A study by researchers at the University of Kentucky and others, published in the journal Nature, found an enzyme known as DICER1 stops functioning, leading to the onset of the condition, the BBC reported Monday.
The disease affects the macula, a part of the eye at the center of the retina responsible for resolving fine detail at the center of the field of vision.
As the disease progresses the central vision deteriorates, making reading, driving and recognizing faces difficult.
The researchers found the DICER1 enzyme was less active in the retina of people with the more common "dry form" of the disease.
DICER1 is necessary for destroying small pieces of genetic material called Alu RNA which can accumulate with toxic affect leading to the deterioration of the retina, the researchers said.
"This work opens many new doors of research," lead researcher Professor Jayakrishna Ambati, from the University of Kentucky, said.
The exact cause of AMD unknown, but risk factors include smoking, high blood pressure and having relatives diagnosed with the condition.
"This is a very interesting piece of research and provides us with another valuable piece of the AMD jigsaw," Cathy Yelf, spokesperson for the Macular Disease Society, said.
"It will not change a thing for patients immediately but it may lead to new treatments in the long term."