Cataracts, a leading cause of blindness in humans, may one day be treatable with eye drops instead of surgery.
In the journal Nature, a study led by the University of California-San Diego (UCSD) shows how a solution containing a natural steroid that can be given via eye drops decreased cataracts in dogs.
The lenses in our eyes are made mostly of crystallin proteins that have two jobs to do – they allow us to change focus and they keep the lens clear. Nobody knows exactly how they do this.
Cataracts is a condition that develops when the delicate structure of the crystallin proteins is disrupted and they start to form clumps and make the lens cloudy.
The lens is also rich in a molecule called lanosterol that is an essential building block of many important steroids in the body. Lanosterol is synthesized by an enzyme called lanosterol synthase.
The researchers began to look into lanosterol because they found children with an inherited form of cataracts had the same gene mutation that blocked lanosterol synthase.
They had a hunch that perhaps in normal eyes, where lenses are enriched with lanosterol, it stops the cataract-forming proteins from clumping.
The researchers ran three sets of experiments, starting with lab cells and progressing to animals.
First, in human lens cells, the team found lanosterol decreased clumping in cataract-forming proteins. They then showed treatment with lanosterol reduced cataracts and increased lens transparency in rabbits.
- Cataracts account for 51% of world blindness
- Most cataracts develop later in life
- Risk factors include too much sun, diabetes, tobacco and alcohol.
And, finally, when they tested the lanosterol solution – both in injected and eye drop form – in live dogs with cataracts, it had the same effect in reducing protein clumping as in the human lens cells and the rabbits’ lenses: the cataracts reduced and lens transparency improved.
The researchers conclude:
“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.”
Should lanosterol in the form of eye drops prove to be an effective treatment for cataracts in humans, it could be a game changer.
Currently, the only way to treat cataracts is with surgery. But this is not an option that is available to everyone. According to the World Health Organization (WHO), in many countries there are barriers that prevent patients accessing surgery, and so cataract remains the leading cause of blindness.
The new study follows another recent success story reported by Medical News Today where, after receiving an implanted bionic eye, an 80-year-old man with age-related macular degeneration regained some visual function.