Enhancing DMEK Success by Identifying Optimal Levels of Trypan Blue Dye Application to Donor Corneal Tissue.

PURPOSE: The purpose of this study was to determine the correct concentration and duration of application of trypan blue dye to Descemet membrane endothelial keratoplasty (DMEK) donor corneal tissue before transplant to enhance visibility while minimizing damage to the tissue.

METHODS: Corneas were precut for DMEK using an 8-mm punch, and each was stained with either 0.06% or 0.15% trypan blue for a duration of 1, 3, or 5 minutes. After staining, each tissue was placed in balanced salt solution and observed to determine how quickly the stain faded from the tissue using a grading system. Each cornea then underwent slit-lamp evaluation, specular microscopy, and assessment of the level of stain retained.

RESULTS: Tissue processed with 0.06% trypan blue for 1 minute regressed to a level 1 stain at an average of 109 minutes; tissue stained for 3 and 5 minutes regressed to a level 2 to 3 stain by 110 minutes. Endothelial cell density (ECD) was not affected when compared with prestaining measurements. Tissue processed with 0.15% trypan blue for 1 and 3 minutes regressed only to a level 2 to 3 stain at an average of 130 minutes; there was no change in ECD when stained for 1 to 3 minutes. Tissue stained for 5 minutes with 0.15% trypan blue regressed to a level 3 to 4 stain by 130 minutes. However, ECD was decreased by 11% when compared with prestaining measurements (P = 0.058).

CONCLUSIONS: Staining of DMEK donor tissue with VisionBlue (0.06%) up to 5 minutes is effective (visibility of staining is maintained for a sufficient period) and safe (no adverse effect on ECD). The higher concentration of trypan blue (0.15%, MembraneBlue) may be suggested during the learning curve of the DMEK surgeon, as it allowed a higher level of stain without adverse effects but only if used for 1 to 3 minutes; a longer staining time of 5 minutes resulted in a decrease in ECD, which approached statistical significance. Further study is required on use of the higher concentration of VisionBlue. The recent use of the "S" stamp may further help surgeons orient the graft correctly, thus requiring less intense trypan blue staining.