Staining properties of deepithelialized human amniotic membrane

Purpose: The surgical use of human amniotic membrane (HAM) can be challenging because of its transparency, thin structure, and adhesive quality. Staining of HAM has been proposed to facilitate intraoperative visualization. We evaluated the in vitro staining properties of deepithelialized HAM using 5 vital dyes. Methods: Deepithelialized HAM was stained with indocyanine green (1.0%, 0.5%, 0.1%), fluorescein sodium (1.0%, 0.25%, 0.1%), lissamine green (0.5%, 0.1%), rose bengal (1.0%, 0.1%), and trypan blue (0.5%, 0.1%). The staining of each dyed sample was evaluated using a X10 operating microscope by a single observer. Each membrane was then rinsed, resuspended (3 mL of balanced salt solution), and then reevaluated for staining at 30-minute intervals for a total of 4 hours. All remaining stained samples were then placed in 5 mL balanced salt solution and then reevaluated for staining at 24 hours. Results: All concentrations of the 5 dyes stained the membrane initially. After 120 minutes, fluorescein sodium 0.1% and lissamine green 0.5% and 0.1% no longer stained the membrane. Fluorescein sodium 0.5% no longer stained at 210 minutes, and fluorescein sodium 1.0% no longer stained at 24 hours. All concentrations of indocyanine green, rose bengal, and trypan blue stained positively at 24 hours. Conclusions: All 5 dyes stain deepithelialized HAM initially. Tested concentrations of fluorescein sodium and lissamine green may be superior to other tested dyes for intraoperative use because these dyes stain the membrane and then fade. Tested concentrations of rose bengal, trypan blue, and ICG may not be ideal for clinical use because they demonstrate persistent staining at 24 hours.