A preventative drug for one of the most common causes of blindness in older people could be a step closer, as a result of new research by scientists at Trinity College Dublin.

The research team has found that a molecule naturally occurring in our bodies can suppress the production of damaging blood cells in the eye that cause Age-Related Macular Degeneration.

A condition that affects 70,000 people in Ireland, AMD involves a loss of central vision that can lead to an inability to carry out common tasks such as driving, watching TV and reading.

There are two forms of AMD; dry and wet.

Dry makes up the vast majority of cases, but wet AMD is the cause of 90% of the blindness that follows the disease.

Wet AMD sees the blood vessels below the retina, or light sensor, in the eye begin to grow abnormally and leak, causing almost immediate blindness in the eye affected.

Currently treatment for wet AMD is only available for the later stages of the disease.

It consists of regular monthly injections into the eye of antibodies, which mop up a molecule called VEGF which causes the problem.

But the injections do not cure the problem, which continues indefinitely and can lead to resistance.

However, the scientists at TCD discovered in 2012 that a protein called IL-18, which occurs naturally in human immune systems, can inhibit the production of VEGF in the first place. 

Results of subsequent trials on mice are published in this week's edition of the high-profile international journal Science Translational Medicine.

They found it can effectively control blood vessel production and also boost the immune processes that spur healing of the retinal tissue, without causing toxicity.

They found the molecule works as effectively as the current treatment when given as a non-invasive intravenous injection, and say it could potentially one day be used as a guardian of eyesight in older people.

Early indications suggest patients may be able to go for extended lengths of time before having to receive another IL-18 injection, potentially making it an effective treatment for wet AMD.

The researchers have cautioned, however, that an approved and licensed treatment for AMD using the molecule is a long way off as clinical trials must first be undertaken in humans.

However, that process may be speeded up by the fact that the pharmaceutical company GSK has already tested IL-18 in humans as a treatment for cancer and other illnesses, and found it to be safe.

The study was supported by Enterprise Ireland, Science Foundation Ireland, US-based charity Brightfocus Foundation and drug company GlaxoSmithKline.