University of Toronto logoGlaucoma is said to be a degenerative disease which is caused by the death of nerve cells at the back of the eye and in vision centers of the brain. It may be frequently linked with prominent pressure in the eye. Existing treatments for glaucoma apparently depend on eye drops or surgery to lower eye pressure either by decreasing fluid formation or by improving fluid drainage from the eye.

Pertaining to glaucoma, researchers from the University of Toronto, St. Michael’s Hospital and Sunnybrook Health Sciences Centre have found a formerly unknown form of circulation in the human eye which may supply vital new insights into the disease.

For over a century, it has been known that the eye lacks lymphatics, which is apparently a circulation in charge of draining fluid and waste out of tissues. The failure to clear that fluid from the eye is supposedly connected to glaucoma. This disease is considered to be one of the biggest causes of irreversible blindness. Approximately 66 million people are affected all over the world.

Professor Yeni Yücel, a pathologist-scientist in U of T’s Faculty of Medicine and St. Michael’s Hospital, and lead author of the study, commented, “We challenged this assumption about a lack of lymphatics and discovered specialized lymphatic channels in the human eye.”

Study co-author Dr. Neeru Gupta, director of the glaucoma unit and nerve protection pnit at St. Michael’s Hospital and professor of ophthalmology at U of T, mentioned, “Good vision depends on the stable flow of fluid into and out of the eye. Any disturbance of this delicate fluid balance can lead to high eye pressure and irreversible glaucoma damage.”

The lymphatic circulation, which is claimed to be different from blood circulation, may transmit a colorless fluid known as lymph. It has extra water, proteins and antigens through lymphatic vessels to lymph nodes and then to the blood stream. This circulation could be crucial for the drainage of the fluid from tissues, clearance of proteins and immune supervising of the tissue. Via molecular tools and three-dimensional reconstruction, the team of researchers apparently recognized a rich group of lymphatic channels in the ciliary body of the human eye. It was apparently verified by electron microscopy.

The finding of a lymphatic circulation in the eye may confront the notion that the eye is said to be an immune-privileged site due to the lack of lymphatics and could have key connotations in understanding eye inflammations and eye tumor spread, among other eye disorders.

Gupta remarked, “This ‘uveolymphatic’ circulation plays a role in the clearance of fluid from the eye, making it highly relevant to glaucoma. This discovery is exciting because it means we can focus on innovative treatment strategies for patients with glaucoma by specifically targeting this new circulation to lower eye pressure.”

As per the researchers, additional analysis may be aimed at understanding how to influence the lymphatic circulation in the eye in a better way.

Yücel, who also serves as director of the ophthalmic pathology laboratory in U of T’s Department of Ophthalmology and research scientist at the Keenan Research Center at Li Ka Shing Knowledge Institute, SMH, quoted, “It’s clear that if we want to develop new strategies to prevent blindness, we need to challenge existing beliefs, and hopefully open the door to new treatments for eye disease.”

It is said that about 80 million people worldwide may suffer from glaucoma by 2020. Even though the disease could affect anybody, those with prominent eye pressure, the elderly, blacks and people with a family member with glaucoma are said to be at highest risk. Other threat issues that could be linked with glaucoma may include diabetes, high blood pressure and near-sightedness.

This research appears in the current issue of Experimental Eye Research.