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Cataract may be Treatable with Eye Drops
Cataracts, a leading cause of blindness in humans, may one day be treatable
with eye drops instead of surgery.
The University of California-San Diego (UCSD) has shown, that a solution
containing a natural steroid can be given via eye drops to decrease
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. But as
we get older, these crystallin proteins start to come unglued and lose their
ability to function. Then they clump together and form a sheathlike obstruction
in the lens, causing the signature “steamy glass” vision that accompanies
cataracts.
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. 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."
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Scientists have been hunting for years for mutations in crystallin proteins
that might offer new insights and pave the way to an alternate therapy.
 Now, it looks like a team led by University of California (UC), San Diego,
molecular biologist Ling Zhao may have done just that. Her team came up with the
eye drop idea after finding that children with a genetically inherited form of
cataracts shared a mutation that stopped the production of lanosterol, an
important steroid in the body. The team tested a lanosterol-laden solution in
three separate experiments. First, they used human lens cells to test how
effectively lanosterol shrank lab models of cataracts. They saw a significant
decrease. Then, they progressed to rabbits suffering from cataracts. At the end
of the 6-day experiment, 11 of 13 rabbits had gone from having severe or
significant cataracts to mild cataracts or no cataracts at all. Finally, the
team moved on to dogs, using a group of seven, including black Labs, Queensland
Heelers, and Miniature Pinschers with naturally occurring cataracts. The dogs
responded just as the researchers hoped to the lanosterol solution, which was
given in the form of both eye injections and eye drops. The dogs’ lenses showed
the same type of dissolving pattern as the human and rabbit lens cells.
The improvement was remarkable—researchers could tell just by looking at the
dogs’ eyes that the cataracts had decreased. But the exact mechanism of how
lanosterol manages to disperse the mass of proteins remains unknown.
Let's hope we'll see it soon, among humans, one fine day.
Dated 31 July 2015
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