Obtaining Lissamine Green 1% Solution for Clinical Use.

PURPOSE

With new compounding pharmacy laws, the only economically feasible approach to using lissamine is through dye-impregnated 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 μm. 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.