Cataracts, the most prevalent cause of blindness in humans, could one day be treated without surgery, eye drops tested on dogs suggests. A clouding of the lens in the eye leading to a decrease in vision, cataracts are most commonly due to aging, but may also occur due to trauma, radiation exposure, be present from birth, or occur following eye surgery for other problems.
The only treatment currently existing for cataracts is removal by surgery of the clouded lenses. The surgery is usually simple and safe, but the number of people who need it is predicted to double in the next 20 years as populations age. And for many, it is still prohibitively costly.
In the new study, a naturally-occurring molecule known as lanosterol, given with an eye dropper, shrank canine cataracts, a team of scientists reported.
Cataracts are frequently due to bunching of the proteins that comprise the lens. To further understanding of how eyes normally prevent this clumping and maintain lens transparency, scientists looked at the genes of two related families that both had a congenital, or inherited, form of the condition.
Lead researcher Kang Zhang of Sun Yat-sen University and colleagues found that these patients shared a mutation in a gene critical for producing lanosterol, which the researchers believed might impede cataract-forming proteins from clumping in normal eyes.
“The most important implication is that we can treat cataracts with an eyedrop, not surgery,” Zhang said, speaking to Live Science.
The first set of lab experiments on cells confirmed their suspicion that lanosterol helped stave off the proteins. Subsequent tests gave dogs with naturally-occurring cataracts eye drops containing the molecule.
Following six weeks of treatment, the size and characteristic cloudiness of the cataracts had decreased, the researchers reported.
“Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment,” the authors concluded.
The findings are very preliminary, J. Fielding Hejtmancik, a scientist at the US National Eye Institute, said in a commentary published in Nature. But, “The finding may lead to non-surgical prevention and treatment of cataracts”.
Ling Zhao, Xiang-Jun Chen, Jie Zhu, Yi-Bo Xi, Xu Yang, Li-Dan Hu, Hong Ouyang, Sherrina H. Patel, Xin Jin, Danni Lin, Frances Wu, Ken Flagg, Huimin Cai, Gen Li, Guiqun Cao, Ying Lin, Daniel Chen, Cindy Wen, Christopher Chung, Yandong Wang, Austin Qiu, Emily Yeh, Wenqiu Wang, Xun Hu, Seanna Grob, Ruben Abagyan, Zhiguang Su, Harry Christianto Tjondro, Xi-Juan Zhao, Hongrong Luo, Rui Hou, J. Jefferson, P. Perry, Weiwei Gao, Igor Kozak, David Granet, Yingrui Li, Xiaodong Sun, Jun Wang, Liangfang Zhang, Yizhi Liu, Yong-Bin Yan & Kang Zhang Lanosterol reverses protein aggregation in cataracts Nature (2015) doi:10.1038/nature14650
Illustration: Paul Griggs, Wellcome Images