Lymphatic circulatory system could hold key to new target pathway for treating glaucoma

WASHINGTON — The discovery of a complex "uveolymphatic" pathway in the human ciliary body could assist in lowering IOP by introducing a novel target for treating the disease, according to a specialist speaking here.

Neeru Gupta, MD, and colleagues have been studying the human ciliary body to determine the presence of a lymphatic circulatory system and any abnormalities in that system in glaucoma patients. Dr. Gupta presented results of their research at the American Glaucoma Society meeting.

Investigators looked at systems in four normal human eye sections, which ranged in age from 57 years to 81 years. They compared these specimens with those of six eyes with primary open-angle glaucoma, which ranged in age from 63 years to 81 years.

The eye sections were triple-immunostained with D2-40, CD34 and SMA antibodies to study the lymphatic vessels, blood vessels and smooth muscle actin, respectively, Dr. Gupta said. Confocal laser microscopy was used to image the ciliary body.

Dr. Gupta and colleagues found that lymphatic vessels exist in the human ciliary body. In nonglaucomatous eyes, many D2-40 lymphatic channels were discovered in different parts of the ciliary muscle, stroma and ciliary process, she said. She described the uveolymphatic system in healthy eyes as a "dense, complex, interwoven system."

However, in glaucomatous eyes, the lymphatic channel network did not appear as structured. Dr. Gupta and colleagues suggested that the lymphatic system could play a part in aqueous humor regulation, influencing IOP levels.

"Glaucoma eyes may have reduced lymphatics. This is entirely in keeping with the well-known functions of the lymphatics," Dr. Gupta said. "It's possible that it's responsible for protein clearance from ciliary body interstition, the draining of fluid from the ciliary body and ciliary hydrodynamic involvement, and this may affect both aqueous formation and drainage."