New Delhi: A compound extracted from turmeric, a common Indian spice, may be used in eye drops to treat early stages of glaucoma and prevent loss of vision, British researchers have reported.

Scientists at the Imperial College and the University College London have developed a method to deliver curcumin, the yellow ingredient of turmeric, directly into the back of the eye through eye drops, overcoming the barrier of curcumin's poor solubility.

They have found that curcumin-laced eye drops can reduce the loss of retinal cells, an early sign of glaucoma, in laboratory rats. Their findings were published on Monday in the research journal Scientific Reports.

Glaucoma, which results from the loss of retinal ganglion cells --- nerve cells near the retinal surface --- affects an estimated 60 million people worldwide and can lead to blindness in a tenth of patients.

"Curcumin is an exciting compound that has shown promise at detecting and treating (the) neuro-degeneration implicated in several eye and brain conditions, from glaucoma to Alzheimer's disease," Francesa Cordeiro, the study's lead author, said in a media release. "So being able to administer it easily in eye drops may help people."

Some studies had suggested that curcumin, administered orally, can protect retinal ganglion cells. But others suggested that oral administration of curcumin doesn't help because it has poor solubility and does not get into the bloodstream. The body quickly excretes the curcumin.

For a meaningful dose, people might need to take up to 24 tablets a day, which could cause gastrointestinal side-effects, these studies had suggested.

The British scientists packed curcumin into a tiny "nano-carrier," a molecule created from a substance called a surfactant and a stabiliser, both known to be safe for human use and already used in present-day eye drops. The nano-carrier delivers the curcumin only into the eyes.

Rats that received the curcumin-laced eye drops twice daily for three weeks showed significant reductions in the retinal ganglion cell losses compared with rats that had received a placebo (sham eye drops).

The scientists say the treatment was "well tolerated", and the rats showed no signs of eye irritation or inflammation.

Several independent studies in the past, including some by scientists in India, had similarly explored the prospects of delivering curcumin into the body through nano-carriers to treat cancers.