Staining Grid : The Place for Contact Lens Biocompatibility Research This link opens in a new window"The Staining Grid is a reference tool allowing the eye care practitioner to evaluate the level of biocompatibility of various contact lens and multipurpose solutions. It is presented as a grid with the solutions listed across the top and the lens materials listed down the first column. The percentages which appear in each cell represent the average percentage of the cornea which was stained when observed at 2 hours after lens insertion."