Researchers from the University of California, San Diego, have developed a new drug that can be administered directly into the eye through an eye dropper to shrink and dissolve cataracts – the leading cause of blindness in humans.
While the effects are yet to be tested on humans, the team hopes to replicate the findings in clinical trials and offer an alternative to the only treatment that is currently available to cataract patients, which is painful and often prohibitively expensive surgery.
According to the result published in a journal Pubmed, It has been estimated that cataract accounted for 47.8 percent of the 37 million people who were blind in Nigeria. However, surveys conducted earlier also showed that the prevalence of cataract blindness among people aged 50 and above ranged between 2.1 and 3.8 percent in Northern Nigeria and 4.1 percent in the Niger Delta.
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. While cataracts cannot spread from one eye to the other, they can occur independently in both eyes.
Although scientists are not totally sure of what causes cataracts, but most cases are related to age, with the US National Eye Institute reporting that by the age of 80, more than half of all Americans either have a cataract, or have had cataract surgery.
While unpleasant, the surgical procedure to remove a cataract is very simple and safe, but many communities in developing countries and regional areas do not have access to the money or facilities to perform it, which means blindness is inevitable for the vast majority of patients.
According to the results published on the journal Nature, 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 occurred 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 tested their lanosterol-based eye drops in three types of experiments. They worked with human lens in the lab and saw a decrease in cataract size. They then tested the effects on rabbits.
According to Hanae Armitage at Science Mag, 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. Just like the human lens in the lab and the rabbits, the dogs responded positively to the drug, with severe cataracts shrinking away to nothing, or almost nothing.
A molecular biologist Jonathan King from the Massachusetts Institute of Technology (MIT) told Armitage that this is a really comprehensive and compelling paper and the strongest he has seen of its kind in a decade.
While not affiliated with this study, King has been involved in cataract research for the past 15 years. While on this he discovered the phenomena and then followed with all of the experiments that he should do.
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.