methylcellulose concentration.
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