Researchers in the US have developed a new drug that can be delivered directly into the eye via a dropper to shrink down and dissolve cataracts – the leading cause of blindness in humans.
While the effects have yet to be tested on humans, the team from the University of California San Diego hopes to replicate the findings in clinical trials and offer an alternative to the only treatment that’s currently available to cataract patients – sometimes painful and often prohibitively expensive surgery.
Affecting tens of millions of people worldwide, cataracts cause the lens of the eye to become progressively cloudy, and when left untreated, can lead to total blindness. This occurs when the structure of the crystallin proteins that make up the lens in our eyes deteriorates, causing the damaged or disorganised proteins to clump and form a milky blue or brown layer.
An estimated 32.4 million people around the world today are blind, and 90 percent of them live in developing countries. More than half of these cases were caused by cataracts, which means having an eye drop as an alternative to surgery would make an incredible difference.
The new drug is based on a naturally-occurring steroid called lanosterol. The idea to test the effectiveness of lanosterol on cataracts came to the researchers when they became aware of two children in China who had inherited a congenital form of cataract, which had never affected their parents.
The researchers discovered that these siblings shared a mutation that stopped the production of lanosterol, which their parents lacked. So if the parents were producing lanosterol and didn’t get cataracts, but their children weren’t producing lanosterol and did get cataracts, the researchers proposed that the steroid might halt the defective crystallin proteins from clumping together and forming cataracts in the non-congenital form of the disease.
They worked with human lens in the lab and saw a decrease in cataract size. They then tested the effects on rabbits…after six days, all but two of their 13 patients had gone from having severe cataracts to mild cataracts or no cataracts at all. Finally, they tested the eye drops on dogs with naturally occurring cataracts…(T)he dogs responded positively…with severe cataracts shrinking away to nothing, or almost nothing.
The next step is for the researchers to figure out exactly how the lanosterol-based eye drops are eliciting this response from the cataract proteins, and to progress their research to human trials.