An alternative to the Wratten #12 filter when judging central fluorescein patterns

The effectiveness of using the Wratten #12 filter to enhance the fluorescein pattern when judging the central pooling of rigid gas permeable (RGP) contact lenses is well established. As a money saving option, students at Pacific University have been using a substitute filter produced by a lighting company at 1/100 of the cost. The use of this alternative filter to judge fluorescein patterns has been done without scientific support of its efficacy. To compare these two filters, a subject was fit with RGP contact lenses of various base curves. Observers were asked to judge the degree of central pooling in diopters by comparing their view to a photometric scale. The filters and lenses were changed in a random order in a double blind fashion. Although no statistical difference was found between the performance of these two filters, their correlation was lower than expected. We believe the theater filter is a useful inexpensive tool that will enhance the observed image when eva I ua ting fluorescence patterns