Obtaining lissamine green 1% solution for clinical use

Purpose: With new compounding pharmacy laws, the only economically feasible approach to using lissamine is through dyeimpregnated strips. This research aims to determine the concentration of lissamine that can be obtained using a single commercially available lissamine strip. With the optimal vital staining requiring 1% concentration of lissamine, we sought to obtain this concentration using supplies in an ordinary ophthalmology clinic. Methods: A standard curve was generated using compounded lissamine green 1% solution. Serial dilutions were made with 3 different diluents and measured using a spectrophotometer at a wavelength of 633 mm. Combinations of the number of strips, amount of solvent, and absorption time were performed to obtain a 1% solution. Cost analyses were performed to select the most economical method. Results: Single lissamine strips wetted with any of the diluents produced 0.17% ± 0.05% (95% confidence interval) lissamine solution, a 5-fold weaker concentration than the optimal for vital staining. Combinations of 4 strips in 200 μL (4 drops) for 1 minute and 2 strips in 200 μL for 5 minutes were found to reach concentrations of 1%. Cost analysis showed that the 2 strip/4 drops/5 minutes method costs $0.67 and the 4 strips/4 drops/1 minute method $1.27. Conclusions: Use of a single lissamine strip leads to suboptimal concentrations for vital staining. With only the addition of disposable microcentrifuge tubes to the clinical setting, ophthalmologists can make 1% solutions of lissamine. This solution is both more economical and in compliance with both state and national compounding laws.