A study conducted by Cell Press examined how cholesterol deposits in white blood cells known as macrophages contributed to blindness in the elderly. The team of researchers also probed possible medications for the disorder including an eye drop form that may reduce side effects.

Age-related macular degeneration, AMD, is a disease of the eye that gradually attacks the central vision controlled by the macula. It is the leading cause of blindness in people over the age of 50 and the risk increases as someone gets older.

Prior studies have highlighted the buildup of macrophage cholesterol and the abnormal growth of blood vessels that eventually leads to blindness.

"Our increased understanding of cholesterol's role in the growth of ocular blood vessels helped us identify therapeutically modifiable pathways, opening up avenues for new treatments that may help us prevent blindness caused by macular degeneration," says senior study author Rajendra Apte of Washington University School of Medicine

Apte and his research team took macrophage samples from elderly mice and humans with AMD and scanned their biological makeup and condition. They found that the white blood cells had low levels of ABCA1, a protein used for transporting cholesterol out of the cells. Without the ability to move cholesterol out of the macrophages, blood vessels will develop in larger numbers until it eventually causes blindness.

The older mice with AMD were given two types of cholesterol regulators, Liver X Receptor and microRNAs-33. In an eye solution and injected, both compounds contributed to ABCA1 protein levels which in turn helped decrease cholesterol buildup in white blood cells.

"Abnormal blood vessel growth is a characteristic of not only AMD, but also diverse disease processes outside the eye, including cancers and atherosclerosis, which are both associated with significant morbidity and mortality," Apte says. "Our findings may have significant relevance in our understanding of the pathobiology of these conditions."

The entire study was published in the April 2 edition of the journal Cell Metabolism.