Trypan blue stains capsule, not lens, histology shows

Because trypan blue selectively stains the anterior lens capsule and not the adjacent lens cortex, it can help surgeons distinguish the capsule while performing capsulorrhexis, a histology study confirmed.

To study the histological characteristics of trypan blue, A.J. Singh, MD, and colleagues at the Hull Royal Infirmary in England stained the lens capsules in a series of 10 cataract surgeries with the dye. After capsulorrhexis, samples were sent to the lab for analysis. All 10 capsules were cut by frozen section to preserve the trypan blue staining and analyzed histologically. They were also subjected to immunohistochemistry for collagen IV.

Frozen section analysis using light microscopy demonstrated accumulation of trypan blue dye in the basement membrane of the lens capsule. Staining was concentrated in the portion of the membrane adjacent to the lens epithelium, which could not be clearly identified on the frozen sections. A counterstain highlighted the epithelium, confirming that the layer stained with trypan blue was the basement membrane.

The study is published in Eye.