Canadian researchers describe novel 'uveolymphatic pathway'

Lymphatic vessels exist in the human ciliary body, and this novel "uveolymphatic" system appears to be rich and complex, according to Neeru Gupta, MD, PhD.

Dr. Gupta, University of Toronto, Canada, presented research using immunostaining techniques and confocal laser microscopy to investigate the presence of a lymphatic circulatory system in the ciliary body. The studies were performed using human eye sections obtained from the Eye Bank of Canada.

The results showed lymphatic channels were present in the circular, radial, and longitudinal portions of the ciliary muscle, stroma, and ciliary processes as well as around blood vessels within the ciliary body. Comparisons between healthy eyes and eyes from similarly aged donors with primary open-angle glaucoma showed a reduction in lymphatics in the glaucomatous eyes.

"It is generally accepted that there are no lymphatics inside the eye, but their presence in the human ciliary body has not been investigated," Dr. Gupta said. "Our identification of a uveolymphatic pathway is entirely in keeping with the well-known functions of the lymphatic system, which include drainage of extracellular fluid, removal of solutes, and immune surveillance.

"Now, further research is needed to understand the physiologic significance of this anatomic finding in normal eyes, to determine how its alteration might contribute to elevated IOP in glaucoma, and to investigate whether the lymphatic vessels of the ciliary body are a novel target for existing and new glaucoma therapies," Dr. Gupta said.